Reformat business-delegate, callback, chain, command, composite, dao, decorator & dependency-injection patterns.
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@ -2,23 +2,25 @@ package com.iluwatar.business.delegate;
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/**
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*
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* The Business Delegate pattern adds an abstraction layer between the presentation and business tiers.
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* By using the pattern we gain loose coupling between the tiers. The Business Delegate encapsulates
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* knowledge about how to locate, connect to, and interact with the business objects that make up
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* the application.
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* The Business Delegate pattern adds an abstraction layer between the presentation and business
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* tiers. By using the pattern we gain loose coupling between the tiers. The Business Delegate
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* encapsulates knowledge about how to locate, connect to, and interact with the business objects
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* that make up the application.
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* <p>
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* Some of the services the Business Delegate uses are instantiated directly, and some can be retrieved
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* through service lookups. The Business Delegate itself may contain business logic too potentially tying
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* together multiple service calls, exception handling, retrying etc.
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* Some of the services the Business Delegate uses are instantiated directly, and some can be
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* retrieved through service lookups. The Business Delegate itself may contain business logic too
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* potentially tying together multiple service calls, exception handling, retrying etc.
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* <p>
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* In this example the client ({@link Client}) utilizes a business delegate ({@link BusinessDelegate}) to execute a task.
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* The Business Delegate then selects the appropriate service and makes the service call.
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* In this example the client ({@link Client}) utilizes a business delegate (
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* {@link BusinessDelegate}) to execute a task. The Business Delegate then selects the appropriate
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* service and makes the service call.
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*
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*/
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public class App {
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/**
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* Program entry point
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*
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* @param args command line args
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*/
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public static void main(String[] args) {
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@ -2,8 +2,9 @@ package com.iluwatar.callback;
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/**
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*
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* Callback pattern is more native for functional languages where functions are treated as first-class citizens.
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* Prior to Java 8 callbacks can be simulated using simple (alike command) interfaces.
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* Callback pattern is more native for functional languages where functions are treated as
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* first-class citizens. Prior to Java 8 callbacks can be simulated using simple (alike command)
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* interfaces.
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*
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*/
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public class App {
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@ -11,5 +11,4 @@ public class SimpleTask extends Task {
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public void execute() {
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System.out.println("Perform some important activity and after call the callback method.");
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}
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}
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@ -5,8 +5,8 @@ import org.junit.Test;
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import static org.junit.Assert.assertEquals;
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/**
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* Add a field as a counter. Every time the callback method is called increment this
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* field. Unit test checks that the field is being incremented.
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* Add a field as a counter. Every time the callback method is called increment this field. Unit
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* test checks that the field is being incremented.
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*
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* Could be done with mock objects as well where the call method call is verified.
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*/
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@ -2,30 +2,29 @@ package com.iluwatar.chain;
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/**
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*
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* The Chain of Responsibility pattern is a design pattern consisting of command
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* objects and a series of processing objects. Each processing object contains
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* logic that defines the types of command objects that it can handle; the rest are
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* passed to the next processing object in the chain. A mechanism also exists for
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* adding new processing objects to the end of this chain.
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* The Chain of Responsibility pattern is a design pattern consisting of command objects and a
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* series of processing objects. Each processing object contains logic that defines the types of
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* command objects that it can handle; the rest are passed to the next processing object in the
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* chain. A mechanism also exists for adding new processing objects to the end of this chain.
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* <p>
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* In this example we organize the request handlers ({@link RequestHandler}) into a
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* chain where each handler has a chance to act on the request on its turn. Here
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* the king ({@link OrcKing}) makes requests and the military orcs ({@link OrcCommander},
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* {@link OrcOfficer}, {@link OrcSoldier}) form the handler chain.
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* In this example we organize the request handlers ({@link RequestHandler}) into a chain where each
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* handler has a chance to act on the request on its turn. Here the king ({@link OrcKing}) makes
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* requests and the military orcs ({@link OrcCommander}, {@link OrcOfficer}, {@link OrcSoldier})
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* form the handler chain.
