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Java Array Exercises: Move all 0's to the end of an array

Java Array: Exercise-26 with Solution

Write a Java program to move all 0's to the end of an array. Maintain the relative order of the other (non-zero) array elements.

Pictorial Presentation:

Java Array Exercises: Move all 0's to the end of an array

Sample Solution:

Java Code:

import java.util.*;
 public class Exercise26 {
     public static void main(String[] args) throws Exception {
        int[] array_nums = {0,0,1,0,3,0,5,0,6};
         int i = 0;
		System.out.print("\nOriginal array: \n");
		for (int n : array_nums)
            System.out.print(n+"  ");
		
        for(int j = 0, l = array_nums.length; j < l;) {
            if(array_nums[j] == 0)
                j++;
            else {
                int temp = array_nums[i];
                array_nums[i] = array_nums[j];
                array_nums[j] = temp;
                i ++;
                j ++;
            }
        }
        while (i < array_nums.length)
            array_nums[i++] = 0;
		System.out.print("\nAfter moving 0's to the end of the array: \n");
        for (int n : array_nums)
            System.out.print(n+"  ");
			System.out.print("\n");
    }
}

Sample Output:

                                                                              
Original array:                                                        
0  0  1  0  3  0  5  0  6                                              
After moving 0's to the end of the array:                              
1  3  5  6  0  0  0  0  0 

Flowchart:

Flowchart: Java exercises: Move all 0's to the end of an array

Visualize Java code execution (Python Tutor):


Java Code Editor:

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Next: Write a Java program to find the number of even and odd integers in a given array of integers.

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Java: Tips of the Day

Array vs ArrayLists:

The main difference between these two is that an Array is of fixed size so once you have created an Array you cannot change it but the ArrayList is not of fixed size. You can create instances of ArrayLists without specifying its size. So if you create such instances of an ArrayList without specifying its size Java will create an instance of an ArrayList of default size.

Once an ArrayList is full it re-sizes itself. In fact, an ArrayList is internally supported by an array. So when an ArrayList is resized it will slow down its performance a bit as the contents of the old Array must be copied to a new Array.

At the same time, it's compulsory to specify the size of an Array directly or indirectly while creating it. And also Arrays can store both primitives and objects while ArrayLists only can store objects.

Ref: https://bit.ly/3o8L2KH