How do you separate zeros from non-zeros in an integer array using Java?

To separate zeros from non-zeros in an integer array, and push them to the end, you need to rearrange it array by assigning all the nonzero elements to its positions, sequentially, starting from zero. Then, from last position of the array to its end populate it with zeros.

Example

Following Java program pushes all the zeros in an array to its end.

import java.util.Arrays;
import java.util.Scanner;
public class ZerosFromNonZeros {
   public static void main(String args[]){
      //Reading the array from the user
      Scanner sc = new Scanner(System.in);
      System.out.println("Enter the size of the array that is to be created: ");
      int size = sc.nextInt();
      int[] myArray = new int[size];
      System.out.println("Enter the elements of the array: ");
      for(int i=0; i<size; i++){
         myArray[i] = sc.nextInt();
      }
      System.out.println("The array created is: "+Arrays.toString(myArray));
      System.out.println("Resultant array: ");
      int pos = 0;
      for(int i=0; i<myArray.length; i++){
         if(myArray[i]!=0){
            myArray[pos]=myArray[i];
            pos++;
         }
      }
      while(pos<myArray.length) {
         myArray[pos] = 0;
         pos++;
      }
      System.out.println("The array created is: "+Arrays.toString(myArray));
   }
}

Output

Enter the size of the array that is to be created:
8
Enter the elements of the array:
14
0
56
0
12
47
0
0
The array created is: [14, 0, 56, 0, 12, 47, 0, 0]
Resultant array:
The array created is: [14, 56, 12, 47, 0, 0, 0, 0]

In the same way to place the zeros at the starting of the array, iterate the elements of the array backwards, arrange each non-zero element in the array sequentially starting from the last position. Finally, fill the remaining positions with zeros.

rearrange it array by assigning all the nonzero elements to its positions, sequentially, starting from zero. Then, from last position of the array to its end populate it with zeros.

Example

Following Java program pushes all the zeros in an array to the start.

import java.util.Arrays;
import java.util.Scanner;
public class ZerosFromNonZeros {
   public static void main(String args[]){
      //Reading the array from the user
      Scanner sc = new Scanner(System.in);
      System.out.println("Enter the size of the array that is to be created: ");
      int size = sc.nextInt();
      int[] myArray = new int[size];
      System.out.println("Enter the elements of the array: ");
      for(int i=0; i<size; i++){
         myArray[i] = sc.nextInt();
      }
      System.out.println("The array created is: "+Arrays.toString(myArray));
      System.out.println("Resultant array: ");
      int pos = myArray.length-1;
      for(int i = myArray.length-1; i>=0; i--){
         if(myArray[i]!=0){
            myArray[pos]=myArray[i];
            pos--;
         }
      }
      while(pos>=0) {
         myArray[pos] = 0;
         pos--;
      }
      System.out.println("The array created is: "+Arrays.toString(myArray));
   }
}

Output

Enter the size of the array that is to be created:
8
Enter the elements of the array:
14
0
56
0
12
47
0
0
The array created is: [14, 0, 56, 0, 12, 47, 0, 0]
Resultant array:
The array created is: [0, 0, 0, 0, 14, 56, 12, 47]

Krishna Kasyap

Published on 02-Aug-2019 17:39:27