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*
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*/
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public class App {
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/**
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* Program entry point
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*
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* @param args command line args
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*/
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public static void main(String[] args) {
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OrcKing king = new OrcKing();
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king.makeRequest(new Request(RequestType.DEFEND_CASTLE, "defend castle"));
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king.makeRequest(new Request(RequestType.TORTURE_PRISONER,
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"torture prisoner"));
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king.makeRequest(new Request(RequestType.TORTURE_PRISONER, "torture prisoner"));
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king.makeRequest(new Request(RequestType.COLLECT_TAX, "collect tax"));
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}
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@ -2,21 +2,22 @@ package com.iluwatar.command;
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/**
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*
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* The Command pattern is a behavioral design pattern in which an object is used to encapsulate all information
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* needed to perform an action or trigger an event at a later time. This information includes the method name,
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* the object that owns the method and values for the method parameters.
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* The Command pattern is a behavioral design pattern in which an object is used to encapsulate all
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* information needed to perform an action or trigger an event at a later time. This information
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* includes the method name, the object that owns the method and values for the method parameters.
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* <p>
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* Four terms always associated with the command pattern are command, receiver, invoker and client. A command
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* object (spell) knows about the receiver (target) and invokes a method of the receiver. Values for parameters of
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* the receiver method are stored in the command. The receiver then does the work. An invoker object (wizard)
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* knows how to execute a command, and optionally does bookkeeping about the command execution. The invoker
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* does not know anything about a concrete command, it knows only about command interface. Both an invoker object
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* and several command objects are held by a client object (app). The client decides which commands to execute at
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* which points. To execute a command, it passes the command object to the invoker object.
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* Four terms always associated with the command pattern are command, receiver, invoker and client.
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* A command object (spell) knows about the receiver (target) and invokes a method of the receiver.
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* Values for parameters of the receiver method are stored in the command. The receiver then does
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* the work. An invoker object (wizard) knows how to execute a command, and optionally does
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* bookkeeping about the command execution. The invoker does not know anything about a concrete
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* command, it knows only about command interface. Both an invoker object and several command
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* objects are held by a client object (app). The client decides which commands to execute at which
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* points. To execute a command, it passes the command object to the invoker object.
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* <p>
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* In other words, in this example the wizard casts spells on the goblin. The wizard keeps track of the previous
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* spells cast, so it is easy to undo them. In addition, the wizard keeps track of the spells undone, so they
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* can be redone.
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* In other words, in this example the wizard casts spells on the goblin. The wizard keeps track of
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* the previous spells cast, so it is easy to undo them. In addition, the wizard keeps track of the
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* spells undone, so they can be redone.
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*
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*
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*/
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@ -24,6 +25,7 @@ public class App {
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/**
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* Program entry point
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*
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* @param args command line args
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*/
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public static void main(String[] args) {
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@ -31,8 +31,8 @@ public abstract class Target {
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public abstract String toString();
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public void printStatus() {
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System.out.println(String.format("%s, [size=%s] [visibility=%s]", this,
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getSize(), getVisibility()));
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System.out.println(String.format("%s, [size=%s] [visibility=%s]", this, getSize(),
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getVisibility()));
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System.out.println();
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}
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}
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@ -13,8 +13,7 @@ public class Wizard {
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private Deque<Command> undoStack = new LinkedList<>();
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private Deque<Command> redoStack = new LinkedList<>();
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public Wizard() {
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}
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public Wizard() {}
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public void castSpell(Command command, Target target) {
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System.out.println(this + " casts " + command + " at " + target);
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@ -1,20 +1,21 @@
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package com.iluwatar.composite;
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/**
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* The Composite pattern is a partitioning design pattern. The Composite pattern
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* describes that a group of objects is to be treated in the same way as a single
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* instance of an object. The intent of a composite is to "compose" objects into
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* tree structures to represent part-whole hierarchies. Implementing the Composite
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* pattern lets clients treat individual objects and compositions uniformly.
