Java Passing References and Point Class - Prof. Brian F. Hanks, Study notes of Javascript programming

Download Java Passing References and Point Class - Prof. Brian F. Hanks and more Study notes Javascript programming in PDF only on Docsity! CSIS 110 – Lecture 27 Last time we looked at some class methods, and what happens when the methods are called. Our last example looked what happens when the FP are a reference type. Let's look at Demo3.java And at PassingReferences.java All types are passed by value - it does not matter if the type of the formal parameter is a primitive type or a reference type. This means that if we change the value of a formal parameter, that change is not reflected back in the calling method. However, Let’s look at another example: PassingReferences2.java So, we can see that method f is working with a distinct JFrame, but method g is working with the reference that was passed to it. Repeat KEY POINT: If we change the value that is referenced by a reference type, that change is reflected back in the caller. This is a subtle but important distinction! Instance Methods Remember, instance methods require an object - we invoke instance methods using an object's name followed by '.' and the method name. String s = "Hello"; int l = s.length(); JFrame myFrame = new JFrame( "The Title" ); myFrame.setSize( 200, 300 ); Instance methods are defined without the keyword 'static': [public] <returnType> <Identifier> ( <Parameter List> ) <MethodBody> So: class method -- use static instance method - no static Let's create a class Point that represents points on a two dimensional grid. Each point has an x and y coordinate. What methods do Points need?