Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException in Finding Max Element

Whenever I am trying to run this code, it gives me out of bound exception. Can anyone point me out what's wrong with it. 

package com.programs.interview;
import java.util.Scanner;

public class FindMaxNumInArray {

public static void main (String[] args) 
{ 
    Scanner scan = new Scanner (System.in); 
    System.out.print("Enter the size of the array: "); 
    int arraySize = scan.nextInt(); 
    int[] myArray = new int[arraySize]; 
    System.out.print("Enter the " + arraySize + " values of the array: "); 
    for (int i = 0; i < arraySize; i++)
        myArray[i] = scan.nextInt(); 
    for (int j = 0; j < arraySize; j++) 
        System.out.println(myArray[j]); 
    System.out.println("In the array entered, the larget value is "+ maximum(myArray,arraySize) + "."); 
} 

public static int maximum(int[] arr, int Arraylength){
    int tmp;
    if (Arraylength == 0)
        return arr[Arraylength];
    tmp = maximum(arr, Arraylength -1);
    if (arr[Arraylength] > tmp)
        return arr[Arraylength];
    return tmp;
  }
}

Output

Enter the size of the array: 5 Enter the 5 values of the array: 1 2 3 4 5 1 2 3 4 5 Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 5 at com.programs.interview.FindMaxNumInArray.maximum(FindMaxNumInArray.java:26) at com.programs.interview.FindMaxNumInArray.main(FindMaxNumInArray.java:17)

Jon Skeet
people
quotationmark

This is the problem:

if (arr[Arraylength] > tmp)

Valid array indexes go from 0 to length-1 inclusive. array[array.length] is always invalid, and on the initial call, ArrayLength is equal to arr.length.

It's not clear why you're using recursion at all, to be honest. An iterative solution would be much simpler - but you'll need to work out what you want to do if the array is empty.

EDIT: If you really want how I would write the recursive form, it would be something like this:

/** Returns the maximum value in the array. */
private static int maximum(int[] array) {
    if (array.length == 0) {
        // You need to decide what to do here... throw an exception,
        // return some constant, whatever.
    }
    // Okay, so the length will definitely be at least 1...
    return maximumRecursive(array, array.length);
}

/** Returns the maximum value in array in the range [0, upperBoundExclusive) */
private static int maximumRecursive(int[] array, int upperBoundExclusive) {
    // We know that upperBoundExclusive cannot be lower than 1, due to the
    // way that this is called. You could add a precondition if you really
    // wanted.
    if (upperBoundExclusive == 1) {
        return array[0];
    }
    int earlierMax = maximumRecursive(array, upperBoundExclusive - 1);
    int topValue = array[upperBoundExclusive - 1];
    return Math.max(topValue, earlierMax);

    // Or if you don't want to use Math.max
    // return earlierMax > topValue ? earlierMax : topValue;
}

people

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