String is immutable. What exactly is the meaning? [duplicate]

Answer 1

Hope the below code would clarify your doubts :

public static void testString() {
    String str = "Hello";
    System.out.println("Before String Concat: "+str);
    str.concat("World");
    System.out.println("After String Concat: "+str);
    StringBuffer sb = new StringBuffer("Hello");
    System.out.println("Before StringBuffer Append: "+sb);
    sb.append("World");
    System.out.println("After StringBuffer Append: "+sb);
}

Before String Concat: Hello
After String Concat: Hello
Before StringBuffer Append: Hello
After StringBuffer Append: HelloWorld