Increment Negative and Decrement Positive Numbers by 1 in an Array in Java

In Java, Array is an object. It is a non-primitive data type which stores values of similar data type.

As per the problem statement we have to increment all negative numbers by 1 and decrement all positive numbers by 1.

Let’s explore the article to see how it can be done by using Java programming language.

To Show You Some Instances

Instance-1

Suppose the original array is {12, 21, -31, -14, 56, 16, 17, -18, 9}

After updating the array element are: -30 -17 -13 8 11 15 16 20 55 (sorted)

Instance-2

Suppose the original array is {19, 11, -21, 14, 6, -16, 17, -18, 8}

After updating the array element are: -30 -17 -13 8 11 15 16 20 55 (sorted)

Instance-3

Suppose the original array is {1, 5, -3, 4, -5, 16, 17, -12, -9}

After updating the array element are: -11 -8 -4 -2 0 3 4 15 16 (sorted)

Algorithm

• Step 1 − Declare and initialize an integer array.

• Step 2 − Sort array in ascending order

• Step 3 − Initialize for loop to print original array elements

• Step 4 − Initialize another for loop to print updated array elements by adding 1 to negative array element and subtracting 1 from positive array elements.

• Step 5 − Print the elements of the array.

Syntax

To get the length of an array (number of elements in that array), there is an inbuilt property of array i.e length.

Below refers to the syntax of it −

array.length

Where, ‘array’ refers to the array reference.

Multiple Approaches

We have provided the solution in different approaches.

• By Using Static Initialization of Array

• By Using User Defined Method

Let’s see the program along with its output one by one.

Approach-1: By Using Static Initialization of Array

Example

In this approach, array elements will be initialized in the program. Then as per the algorithm increment all negative numbers by 1 and decrement all positive numbers by 1.

import java.util.*;
public class Main {

   //main method
   public static void main(String[] args){
   
      //Declare and initialize the array elements
      int[] arr = { 1, 5, -3, 4, -5, 16, 17, -12, -9 };
      
      //sorting array in ascending order
      System.out.print("Original array after sorting them in ascending order: ");
      System.out.print("\n");
      
      //for each loop to print original array elements
      for (int e : arr)
         System.out.print(e + " ");
      System.out.print("\n");
      System.out.print("Array after incrementing negative and decrementing positive numbers by 1: ");
      System.out.print("\n");
      
      //for loop to print array updated elements
      for (int e : arr){
         if(e < 0){
            e = e + 1;
            System.out.print(e + " ");
         } else {
            e = e - 1;
            System.out.print(e + " ");
         }
      }
   }
}

Output

Original array after sorting them in ascending order: 
1 5 -3 4 -5 16 17 -12 -9 
Array after incrementing negative and decrementing positive numbers by 1: 
0 4 -2 3 -4 15 16 -11 -8

Approach-2: By Using User Defined Method

Example

In this approach, array elements will be initialized in the program. Then call a user defined method by passing the array as parameter and inside method as per the algorithm increment all negative numbers by 1 and decrement all positive numbers by 1.

import java.util.*;
public class Main{

   //main method
   public static void main(String[] args){
   
      //Declare and initialize the array elements
      int[] arr = { 19, 11, -21, 14, 6, -16, 17, -18, 8 };
      
      //calling user defined method
      func(arr);   
   }
   
   //user defined method
   public static void func(int arr[]){
   
      //sorting array in ascending order
      Arrays.sort(arr);
      System.out.print("Original array after sorting them in ascending order: ");
      System.out.print("\n");
      
      //for each loop to print original array elements
      for (int e : arr)
         System.out.print(e + " ");
      System.out.print("\n");
      System.out.print("Array after incrementing negative and decrementing positive numbers by 1: ");
      System.out.print("\n");
      
      //for loop to print array updated elements
      for (int e : arr){
         if(e < 0){
            e = e + 1;
            System.out.print(e + " ");
         } else {
            e = e - 1;
            System.out.print(e + " ");
         }
      }
   }
}

Output

Original array after sorting them in ascending order: 
-21 -18 -16 6 8 11 14 17 19 
Array after incrementing negative and decrementing positive numbers by 1: 
-20 -17 -15 5 7 10 13 16 18

In this article, we explored different approaches to increment all negative numbers by 1 and decrement all positive numbers by 1 in an array by using Java programming language.