At compile time, if either operand of a + operator is a String object, then the compiler recognizes that it is in a string context. : String class « Utility Classes « SCJP

1. SCJP
2. Utility Classes
3. String class

public class MainClass {
  public static void main(String[] argv) {

    System.out.println("" + new MyClass());
  }
}

class MyClass {

  public String toString() {
    return "MyClass";
  }
}

MyClass