No parentheses in java

Question

I am learning Java and I have learned that methods use parentheses for passing parameters. However, I have also noticed that sometimes I see code which to me looks like a method but it does not have parentheses.

MyObject.something()

MyObject.somethingElse

Where somethingElse does not have parentheses. I assume this is similar to how an arrayList has the size method for getting its size:

myList.size()

whereas an array has length to get its size, which does not have parentheses:

myArray.length

Is my assumption correct? If not, what is the difference? This is probably an elementary question, but because of the amount of words I need to explain this problem, I have had trouble searching for it.

Answer 1

somethingElse is a property (data member), not a method. No code in the class is run when you access that member, unlike with a method where code in the class is run.

Here's an example:

public class Foo {

    public int bar;

    public Foo() {
        this.bar = 42;
    }

    public int getBlarg() {
        // code here runs when you call this method
        return 67;
    }

}

If you create a Foo object:

Foo f = new Foo();

...you can access the property bar without parens:

System.out.println(f.bar);        // "42"

...and you can call the method getBlarg using parens:

System.out.println(f.getBlarg()); // "67"

When you call getBlarg, the code in the getBlarg method runs. This is fundamentally different from accessing the data member foo.