Question

I need to create a class with exactly the same methods as java.lang.String.

What is the best way to do this in Java?

I know that I can’t extend String class as it is final. I am not looking at solutions where I need to copy the source code of java.lang.String. For example, assume that I need the functionality length() within my custom class named MyString, which has a corresponding ‘myLength()` method.

What is the best way to implement myLength()?

I am not looking at various algorithms to find out the length of a string but to reuse String‘s length() method. Now once I have MyString class ready, I should be able to use it anywhere for my custom manipulations.

Answer 1

From your question it sounds like the thing you are looking for is simple delegation:

class MyString {

  String delegate; // The actual string you delegate to from your class

  public MyString(String delegate) {
    this.delegate = delegate; // Assign the string that backs your class
  }

  int length() {
    return delegate.length(); // Delegate the method call to the string
  }

  // other methods that delegate to the string field
}