Java Guava | Longs.lastIndexOf() method with Examples

The lastIndexOf() method of Longs Class in Guava library is used to find the last index of the given long value in a long array. This long value to be searched and the long array in which it is to be searched, both are passed as a parameter to this method. It returns an integer value which is the last index of the specified long value. If the value is not found, it returns -1.

Syntax:

public static int lastIndexOf(long[] array,
                              long target)

Parameters: This method accepts two mandatory parameters:

• array: which is the array of long values in which the long value is to searched.
• target: which is long value to be searched for last index in the long array.

Return Value: This method returns an integer value which is the last index of the specified long value. If the value is not found, it returns -1.

Below programs illustrates this method:

Example 1:

// Java code to show implementation of
// Guava's Longs.lastIndexOf() method

import com.google.common.primitives.Longs;
import java.util.Arrays;

class GFG {

    // Driver's code
    public static void main(String[] args)
    {

        // Creating a long array
        long[] arr = { 1, 2, 3, 4, 3, 5, 3, 4 };

        long target = 3;

        // Using Longs.lastIndexOf() method
        // to get the index of last appearance
        // of a given element in array
        // and return -1 if element is
        // not found in the array
        int index
            = Longs.lastIndexOf(arr, target);

        if (index != -1) {
            System.out.println("Target is present"
                               + " at index "
                               + index);
        }
        else {
            System.out.println("Target is not present"
                               + " in the array");
        }
    }
}

Output:

Target is present at index 6

Example 2:

// Java code to show implementation of
// Guava's Longs.lastIndexOf() method

import com.google.common.primitives.Longs;
import java.util.Arrays;

class GFG {

    // Driver's code
    public static void main(String[] args)
    {
        // Creating a long array
        long[] arr = { 3, 5, 7, 11, 13 };

        long target = 17;

        // Using Longs.lastIndexOf() method
        // to get the index of last appearance
        // of a given element in array
        // and return -1 if element is
        // not found in the array
        int index
            = Longs.lastIndexOf(arr, target);

        if (index != -1) {
            System.out.println("Target is present"
                               + " at index "
                               + index);
        }
        else {
            System.out.println("Target is not present"
                               + " in the array");
        }
    }
}

Output:

Target is not present in the array

Reference: https://google.github.io/guava/releases/21.0/api/docs/com/google/common/primitives/Longs.html#lastIndexOf-long:A-long-