CODEWITHSUNDEEP
java
Nisha Sakash
Nisha Sakash

Reputation: 1

Program to reverse a number in array

When I try the following code it gives right answer. But when I try to use a.length it throws ArrayIndexOutOfBoundsException. How to make my code to use a.length?

public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int[] a;

    int n = sc.nextInt();
    a = new int[n];

    for(int i = 0; i <= a.length; i++) {
        a[i] = sc.nextInt();
    }

    for(int i = a.length; i >= 0; i--) {
        System.out.println(a[i]);
    }
}

Upvotes: 0

Views: 85

Answers (5)

rewrihitesh
rewrihitesh

Reputation: 35

    for(int i=0; i<=a.length; i++)  // let say a.length=5; 
        {                          // by default all the element start from 
        a[i]=sc.nextInt();        //index zero in array 0 1 2 3 4
    }                            //so there is nothing like a[5]
                                // that's why you are getting arrayOutOfBound 
    for(int i=a.length; i>=0; i--)
    {
        System.out.println(a[i]);
    }

}

Upvotes: 0

Tilak Madichetti
Tilak Madichetti

Reputation: 4346

You can make use of String functions in JAVA . The StringBuffer class is like a dynamic string with awesome built in methods .

public static void main(String[] args) {

  Scanner sc = new Scanner(System.in);
  int n = sc.nextInt();

  String num = String.valueOf(n);
  StringBuffer b = new StringBuffer(num);
  StringBuffer revNum = b.reverse();
  String rev = revNum.toString();
  int reversedNumber = Integer.parseInt(rev);

  System.out.println(reversedNumber);

}

Upvotes: 0

Shiladittya Chakraborty
Shiladittya Chakraborty

Reputation: 4418

public static void main(String[] args) {
  Scanner sc=new Scanner(System.in);
  int[] a;


  int n=sc.nextInt();
  a=new int[n];

  for(int i=0; i<a.length; i++) // Remove = from for loop
    {
    a[i]=sc.nextInt();
  }

  for(int i = a.length - 1; i>0; i--) // Modify here 
  {
    System.out.println(a[i]);
  }

 } 
}

Or for reverse an array you can use directly as below :

Collections.reverse(Arrays.asList(array));

Upvotes: 0

Vivek Singh
Vivek Singh

Reputation: 2073

You can only iterate through a.length-1 since the index position start with 0. so in the above case do the below change and it would work as required

  for(int i=0; i<a.length; i++)
    {
    a[i]=sc.nextInt();
}

Upvotes: 0

Jos
Jos

Reputation: 2013

there is no element in a at the index a.length, because index range of a will be from 0 to (a.length - 1). Since there is no index, that will throw the Exception.

Upvotes: 5

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