Method to find second highest number in an array in java

Question

Getting output of 0 each time when im ment to get 3 looked over my code my not sure where i have gone wrong i can do it without using a method i know but just trying to practice java

public class App {
    
    public static int second(int a[],int n) {
        int[] arr = new int [n];
        int temp;
        for(int i=0;i<n;i++) {
            for(int j=i+1;j<n;j++) {
                if(arr[i] > arr[j]) {
                    temp = arr[i];
                    arr[i] = arr[j];
                    arr[j] = temp;
                }
            }
        }
        return arr[n-2];
    }

    public static void main(String[] args) {
        int[] arr = {1,3,2,5,3};
        int n = 5;
        int result = second(arr,n);
        System.out.println(result);
    }
}

Answer 1

You could change the array parameter name arr and remove the declaration or copy the values from a to arr.

public static int second(int arr[],int n) {
    int temp;
    for(int i=0;i<n;i++) {
        for(int j=i+1;j<n;j++) {
            if(arr[i] > arr[j]) {
                temp = arr[i];
                arr[i] = arr[j];
                arr[j] = temp;
            }
        }
    }
    return arr[n-2];
}

The reason you get zero is because the primitive int cannot be null. So, when you create the array of length 5, it starts out filled with zeroes.

Answer 2

Doing it by using streams:

public static int second(int a[]) {
    return Arrays.stream(a)
            .sorted()
            .skip(a.length - 2)
            .findFirst()
            .getAsInt();
}

I removed the second argument. It sorts your array and skips all the elements prior to the one you want, before picking the now first element.

Answer 3

public static int second(int[] arr) {
    int highest = arr[0];
    int second = 0;
    for (int i = 1; i < arr.length; i++) {
        int j = arr[i];
        if (j >= highest) {
            highest = j;
        } else if (j > second) {
            second = j;
        }
    }
    return second;
}

public static void main(String[] args) {
    int[] arr = {1, 3, 2, 5, 3};
    int result = second(arr);
    System.out.println(result);
}

Answer 4

Here is one way that doesn't require sorting.

int[] arr = { 10, 2, 3, 19, 2, 3, 5 };
System.out.println(second(arr));

prints

10

• set largest to the first value in the array
• set secondLargest to the smallest possible
• now iterate thru the array.
• if the current value is greater than largest:
  • replace secondLargest with Largest
  • replace largest with current value
• else check to see if current value is greater than secondLargest and assign if true.

public static int second(int arr[]) {
    int largest = arr[0];
    int secondLargest = Integer.MIN_VALUE;
    for (int i = 1; i < arr.length; i++) {
        if (arr[i] > largest) {
            secondLargest = largest;
            largest = arr[i];
        } else if (arr[i] > secondLargest) {
            secondLargest = arr[i];
        }
    }
    return secondLargest;
}

Answer 5

public static int second(int arr[],int n) {
    int temp;
    if(arr.length < 2) {
        return -1;
    }
    else {
    for(int i=0;i<n;i++) {
        for(int j=i+1;j<n;j++) {
            if(arr[i] > arr[j]) {
                temp = arr[i];
                arr[i] = arr[j];
                arr[j] = temp;
            }
        }
    }
    return arr[n-2];
}

Answer 6

public static void main(String[] args) {
    // TODO Auto-generated method stub
    int a[] = {23,14,56,77,66,67};
    int high = 0;
    int sec = 0;
    for(int i = 0 ; i <a.length; i++){
        if(high < a[i]){
            sec = high;
            high = a[i];
        }
        else if(sec < a[i]){
            sec = a[i];
        }
        
    }
    System.out.println("the first highest number is " + high);
    System.out.println("the second highest number is " + sec);
}

}

Answer 7

public static int sec(){
    int arr[] = {12,3,67,4,5,65};
    int high = 0;
    int low = 0;
    for(int i = 0 ; i < arr.length ; i ++){
        
        if(high < arr[i]){
            low = high;
            high = arr[i];
        }
        else if(low < arr[i]){
            low = arr[i];           
            }
    }
    return low;
}
public static void main(String[] args) {
    // TODO Auto-generated method stub

    sch obj = new sch();
    int a = obj.sec();
    
    System.out.println(a);
}

}

Answer 8

package com; public class FindSecondHighestNumberInArray {

public static void main(String[] args) {
    int []arrayOfIngeger = {-23,-989,-878,-2,-5,-3,-4,-123,-345,-98,-675,-98};
    int highestNumber = arrayOfIngeger[0];
    int secHighestNumber = 0;
    for(int i = 1; i < arrayOfIngeger.length; i++  ) {
        if(highestNumber < arrayOfIngeger[i]) {
            System.out.println(highestNumber < arrayOfIngeger[i]);              
            secHighestNumber = highestNumber; 
            highestNumber = arrayOfIngeger[i];  
        }else if(secHighestNumber < arrayOfIngeger[i]) {
            secHighestNumber = arrayOfIngeger[i];
        }
    }
    System.out.println("second Highest Number in Array   :  "+secHighestNumber);
}

}