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Java - Iterator Examples

Java 

Iterator is a way to visit each elements of an Iterable. All Java collections implement Iterable.
In this example we are using remove method to remove an element from the underlying collection given by last next() call. 

package com.logicbig.example;

import java.util.Iterator;
import java.util.List;
import java.util.Stack;

public class IteratorRemoveExample {
    public static void main (String[] args) {
        List<String> list = new Stack<>();
        list.add("a");

        for (Iterator<String> i = list.iterator(); i.hasNext(); ) {
            String next = i.next();
            System.out.println(next);
            i.remove();
        }
        System.out.println(list);
    }
}

Output

a
[]
Original Post




Using Java 5 enhanced for loop to iterate through the elements. 

package com.logicbig.example;

import java.util.Arrays;
import java.util.List;

public class IteratorForLoopExample {
    public static void main (String[] args) {
        List<String> list = Arrays.asList("Apple", "Banana", "Orange");
        for (String s : list) {
            System.out.println(s);
        }
    }
}

Output

Apple
Banana
Orange
Original Post




Using Java 8 Iterator#forEach method along with a lambda expression. 

package com.logicbig.example;

import java.util.Arrays;
import java.util.List;

public class IteratorForEachExample {
    public static void main (String[] args) {
        List<String> list = Arrays.asList("Apple", "Banana", "Orange");
        list.forEach(System.out::println);
    }
}

Output

Apple
Banana
Orange
Original Post




This example demonstrate how to use a for loop with Iterator#hasNext() and Iterator#next() methods. 

package com.logicbig.example;

import java.util.Arrays;
import java.util.Iterator;
import java.util.List;

public class IteratorExample {

    public static void main (String[] args) {
        List<String> list = Arrays.asList("Apple", "Banana", "Orange");
        for (Iterator<String> i = list.iterator(); i.hasNext(); )
            System.out.println(i.next());
    }
}

Output

Apple
Banana
Orange
Original Post

Using Java 8 Iterator#forEachRemaining() method to apply given consumer action for each remaining element. 

package com.logicbig.example;

import java.util.Arrays;
import java.util.Iterator;
import java.util.List;

public class IteratorForEachRemainingExample {

    public static void main (String[] args) {
        List<String> list = Arrays.asList("Apple", "Banana", "Orange");
        Iterator<String> i = list.iterator();
        i.next();
        i.forEachRemaining(System.out::println);
    }
}

Output

Banana
Orange
Original Post

See Also