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* The Composite pattern is a partitioning design pattern. The Composite pattern describes that a
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* group of objects is to be treated in the same way as a single instance of an object. The intent
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* of a composite is to "compose" objects into tree structures to represent part-whole hierarchies.
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* Implementing the Composite pattern lets clients treat individual objects and compositions
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* uniformly.
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* <p>
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* In this example we have sentences composed of words composed of letters. All of
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* the objects can be treated through the same interface ({@link LetterComposite}).
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* In this example we have sentences composed of words composed of letters. All of the objects can
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* be treated through the same interface ({@link LetterComposite}).
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*
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*/
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public class App {
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/**
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* Program entry point
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*
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* @param args command line args
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*/
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public static void main(String[] args) {
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@ -22,5 +22,4 @@ public class Letter extends LetterComposite {
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protected void printThisAfter() {
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// nop
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}
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}
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@ -15,20 +15,19 @@ public class Messenger {
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List<Word> words = new ArrayList<Word>();
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words.add(new Word(Arrays.asList(new Letter('W'), new Letter('h'),
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new Letter('e'), new Letter('r'), new Letter('e'))));
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words.add(new Word(Arrays.asList(new Letter('t'), new Letter('h'),
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new Letter('e'), new Letter('r'), new Letter('e'))));
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words.add(new Word(Arrays.asList(new Letter('W'), new Letter('h'), new Letter('e'), new Letter(
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'r'), new Letter('e'))));
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words.add(new Word(Arrays.asList(new Letter('t'), new Letter('h'), new Letter('e'), new Letter(
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'r'), new Letter('e'))));
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words.add(new Word(Arrays.asList(new Letter('i'), new Letter('s'))));
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words.add(new Word(Arrays.asList(new Letter('a'))));
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words.add(new Word(Arrays.asList(new Letter('w'), new Letter('h'),
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new Letter('i'), new Letter('p'))));
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words.add(new Word(Arrays.asList(new Letter('t'), new Letter('h'),
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new Letter('e'), new Letter('r'), new Letter('e'))));
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words.add(new Word(Arrays.asList(new Letter('w'), new Letter('h'), new Letter('i'), new Letter(
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'p'))));
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words.add(new Word(Arrays.asList(new Letter('t'), new Letter('h'), new Letter('e'), new Letter(
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'r'), new Letter('e'))));
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words.add(new Word(Arrays.asList(new Letter('i'), new Letter('s'))));
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words.add(new Word(Arrays.asList(new Letter('a'))));
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words.add(new Word(Arrays.asList(new Letter('w'), new Letter('a'),
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new Letter('y'))));
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words.add(new Word(Arrays.asList(new Letter('w'), new Letter('a'), new Letter('y'))));
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return new Sentence(words);
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@ -38,18 +37,18 @@ public class Messenger {
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List<Word> words = new ArrayList<Word>();
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words.add(new Word(Arrays.asList(new Letter('M'), new Letter('u'),
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new Letter('c'), new Letter('h'))));
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words.add(new Word(Arrays.asList(new Letter('w'), new Letter('i'),
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new Letter('n'), new Letter('d'))));
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words.add(new Word(Arrays.asList(new Letter('p'), new Letter('o'),
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new Letter('u'), new Letter('r'), new Letter('s'))));
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words.add(new Word(Arrays.asList(new Letter('f'), new Letter('r'),
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new Letter('o'), new Letter('m'))));
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words.add(new Word(Arrays.asList(new Letter('y'), new Letter('o'),
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new Letter('u'), new Letter('r'))));
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words.add(new Word(Arrays.asList(new Letter('m'), new Letter('o'),
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new Letter('u'), new Letter('t'), new Letter('h'))));
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words.add(new Word(Arrays.asList(new Letter('M'), new Letter('u'), new Letter('c'), new Letter(
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'h'))));
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words.add(new Word(Arrays.asList(new Letter('w'), new Letter('i'), new Letter('n'), new Letter(
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'd'))));
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words.add(new Word(Arrays.asList(new Letter('p'), new Letter('o'), new Letter('u'), new Letter(
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'r'), new Letter('s'))));
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words.add(new Word(Arrays.asList(new Letter('f'), new Letter('r'), new Letter('o'), new Letter(
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'm'))));
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words.add(new Word(Arrays.asList(new Letter('y'), new Letter('o'), new Letter('u'), new Letter(
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'r'))));
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words.add(new Word(Arrays.asList(new Letter('m'), new Letter('o'), new Letter('u'), new Letter(
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't'), new Letter('h'))));
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return new Sentence(words);
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@ -24,5 +24,4 @@ public class Sentence extends LetterComposite {
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protected void printThisAfter() {
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System.out.print(".");
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}
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}
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@ -24,5 +24,4 @@ public class Word extends LetterComposite {
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protected void printThisAfter() {
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// nop
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}
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}
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@ -7,14 +7,16 @@ import org.apache.log4j.Logger;
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/**
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*
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* Data Access Object (DAO) is an object that provides an abstract interface to some type of database or other
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* persistence mechanism. By mapping application calls to the persistence layer, DAO provide some specific data
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* operations without exposing details of the database. This isolation supports the Single responsibility principle.
