super doubt

夏夏历险记

public class RoundButton extends JButton {
    
    public RoundButton (String label) {
        super (label); // What does super mean here?

Dimension size = getPreferredSize ()
setPreferredSize (size); // Do these two sentences not repeat?

cm200red

super(label)// is the constructor that calls the parent class (superclass).
As you can see from the method name, the purpose of getPreferredSize() is to return a value; and the role of setPreferredSize(size) is to set a value. It is obviously different.

极度zs

1. In the constructor with parameters, the child class needs to explicitly call the Super() method to call the parent class constructor to implement the default function.
2. One is setter() and one is getter(). Two attributes of the field

liuweiming

Lou Lou read the book to make up for the foundation

demon424

super(label);//super here is to call the inherited JButton class, super means to call the closest to the parent class.
Dimension size = getPreferredSize()/*Because it inherits the JButton class. Therefore, the getPreferredSize() function inherited from the parent class is called to obtain the value of size, and then copied to the object of the current class, which is a concept of encapsulation
setPreferredSize(size);//Don't these two sentences repeat?

xhbsea

extends does not inherit the constructor. You must write your own code! super(label); call the constructor of the parent class!

夏夏历险记

I am the landlord, what is the use of calling the parent class constructor here? Then, getPreferredSize() to get the value to size, and then set back with setPreferredSize(size), that is, take it out and send it back, what is the meaning What?

qwe6584109

It may be to call the constructor of the parent class to set the name of the button.

Did not strictly abide by the javaBean specifications:
Dimension size = getPreferredSize()
The value of the attribute preferredSize is assigned to the member variable size;

getPreferredSize();
setPreferredSize(size);
Set the attribute preferredSize to be readable and writable.