Ways to iterate over a list in Java

Question

Being somewhat new to the Java language I\'m trying to familiarize myself with all the ways (or at least the non-pathological ones) that one might iterate through a list (or

Answer 1

Above you'll find all differents ways to iterate over a LIST.

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

public class test1 {

public static void main(String[] args) {
    //******* Exercise 1 : Write a Java program to create a new array list, add some colors (string) and print out the collection.
    List colors = new ArrayList();
    colors.add("Black");
    colors.add("Red");
    colors.add("Green");
    colors.add("Blue");
    System.out.println(colors);
    
    
    //******* Exercise 2 : Write a Java program to iterate through all elements in a array list. 
    System.out.println("//******* Exercise 2");
    List list2 = Arrays.asList(1, 2, 3, 4, 5, 6, 7);
    
    // iteration type 1 : using FOR loop
    System.out.println("// iteration type 1");
    for(Integer nb : list2) {
        System.out.print(nb + ", ");
    }
    System.out.println("\n");
    
    // iteration type 2 : using FOR loop
    System.out.println("// iteration type 2");
    for(int i=0; i < list2.size(); i++) {
        System.out.print(list2.get(i) + ", ");
    }System.out.println("\n");
    
    // iteration type 3  : using Do-While loop
    System.out.println("// iteration type 3");
    int index21 = 0;
    
    do {
        System.out.print(list2.get(index21) + ", ");
        index21++;
    }while(index21 {
         System.out.print(elt + ", ");
     });

    System.out.println("\n");
    
    
    // iteration type 6  : using  Iterator
    System.out.println("// iteration type 6");
    Iterator listIterator = list2.iterator();
    while(listIterator.hasNext()) {
        System.out.print( listIterator.next() + ", ");
    }
    
    System.out.println("\n");
    
    // iteration type 7  : using  Iterator (From the beginning)
    System.out.println("// iteration type 7");
    ListIterator listIterator21 = list2.listIterator(list2.size());
    while(listIterator21.hasPrevious()) {
        System.out.print( listIterator21.previous() + ", ");
    }

    System.out.println("\n");   
    
    // iteration type 8  : using  Iterator (From the End)
    System.out.println("// iteration type 8");
    ListIterator listIterator22 = list2.listIterator();
    while(listIterator22.hasNext()) {
        System.out.print( listIterator22.next() + ", ");
    }

    System.out.println("\n");   
}

}