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* It separates what data accesses the application needs, in terms of domain-specific objects and data types
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* (the public interface of the DAO), from how these needs can be satisfied with a specific DBMS.
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* Data Access Object (DAO) is an object that provides an abstract interface to some type of
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* database or other persistence mechanism. By mapping application calls to the persistence layer,
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* DAO provide some specific data operations without exposing details of the database. This
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* isolation supports the Single responsibility principle. It separates what data accesses the
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* application needs, in terms of domain-specific objects and data types (the public interface of
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* the DAO), from how these needs can be satisfied with a specific DBMS.
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* <p>
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* With the DAO pattern, we can use various method calls to retrieve/add/delete/update data without directly
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* interacting with the data. The below example demonstrates basic CRUD operations: select, add, update, and delete.
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* With the DAO pattern, we can use various method calls to retrieve/add/delete/update data without
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* directly interacting with the data. The below example demonstrates basic CRUD operations: select,
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* add, update, and delete.
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*
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*/
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public class App {
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@ -2,21 +2,21 @@ package com.iluwatar.decorator;
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/**
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*
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* The Decorator pattern is a more flexible alternative to subclassing. The Decorator
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* class implements the same interface as the target and uses composition to
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* "decorate" calls to the target. Using the Decorator pattern it is possible to
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* change the behavior of the class during runtime.
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* The Decorator pattern is a more flexible alternative to subclassing. The Decorator class
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* implements the same interface as the target and uses composition to "decorate" calls to the
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* target. Using the Decorator pattern it is possible to change the behavior of the class during
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* runtime.
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* <p>
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* In this example we show how the simple {@link Troll} first attacks and then
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* flees the battle. Then we decorate the {@link Troll} with a {@link SmartTroll}
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* and perform the attack again. You can see how the behavior changes after the
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* decoration.
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* In this example we show how the simple {@link Troll} first attacks and then flees the battle.
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* Then we decorate the {@link Troll} with a {@link SmartTroll} and perform the attack again. You
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* can see how the behavior changes after the decoration.
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*
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*/
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public class App {
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/**
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* Program entry point
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*
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* @param args command line args
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*/
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public static void main(String[] args) {
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package com.iluwatar.decorator;
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/**
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* SmartTroll is a decorator for {@link Hostile} objects.
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* The calls to the {@link Hostile} interface are intercepted
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* and decorated. Finally the calls are delegated
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* to the decorated {@link Hostile} object.
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* SmartTroll is a decorator for {@link Hostile} objects. The calls to the {@link Hostile} interface
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* are intercepted and decorated. Finally the calls are delegated to the decorated {@link Hostile}
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* object.
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*
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*/
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public class SmartTroll implements Hostile {
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System.out.println("The troll calls for help!");
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decorated.fleeBattle();
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}
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}
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@ -19,5 +19,4 @@ public class Troll implements Hostile {
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public void fleeBattle() {
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System.out.println("The troll shrieks in horror and runs away!");
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}
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}
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@ -2,9 +2,8 @@ package com.iluwatar.dependency.injection;
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/**
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*
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* AdvancedWizard implements inversion of control.
