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Work on #403, made example readable and moved methods into utility

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This commit is contained in:
Narendra Pathai 2016-08-22 18:43:29 +05:30
parent 76970633b8
commit 95cf9fe367
4 changed files with 172 additions and 76 deletions
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promise/etc/promise.png
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30
promise/etc/promise.ucls
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@ -25,7 +25,7 @@
<position height="-1" width="-1" x="524" y="313"/>
<display autosize="true" stereotype="true" package="true" initial-value="false" signature="true"
sort-features="false" accessors="true" visibility="true">
<attributes public="true" package="false" protected="true" private="true" static="true"/>
<attributes public="true" package="false" protected="true" private="false" static="true"/>
<operations public="true" package="false" protected="true" private="true" static="true"/>
</display>
</class>
@ -67,42 +67,38 @@
</interface>
<class id="8" language="java" name="com.iluwatar.promise.App" project="promise"
file="/promise/src/main/java/com/iluwatar/promise/App.java" binary="false" corner="BOTTOM_RIGHT">
<position height="-1" width="-1" x="992" y="206"/>
<position height="-1" width="-1" x="822" y="251"/>
<display autosize="true" stereotype="true" package="true" initial-value="false" signature="true"
sort-features="false" accessors="true" visibility="true">
<attributes public="true" package="true" protected="true" private="true" static="true"/>
<attributes public="true" package="true" protected="true" private="false" static="true"/>
<operations public="true" package="true" protected="true" private="false" static="true"/>
</display>
</class>
<generalization id="9">
<end type="SOURCE" refId="1"/>
<end type="TARGET" refId="3"/>
</generalization>
<realization id="10">
<realization id="9">
<end type="SOURCE" refId="3"/>
<end type="TARGET" refId="2"/>
</realization>
<dependency id="11">
<dependency id="10">
<end type="SOURCE" refId="1"/>
<end type="TARGET" refId="6"/>
</dependency>
<dependency id="11">
<end type="SOURCE" refId="1"/>
<end type="TARGET" refId="5"/>
</dependency>
<dependency id="12">
<end type="SOURCE" refId="8"/>
<end type="TARGET" refId="1"/>
</dependency>
<dependency id="13">
<end type="SOURCE" refId="8"/>
<end type="TARGET" refId="4"/>
</dependency>
<dependency id="14">
<end type="SOURCE" refId="1"/>
<end type="TARGET" refId="7"/>
</dependency>
<dependency id="15">
<generalization id="14">
<end type="SOURCE" refId="1"/>
<end type="TARGET" refId="5"/>
</dependency>
<dependency id="16">
<end type="TARGET" refId="3"/>
</generalization>
<dependency id="15">
<end type="SOURCE" refId="1"/>
<end type="TARGET" refId="4"/>
</dependency>

