90 lines
2.7 KiB
Markdown
90 lines
2.7 KiB
Markdown
---
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title: For Each Loop
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---
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# For Each Loop
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Also called the enhanced `for` loop, it is an extremely useful and simple way to iterate over each item in a collection, array or any object that implements the `Iterable` interface.
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```java
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for (object : iterable)
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{
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// Statements
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}
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```
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The loop is read as, "for each element in the `iterable` (could be an array, collectable etc.)". The `object` type must match the element type of the `iterable`.
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```java
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int[] number_list = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
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for (int numbers : number_list)
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{
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System.out.print(numbers + " ");
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// Iterated 10 times, numbers 0,1,2...9
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}
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```
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Output:
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```
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0 1 2 3 4 5 6 7 8 9
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```
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:rocket:<a href='https://repl.it/CJYs/0' target='_blank' rel='nofollow'>Run Code</a>
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Comparing this with the traditional `for` loops :
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```java
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int[] number_list = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
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for(int i=0;i < number_list.length;i++)
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{
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System.out.print(number_list[i]+" ");
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// Iterated 10 times, numbers 0,1,2...9
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}
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```
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Output:
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```
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0 1 2 3 4 5 6 7 8 9
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```
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:rocket:<a href='https://repl.it/NJfG/0' target='_blank' rel='nofollow'>Run Code</a>
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Both the above pieces of code snippets do the same work , however , clearly, the for each loops offer advantages in making iteration through and accessing of elements of a collection(array,in our case) easier.
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With the enhanced for loops we no longer need to mention starting and ending points for the loop,thus reducing OutofBounds errors.
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The need for loop counters and manual indexing are removed, and readability of the code is improved.
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If we do want a loop counter for a for each loop, all we have to do is create a variable outside the loop and iterate within it.
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It is important to note that making changes to the iterating variable for enhanced for loops within the loop causes no changes to the original collection elements.
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Enhanced for loops can also be used with multidimensional arrays or other Java collections.
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An example of its usage with multidimenisonal arrays are shown below:
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```java
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int number_list_new[][]={ { 0, 1, 2},
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{ 3, 4, 5},
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{ 6, 7, 8} };
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// Because 2d arrays are implemented as "arrays of arrays",the first iteration variable iterates
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// through 3 such arrays(that is, the 3 rows of testarr[][])
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for(int i[] : number_list_new)
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{
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for(int j : i){
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System.out.print(j+" ");
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}
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}
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```
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Output:
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```
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0 1 2 3 4 5 6 7 8
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```
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:rocket: <a href='https://repl.it/NJhP/0' target='_blank' rel='nofollow'>Run Code</a>
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In the above code snippets, `number_list` is an array. If you don't know what this is, don't worry about it. An array is a container object that holds a fixed number of values of a single type, but more on this later.
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