访问第二类中另一类的Swing组件

Question

I have 2 classes Engine.java and Window.java . In the Window.java I have a button which will create instance of the Engine.java .

How can I pass Window.java to Engine.java ?

I know that I can use this, but this represent button at that moment of clicking button.

The reason is that I want to have access to all component of Window.java within Engine.java .

public class Engine{
   Window window;

   public Engine(Window en){
       window = en;
   }
   //rest of your code
}

public class Window(){

     btnDownload.addMouseListener(new MouseAdapter() {
        @Override
        public void mouseClicked(MouseEvent e) {
                 //At the point where you create the Engine
                  Engine en = new Engine(this);
                 //rest of your code
        }
}

Answer 1

Engine en = new Engine(Window.this); 

Answer 2

The reason is that I want to have access to all component of Window.java within Engine.java

Even if you do implement this, Engine will only be able to access those fields of Window which are declared public (unless they are in the same package, in which case, Engine will also be able to access all the default scoped Window methods).

Answer 3

Was going to suggest the Window.this, but if your only interested in the components, then why not:

public class Engine { 
    Component[] components; 

    public Engine(Component[] components){ 
        this.components = components;
    } 
}

public class Window() {

    JButton btnDownload;
    JButton btnUpload;

    public Window() {

        btnDownload = new JButton("Download");
        btnDownload.setName("Download");

        btnUpload = new JButton("Upload");
        btnUpload.setName("Upload");

        btnDownload.addMouseListener(new MouseAdapter() {  
            @Override  
            public void mouseClicked(MouseEvent e) {  
                   // create engine passing reference to only the components...
                   Engine en = new Engine( Window.this.getComponents() );  
                   // rest of your code  
            }  
    }

    public Component[] getComponents() {
        return new Component[] { btnDownload, btnUpload };
    }
}

Where Component is java.awt.Component, or you could use JComponent from swing.

If you did something like this then I guess each component would only be meaningful by name. So you could use the setName method (shown in Window constructor) on each component and do something in the engine to access them by name where needed - which is perhaps bad. Either way, you want a reference to the different components in the engine. You could either use an additional class or interface to expose the components if the above example does not fit.

public class MyParams {
    private Component download;
    private Component upload;

    public MyParams(Component download, Component upload) {
        this.upload = upload;
        this.download = download;
    }

    public Component getUpload() {
        return this.upload;
    }

    public Component getDownload() {
        return this.download;
    }
}

Then when creating Engine:

Engine e = new Engine( new MyParams( Window.this.btnDownload, Window.this.btnUpload) );

Engine Constructor:

public Engine(MyParams myParams) {
    this.myParams = myParams;
}

Access them in engine:

this.myParams.getUpload().setText( "Engine class has changed me" );

Totally agree with Cuga about passing in the Window reference. This kind of goes against the good class design encapsulation techniques.

Just food for thought

Answer 4

this should work...

public class Window(){

Windows ref = this;
btnDownload.addMouseListener(new MouseAdapter() {
        @Override
            public void mouseClicked(MouseEvent e) {
                       Engine en = new Engine(ref);
                 }