Java Program To Find Second Largest Element In An Array
In This tutorial, we will see a Java program to find the second largest element in an array.
Introduction
In the previous article, Java Program To Find Largest Element In An Array (3 Ways), we have seen a few programs to find the largest element in an array. Today, we will see a program to find the secondlargest element in an array.
Here we will take an array of integers arr
and please note that arr
is not a sorted array. ex. {2, 5, 9, 8, 11, 18, 13}
Java Program to find the second largest element in an array
1. Iterating over an array
We will iterate over an array using the for
loop to find the second largest element in an array.
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/**
* A Java program to find the secondlargest number in an array
* by iterating over an array using a for loop.
*
* @author coderolls.com
*/
public class SecondLargestElementInArray {
public static void main(String[] args) {
int[] arr = {2, 5, 9, 8, 11, 18, 13};
int secondLargest = getSecondLargest(arr);
System.out.println("The second largest element in "
+ "an array 'arr'is: "+ secondLargest);
}
private static int getSecondLargest(int[] arr) {
int n =arr.length;
int largest =arr[0];
int secondLargest = 1;
for(int i=0; i<n; i++) {
if(arr[i]>largest) {
//if you found the new largest,
//copy current largest to second largest and
//copy current element arr[i] to largest
secondLargest = largest;
largest = arr[i];
}else if(arr[i]!=largest) {
// if the current element arr[i] is not the largest and
// still larger than the current secondLargest
// then copy it to secondLargest
if(arr[i]>secondLargest) {
secondLargest = arr[i];
}
}
}
return secondLargest;
}
}
Output:
1
The second largest element in an array 'arr' is: 13
Explanation:

In the main method, we have taken a sample array
arr = {2, 5, 9, 8, 11, 18, 13};
and passed it as a parameter to thegetSecondLargest()
method to return the largest number in an arrayarr
. 
In the
getSecondLargest()
method we have stored the length of an arrayarr
into int variable n using thearr.length
method. To start the program we have assigned the number at index0
i.e.arr[0]
as the current largest number i.e.largest
. Also, we have assigned the value1
the current second largest numbersecondLargest
.If the array contains all the similar numbers, there will be no secondlargest number in an array. ex.
arr= {12,12,12,12}
So it will return 1 in that case. 
Using the
if
statement we are checking if the current number at indexi
i.e.arr[i]
is larger than the current largest number i.elargest
, we will assign the current largest number
largest
tosecondLargest
 store current number i.e.
arr[i]
aslargest
 assign the current largest number

Next, we will check if the current number
arr[i]
is not the current largest numberlargest
but is still larger than the current second largest number, we will store it to thesecondLargest
. 
Return
secondLargest
.
2. Using Arrays.sort()
As the array is not sorted, we can sort it using the Arrays.sort()
method in natural sorting order. So the second last element of an array will be the second largest element of an array.
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import java.util.Arrays;
/**
* A Java program to find the secondlargest number in an array
* using Arrays.sort() method.
*
* @author coderolls.com
*/
public class SecondLargestElementInArrayUsingArrays {
public static void main(String[] args) {
int[] arr = {2, 5, 9, 8, 11, 18, 13};
int secondLargest = getSecondLargest(arr);
System.out.println("The second largest element in"
+ "an array 'arr' is using Arrays.sort() :"+ secondLargest);
}
private static int getSecondLargest(int[] arr) {
Arrays.sort(arr);
// return second largest, so length2
return arr[arr.length2];
}
}
Output:
1
The second largest element in an array 'arr' is using Arrays.sort(): 13
Explanation:
 In the main method, we have taken a sample array
arr = {2, 5, 9, 8, 11, 18, 13};
and passed it as a parameter to thegetSecondLargest()
method to return the largest number in an arrayarr
.  In the
getSecondLargest()
method, we have sorted an arrayarr
in natural sorting order using theArrays.sort()
method.  Once we sort the array in natural sorting order, we will have the second largest number as the second last element of the array. We can get the second last number of an array as
arr[arr.length2]
to return it.
In this way ( 2. Using
Arrays.sort()
) even if all the numbers of an array are similar ex.arr= {12,12,12,12}
, i.e. when there is no second largest element, it will return that same number.
Conclusion
We can find the second largest element in an array in the following two ways,
 By iterating over an array using a for loop to compare the largest and second largest number.
 By sorting an array in a natural sorting order and returning the second last element. i.e.
arr[arr.length2]
The example Java programs used in the above article can be found at this GitHub repository, blogpostcodingexamples/javaprograms/secondlargestelementinanarray/.
Please write your thoughts in the comment section below.
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