About calling instance methods

A reminder about the format of instance method calls.

About the method call format

--[Method name (argument)] for methods defined in the same instance --[Variable.method name (argument)] for the method defined in the instance --For static methods, [class name.method name (argument)]

Methods defined in the same instance

Test.java

public class Test {
  public void SayHello() {
    System.out.println("Hello World");
  }
  public void Display() {
    SayHello();
  }
}

Methods defined in different instances

Create a new instance and use the reference that contains the variable (hello.SayHello ();).

Hello.java

public class Hello{
  public void SayHello() {
    System.out.println("Hello World");
  }
}

Test.java

public class Test {
  public static void main(final String[] args) {
    Hello hello = new Hello();
    hello.SayHello();
  }
}

static method

Use class name references (Hello.SayHello ();).

Hello.java

public class Hello{
  public static void SayHello() {
    System.out.println("Hello World");
  }
}

Test.java

public class Test {
  public static void main(final String[] args) {
    Hello.SayHello();
  }
}

bonus

The ones without parentheses are the access to the fields of the instance.

References

Thorough capture Java SE11 Silver problem collection