MessageFormat applyPattern() method in Java with Example

The applyPattern() method of java.text.MessageFormat class is used to set the new pattern text for current MessageFormat by overriding the current FormatElement, FormatType and FormatStyle. Syntax:

public void applyPattern(String newPattern)

Parameter: This method takes string newPattern as parameter which is the new text pattern for this MessageFormat object. Return Value: This method returns nothing. Exception: This method throws NullPointerException if the specified newPattern is null. Below are the examples to illustrate the applyPattern() method: Example 1:

Java

// Java program to demonstrate
// applyPattern() method

import java.text.*;
import java.util.*;
import java.io.*;

public class GFG {
    public static void main(String[] argv)
    {
        // creating and initializing  MessageFormat
        MessageFormat mf
            = new MessageFormat("{0, number, #}, {0, number, #.##}, {0, number}");

        // display the result
        System.out.println("old pattern : "
                           + mf.toPattern());

        // applying new string pattern
        // to this MessageFormat Object
        // using applyPattern() method
        mf.applyPattern("{0, time, #}");

        // display the result
        System.out.println("\nnew pattern : "
                           + mf.toPattern());
    }
}

Output:

old pattern : {0, number, #}, {0, number, #0.##}, {0, number}

new pattern : {0, date, #}

Example 2:

Java

// Java program to demonstrate
// applyPattern() method

import java.text.*;
import java.util.*;
import java.io.*;

public class GFG {
    public static void main(String[] argv)
    {
        try {
            // creating and initializing MessageFormat
            MessageFormat mf
                = new MessageFormat("{0, date, #}, {1, time, #}, {0, number}");

            // display the result
            System.out.println("old pattern : "
                               + mf.toPattern());

            // applying new string pattern
            // to this MessageFormat Object
            // using applyPattern() method
            mf.applyPattern(null);

            // display the result
            System.out.println("\nnew pattern : "
                               + mf.toPattern());
        }
        catch (NullPointerException e) {
            System.out.println("\nString is Null");
            System.out.println("Exception thrown : " + e);
        }
    }
}

Output:

old pattern : {0, date, #}, {1, date, #}, {0, number}

String is Null
Exception thrown : java.lang.NullPointerException

Reference: https://docs.oracle.com/javase/9/docs/api/java/text/MessageFormat.html#applyPattern-java.lang.String-