Charset contains() method in Java with Examples

The contains() method is a built-in method of the java.nio.charset checks if a given charset is in another given charset. A charset X contains a charset Y if every character representable in Y is also representable in X. Every charset contains itself. However, this method computes an approximation of the containment relation. It implies that the function returns true if the given charset is there in the other charset. If it returns false, however, then it is not necessarily the case that the given charset is not contained in this charset.

Syntax:

public abstract boolean contains(Charset second)

Parameters: The function accepts a single mandatory parameter second which specifies the charset to be checked.

Return Value: The function returns a boolean value. It returns true if it contains the given charset, else it returns false.

Below is the implementation of the above function:

Program 1:

// Java program to demonstrate
// the above function

import java.nio.charset.Charset;
import java.util.Iterator;
import java.util.Map;

public class GFG {

    public static void main(String[] args)
    {
        // First charset
        Charset first = Charset.forName("ISO-2022-CN");

        // Second charset
        Charset second = Charset.forName("UTF-8");

        System.out.println(first.contains(second));
    }
}

Output:

false

Program 2:

// Java program to demonstrate
// the above function

import java.nio.charset.Charset;
import java.util.Iterator;
import java.util.Map;

public class GFG {

    public static void main(String[] args)
    {

        // First charset
        Charset first = Charset.forName("UTF-16");

        // Second charset
        Charset second = Charset.forName("UTF-8");

        System.out.println(first.contains(second));
    }
}

Output:

true

Reference: https://docs.oracle.com/javase/9/docs/api/java/nio/charset/Charset.html#contains-java.nio.charset.Charset-