StringBuffer getChars() method in Java with Examples

The getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin) method of StringBuffer class copies the characters starting at the index:srcBegin to index:srcEnd-1 from actual sequence into an array of char passed as parameter to function.

• The characters are copied into the array of char dst[] starting at index:dstBegin and ending at index:dstbegin + (srcEnd-srcBegin) – 1.
• The first character to be copied to array is at index srcBegin and the last character to be copied is at index srcEnd-1.
• The total number of characters to be copied is equal to srcEnd-srcBegin.

Syntax:

public void getChars(int srcBegin, int srcEnd, 
                          char[] dst, int dstBegin)

Parameters: This method takes four parameters:

• srcBegin: int value represents index on which the copying is to be started.
• srcEnd: int value represents index on which the copying is to be stopped.
• dst: array of char represents the array to copy the data into.
• dstBegin: int value represents index of dst array to start pasting the copied data.

Returns: This method returns nothing. Exception: This method throws StringIndexOutOfBoundsException if:

• srcBegin < 0
• dstBegin < 0
• srcBegin > srcEnd
• srcEnd > this.length()
• dstBegin+srcEnd-srcBegin > dst.length

Below programs demonstrate the getChars() method of StringBuffer Class: Example 1:

Java

// Java program to demonstrate
// the getChars() Method.

import java.util.*;

class GFG {
    public static void main(String[] args)
    {

        // create a StringBuffer object
        // with a String pass as parameter
        StringBuffer
            str
            = new StringBuffer("Geeks For Geeks");

        // print string
        System.out.println("String = "
                           + str.toString());

        // create a char Array
        char[] array = new char[15];

        // initialize all character to .(dot).
        Arrays.fill(array, '.');

        // get char from index 0 to 9
        // and store in array start index 3
        str.getChars(0, 9, array, 1);

        // print char array after operation
        System.out.print("char array contains : ");

        for (int i = 0; i < array.length; i++) {
            System.out.print(array[i] + " ");
        }
    }
}

Output:

String = Geeks For Geeks
char array contains : . G e e k s   F o r . . . . .

Example 2: To demonstrate StringIndexOutOfBoundsException. 

Java

// Java program to demonstrate
// exception thrown by the getChars() Method.

import java.util.*;

class GFG {
    public static void main(String[] args)
    {

        // create a StringBuffer object
        // with a String pass as parameter
        StringBuffer
            str
            = new StringBuffer("Contribute Geeks");

        // create a char Array
        char[] array = new char[10];

        // initialize all character to $(dollar sign).
        Arrays.fill(array, '$');

        try {

            // if start is greater then end
            str.getChars(2, 1, array, 0);
        }

        catch (Exception e) {
            System.out.println("Exception: " + e);
        }
    }
}

Output:

Exception: java.lang.StringIndexOutOfBoundsException: srcBegin > srcEnd

References: https://docs.oracle.com/javase/10/docs/api/java/lang/StringBuffer.html#getChars(int, int, char%5B%5D, int)