127
promise/src/main/java/com/iluwatar/promise/App.java
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@ -21,19 +21,10 @@
* THE SOFTWARE.
*/
package com.iluwatar.promise;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;
import java.net.URL;
import java.util.Map;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executor;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
@ -59,7 +50,12 @@ import java.util.concurrent.Executors;
*/
public class App {
private static final String URL = "https://raw.githubusercontent.com/iluwatar/java-design-patterns/Promise/promise/README.md";
private ExecutorService executor;
private CountDownLatch canStop = new CountDownLatch(2);
private App() {
executor = Executors.newFixedThreadPool(2);
}
/**
@ -69,67 +65,80 @@ public class App {
* @throws ExecutionException if an execution error occurs.
*/
public static void main(String[] args) throws InterruptedException, ExecutionException {
ExecutorService executor = Executors.newSingleThreadExecutor();
App app = new App();
try {
promiseUsage(executor);
app.run();
} finally {
executor.shutdownNow();
app.stop();
}
}
private static void promiseUsage(Executor executor)
throws InterruptedException, ExecutionException {
String urlString = "https://raw.githubusercontent.com/iluwatar/java-design-patterns/Promise/promise/README.md";
Promise<Integer> lineCountPromise = new Promise<String>().fulfillInAsync(() -> {
return downloadFile(urlString);
}, executor).then(fileLocation -> {
return countLines(fileLocation);
});
private void run() throws InterruptedException, ExecutionException {
promiseUsage();
}
private void promiseUsage() {
Promise<Map<Character, Integer>> charFrequencyPromise = new Promise<String>().fulfillInAsync(() -> {
return String.valueOf(downloadFile(urlString));
}, executor).then(fileLocation -> {
return characterFrequency(fileLocation);
});
countLines()
.then(
count -> {
System.out.println("Line count is: " + count);
taskCompleted();
}
);
lineCountPromise.get();
System.out.println("Line count is: " + lineCountPromise.get());
charFrequencyPromise.get();
System.out.println("Char frequency is: " + charFrequencyPromise.get());
lowestCharFrequency()
.then(
charFrequency -> {
System.out.println("Char with lowest frequency is: " + charFrequency);
taskCompleted();
}
);
}
private static Map<Character, Integer> characterFrequency(String fileLocation) {
// TODO Auto-generated method stub
return null;
private Promise<Character> lowestCharFrequency() {
return characterFrequency()
.then(
charFrequency -> {
return Utility.lowestFrequencyChar(charFrequency).orElse(null);
}
);
}
private static Integer countLines(String fileLocation) {
int lineCount = 0;
try (Reader reader = new FileReader(fileLocation);
BufferedReader bufferedReader = new BufferedReader(reader);) {
for (String line; (line = bufferedReader.readLine()) != null; ) {
lineCount++;
}
} catch (IOException ex) {
ex.printStackTrace();
}
return lineCount;
private Promise<Map<Character, Integer>> characterFrequency() {
return download(URL)
.then(
fileLocation -> {
return Utility.characterFrequency(fileLocation);
}
);
}
private static String downloadFile(String urlString) throws InterruptedException, IOException {
URL url = new URL(urlString);
File file = File.createTempFile("promise_pattern", null);
try (Reader reader = new InputStreamReader(url.openStream());
BufferedReader bufferedReader = new BufferedReader(reader);
FileWriter writer = new FileWriter(file)) {
for (String line; (line = bufferedReader.readLine()) != null; ) {
writer.write(line);
writer.write("\n");
}
} catch (IOException ex) {
ex.printStackTrace();
}
System.out.println("File downloaded at: " + file.getAbsolutePath());
return file.getAbsolutePath();
private Promise<Integer> countLines() {
return download(URL)
.then(
fileLocation -> {
return Utility.countLines(fileLocation);
}
);
}
private Promise<String> download(String urlString) {
Promise<String> downloadPromise = new Promise<String>()
.fulfillInAsync(
() -> {
return Utility.downloadFile(urlString);
}, executor);
return downloadPromise;
}
private void stop() throws InterruptedException {
canStop.await();
executor.shutdownNow();
}
private void taskCompleted() {
canStop.countDown();
}
}

91
promise/src/main/java/com/iluwatar/promise/Utility.java Normal file
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@ -0,0 +1,91 @@
package com.iluwatar.promise;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Optional;
import java.util.Map.Entry;
public class Utility {
public static Map<Character, Integer> characterFrequency(String fileLocation) {
Map<Character, Integer> characterToFrequency = new HashMap<>();
try (Reader reader = new FileReader(fileLocation);
BufferedReader bufferedReader = new BufferedReader(reader);) {
for (String line; (line = bufferedReader.readLine()) != null;) {
for (char c : line.toCharArray()) {
if (!characterToFrequency.containsKey(c)) {
characterToFrequency.put(c, 1);
} else {
characterToFrequency.put(c, characterToFrequency.get(c) + 1);
}
}
}
} catch (IOException ex) {
ex.printStackTrace();
}
return characterToFrequency;
}
public static Optional<Character> lowestFrequencyChar(Map<Character, Integer> charFrequency) {
Optional<Character> lowestFrequencyChar = Optional.empty();
if (charFrequency.isEmpty()) {
return lowestFrequencyChar;
}
Iterator<Entry<Character, Integer>> iterator = charFrequency.entrySet().iterator();
Entry<Character, Integer> entry = iterator.next();
int minFrequency = entry.getValue();
lowestFrequencyChar = Optional.of(entry.getKey());
while (iterator.hasNext()) {
entry = iterator.next();
if (entry.getValue() < minFrequency) {
minFrequency = entry.getValue();
lowestFrequencyChar = Optional.of(entry.getKey());
}
}
return lowestFrequencyChar;
}
public static Integer countLines(String fileLocation) {
int lineCount = 0;
try (Reader reader = new FileReader(fileLocation);
BufferedReader bufferedReader = new BufferedReader(reader);) {
while (bufferedReader.readLine() != null) {
lineCount++;
}
} catch (IOException ex) {
ex.printStackTrace();
}
return lineCount;
}
public static String downloadFile(String urlString) throws MalformedURLException, IOException {
System.out.println("Downloading contents from url: " + urlString);
URL url = new URL(urlString);
File file = File.createTempFile("promise_pattern", null);
try (Reader reader = new InputStreamReader(url.openStream());
BufferedReader bufferedReader = new BufferedReader(reader);
FileWriter writer = new FileWriter(file)) {
for (String line; (line = bufferedReader.readLine()) != null; ) {
writer.write(line);
writer.write("\n");
}
System.out.println("File downloaded at: " + file.getAbsolutePath());
return file.getAbsolutePath();
} catch (IOException ex) {
throw ex;
}
}
}