StringBuffer insert() CharSequence in Java

insert(): This method is available in java.lang.StringBuffer class of Java.

Syntax:

StringBuffer java.lang.StringBuffer.insert(int dstOffset, CharSequence s, int start, int end)

This method takes four arguments, one of type CharSequence, and rest three are of type in as its parameters. This method inserts a subsequence of the specified CharSequence into this sequence. The subsequence of the argument s specified by start and end are inserted, in order, into this sequence at the specified destination offset, moving up any characters originally above that position.

The length of this sequence is increased by end - start.

Note:

1. The dstOffset argument must be greater than or equal to 0, and less than or equal to the length of this sequence.

2. The start argument must be nonnegative, and not greater than end.

3. The end argument must be greater than or equal to start, and less than or equal to the length of s.

4. If s is null, then this method inserts characters as if the s parameter was a sequence containing the four characters "null".

Parameters: Four parameters are required for this method.

dstOffset: the offset in this sequence.

s: the sequence to be inserted.

start: the starting index of the subsequence to be inserted.

end: the end index of the subsequence to be inserted.

Returns: a reference to this object.

Throws:

StringIndexOutOfBoundsException - if dstOffset is negative or greater than this.length(), or start or end are negative, or start is greater than end or end is greater than length().

For Example:

StringBuffer str = new StringBuffer("Hello World")

int dstOffset = 2

CharSequence s2 = "YYYYYYY"

int start = 2, end = 5

str.insert(dstOffset, s2, start, end) => It returns HeYYYllo World.

Approach 1: When the index is in the range.

Java

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

        StringBuffer str = new StringBuffer("Hello World");
        // insert CharSequence Range
        int dstOffset = 2;
        CharSequence s2 = "YYYYYYY";
        int start = 2, end = 5;
        str.insert(dstOffset, s2, start, end);
        System.out.println(str);
    }
}

Output:

HeYYYllo World

Approach 2: When the index is out of range.

Java

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

        StringBuffer str = new StringBuffer("Hello World");
        // insert CharSequence Range
        int dstOffset = -1;
        CharSequence s2 = "YYYYYYY";
        int start = 2, end = 5;
        str.insert(dstOffset, s2, start, end);
        System.out.println(str);
    }
}

Output:

Exception in thread "main" java.lang.StringIndexOutOfBoundsException: offset -1, length 11
	at java.base/java.lang.String.checkOffset(String.java:3704)
	at java.base/java.lang.AbstractStringBuilder.insert(AbstractStringBuilder.java:1293)
	at java.base/java.lang.StringBuffer.insert(StringBuffer.java:587)