The Collection framework provides a List interface that allows us to maintain an ordered collection of objects. The List interface is implemented by ArrayList, LinkedList, Stack, and Vector. Many Java programs use ArrayList and LinkedList. Throughout this article, we will learn how to iterate through a list in Java.
You can use three methods to iterate a list in Java. These four methods include:
Using the Enhanced For Loop Method
Using the iterator method
ForeEach iterable
a) Using the Enhanced For Loop Method
This is a more compact version of the basic for loop that can be used to iterate through a list:
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import java.util.ArrayList; import java.util.List; public class Enhanced_for_loop { public static void main(String[] args) { List<Integer> figurez = new ArrayList<>(); figurez.add(100); figurez.add(200); figurez.add(300); figurez.add(400); for(int i: figurez) { System.out.print(i+ " "); } } } |
Output
100 200 300 400
Using Iterator Method
You can also use iterators to iterate over a list. Iterators are especially useful when you need to modify the list that is being iterated.
Example
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import java.util.ArrayList; import java.util.Iterator; import java.util.List; public class Iterate_List_using_Iterators { public static void main(String[] args) { List<Integer> numbari = new ArrayList<>(); numbari.add(100); numbari.add(200); numbari.add(300); Iterator<Integer> itr = numbari.iterator(); while(itr.hasNext()) { int i = itr.next(); System.out.print(i+ " "); if(i==3) { itr.remove(); }
} } } |
Output
100 200 300
ForEach iterable
As a consequence of the introduction of lambda functions in Java, the forEach function was added, which allows you to iterate over any collection.
The following code shows how the forEach method can be used to iterate over a list:
Example
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import java.util.ArrayList; import java.util.List; public class Iterate_List_using_ForeEach_iterable { public static void main(String[] args) { List<Integer> numbari = new ArrayList<>(); numbari.add(1); numbari.add(2); numbari.add(3); numbari.add(4); numbari.forEach(System.out::println); } } |
Output
1
2
3
4
Keywords: Iterate List , List Iterator
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