Phương thức insert() chèn dữ liệu vào một vị trí cụ thể của lớp StringBuffer

public class Example {
    public static void main(String[] args) {
        StringBuffer buffer = new StringBuffer("Hello World");

        // insert(int offset, boolean b)
        buffer.insert(5, true);
        System.out.println(buffer.toString()); // In ra "Hello trueWorld"

        // insert(int offset, char c)
        buffer.insert(11, '!');
        System.out.println(buffer.toString()); // In ra "Hello trueWorld!"

        // insert(int offset, char[] str)
        char[] charArray = {' ', 'J', 'a', 'v', 'a'};
        buffer.insert(12, charArray);
        System.out.println(buffer.toString()); // In ra "Hello trueWorld! Java"

        // insert(int index, char[] str, int offset, int len)
        char[] partialArray = {' ', 'E', 'x', 'a', 'm', 'p', 'l', 'e'};
        buffer.insert(17, partialArray, 1, 5); // Chèn "xampl"
        System.out.println(buffer.toString()); // In ra "Hello trueWorld! Java xampl"

        // insert(int dstOffset, CharSequence s)
        CharSequence charSeq = " Sequence";
        buffer.insert(22, charSeq);
        System.out.println(buffer.toString()); // In ra "Hello trueWorld! Java xampl Sequence"

        // insert(int dstOffset, CharSequence s, int start, int end)
        buffer.insert(22, charSeq, 1, 6); // Chèn "eque"
        System.out.println(buffer.toString()); // In ra "Hello trueWorld! Java xampl SequeSequence"

        // insert(int offset, double d)
        buffer.insert(27, 3.14);
        System.out.println(buffer.toString()); // In ra "Hello trueWorld! Java xampl Seque3.14Sequence"

        // insert(int offset, float f)
        buffer.insert(32, 2.71f);
        System.out.println(buffer.toString()); // In ra "Hello trueWorld! Java xampl Seque3.14Sequence2.71"

        // insert(int offset, int i)
        buffer.insert(37, 42);
        System.out.println(buffer.toString()); // In ra "Hello trueWorld! Java xampl Seque3.14Sequence2.7142"

        // insert(int offset, long l)
        buffer.insert(42, 123456789L);
        System.out.println(buffer.toString()); // In ra "Hello trueWorld! Java xampl Seque3.14Sequence2.7142123456789"

        // insert(int offset, Object obj)
        Object obj = new Object();
        buffer.insert(52, obj);
        System.out.println(buffer.toString()); // In ra "Hello trueWorld! Java xampl Seque3.14Sequence2.7142123456789java.lang.Object@..."

        // insert(int offset, String str)
        buffer.insert(72, " End");
        System.out.println(buffer.toString()); // In ra "Hello trueWorld! Java xampl Seque3.14Sequence2.7142123456789java.lang.Object@... End"
    }
}