在lWUIT中，如何通過點擊後退命令來調用主MIDlet類？

Question

我的問題是如何通過點擊返回command來調用主MIDlet類？
假設MainMIDlet.java該類延伸Form並實現ActionListener和Aboutus.java該類擴展還包括Form與執行ActionListener。在這個類中，我沒有創建表單的對象。那麼在這個課上如何撥MainMIDlet課時點擊Commmand後退按鈕？

Answer 1

當您調用Aboutus.java時傳遞MainMIDlet表單實例。 例如，

MainMIDlet.java

public class MainMIDlet extends MIDlet implements ActionListener { 
    Form form = new form(); 
    ... 
    ... 

    public void actionPerformed(ActionEvent ae) 
     { 
      Command cmd = ae.getCommand(); 
      String cmdname= cmd.getCommandName(); 

      if (cmdname.equals("Aboutus")) 
      { 
       Aboutus aboutus = new Aboutus(form); // pass the current form 
       aboutus.show(); 
      } 
     } 
} 

Aboutus.java

public class Aboutus extends Form implements ActionListener { 

Form mainform; 

public Aboutus(Form form) { 
    this.mainform = form; 
    ... 
    ... 
    Command backCommand = new Command("Back",null,1); 
    this.setBackCommand(backCommand); 
} 
    ... 
    ... 

    public void actionPerformed(ActionEvent ae) 
     { 
      Command cmd = ae.getCommand(); 
      String cmdname= cmd.getCommandName(); 

      if (cmdname.equals("Back")) 
      { 
       mainform.showBack(); // show the Main Midlet form here 
      } 
     } 
}