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* It depends on abstraction that can be injected through
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* its constructor.
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* AdvancedWizard implements inversion of control. It depends on abstraction that can be injected
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* through its constructor.
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*
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*/
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public class AdvancedWizard implements Wizard {
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@ -10,24 +10,25 @@ import com.google.inject.Injector;
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* - High-level modules should not depend on low-level modules. Both should depend on abstractions.
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* - Abstractions should not depend on details. Details should depend on abstractions.
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* <p>
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* In this example we show you three different wizards. The first one ({@link SimpleWizard}) is a naive
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* implementation violating the inversion of control principle. It depends directly on a concrete
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* implementation which cannot be changed.
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* In this example we show you three different wizards. The first one ({@link SimpleWizard}) is a
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* naive implementation violating the inversion of control principle. It depends directly on a
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* concrete implementation which cannot be changed.
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* <p>
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* The second wizard ({@link AdvancedWizard}) is more flexible. It does not depend on any concrete implementation
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* but abstraction. It utilizes Dependency Injection pattern allowing its {@link Tobacco} dependency to be
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* injected through its constructor. This way, handling the dependency is no longer the wizard's
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* responsibility. It is resolved outside the wizard class.
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* The second wizard ({@link AdvancedWizard}) is more flexible. It does not depend on any concrete
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* implementation but abstraction. It utilizes Dependency Injection pattern allowing its
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* {@link Tobacco} dependency to be injected through its constructor. This way, handling the
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* dependency is no longer the wizard's responsibility. It is resolved outside the wizard class.
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* <p>
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* The third example takes the pattern a step further. It uses Guice framework for Dependency Injection.
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* {@link TobaccoModule} binds a concrete implementation to abstraction. Injector is then used to create
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* {@link GuiceWizard} object with correct dependencies.
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* The third example takes the pattern a step further. It uses Guice framework for Dependency
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* Injection. {@link TobaccoModule} binds a concrete implementation to abstraction. Injector is then
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* used to create {@link GuiceWizard} object with correct dependencies.
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*
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*/
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public class App {
|
||||
|
||||
/**
|
||||
* Program entry point
|
||||
*
|
||||
* @param args command line args
|
||||
*/
|
||||
public static void main(String[] args) {
|
||||
|
@ -4,9 +4,8 @@ import javax.inject.Inject;
|
||||
|
||||
/**
|
||||
*
|
||||
* GuiceWizard implements inversion of control.
|
||||
* Its dependencies are injected through its constructor
|
||||
* by Guice framework.
|
||||
* GuiceWizard implements inversion of control. Its dependencies are injected through its
|
||||
* constructor by Guice framework.
|
||||
*
|
||||
*/
|
||||
public class GuiceWizard implements Wizard {
|
||||
|
@ -2,8 +2,8 @@ package com.iluwatar.dependency.injection;
|
||||
|
||||
/**
|
||||
*
|
||||
* Naive Wizard implementation violating the inversion of control principle.
|
||||
* It should depend on abstraction instead.
|
||||
* Naive Wizard implementation violating the inversion of control principle. It should depend on
|
||||
* abstraction instead.
|
||||
*
|
||||
*/
|
||||
public class SimpleWizard implements Wizard {
|
||||
|
@ -8,6 +8,7 @@ package com.iluwatar.dependency.injection;
|
||||
public abstract class Tobacco {
|
||||
|
||||
public void smoke(Wizard wizard) {
|
||||
System.out.println(String.format("%s smoking %s", wizard.getClass().getSimpleName(), this.getClass().getSimpleName()));
|
||||
System.out.println(String.format("%s smoking %s", wizard.getClass().getSimpleName(), this
|
||||
.getClass().getSimpleName()));
|
||||
}
|
||||
}
|
||||
|
Loading…
x
Reference in New Issue
Block a user