單擊按鈕時是否將文本添加到JTextArea框？

Question

好的，所以我試圖弄清楚如何在GUI中單擊某個按鈕時將文本添加到TextArea中。 對於此當前問題，當我單擊“重置”按鈕時，我希望它顯示幾行我已經預先寫好的文本。 我不確定如何將其實現到我的applet中。

這是按鈕的代碼

public class DisplayButtonPanel2 extends JPanel{

//create buttons for reseting back to original data, displaying data and sorting data
JButton resebutton = new JButton("RESET");
JButton displaybutton = new JButton("DISPLAY");  
JButton sortbutton = new JButton("SORT"); 

//constructor 
public DisplayButtonPanel2()
{

      //create action listener object
  BListen listener = new BListen();

      //add action listen functionalty to buttons
  resebutton.addActionListener(listener);
  displaybutton.addActionListener(listener);
  sortbutton.addActionListener(listener);

     //add buttons to panel
  add(resebutton);
  add(displaybutton);
  add(sortbutton);

}

public class BListen implements ActionListener
{

   public void actionPerformed(ActionEvent event){

     if (event.getSource() == resebutton){

        JOptionPane.showMessageDialog(null,"reset Button Clicked");
        DisplayEmployeePanel displayemply = new DisplayEmployeePanel();
        displayemply.resetText();


     }

     else if(event.getSource() == displaybutton){

        JOptionPane.showMessageDialog(null,"display Button Clicked");
       // DisplayEmployeePanel displayemply = new DisplayEmployeePanel();
     }
     else if(event.getSource() == sortbutton){

        JOptionPane.showMessageDialog(null,"sort Button Clicked");
     }


  }

}

textArea的代碼

public class DisplayEmployeePanel extends JPanel{


//create a text area that will display employees

JTextArea employeetextarea = new JTextArea("~Company Employee's~", 20 ,30);          //textinarea, hieght, width



 //constructor
 public DisplayEmployeePanel()
 {

   employeetextarea.setEditable(false);   //will not be able to edit text in area

  String ns = "\nDisplay Employee Info BELOW";
  employeetextarea.append(ns);



  //add text area to panel
  add(employeetextarea);


}

public void resetText()
{

  String sn = "\nreset to original emmployee list";
  employeetextarea.append(sn);
  add(employeetextarea);
  System.out.println("reset text");///testing purposes

 }



 }//end class

EDIT *添加更多源代碼（如果有幫助的話），此代碼可用於創建框架

 public class CreateCompanyGUI extends JFrame{

 //constructor
 public CreateCompanyGUI()
 {
   super("Company Applet!");                                      //tittle
  setSize(800,800);                                              //set size  *careful when using pack*
  setLocationRelativeTo(null);                                   //places frame in middle of screen by default
  setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);                //how to close
  setLayout(new BorderLayout());                                 //set BorderLayout manager for this frame


  //create panels
  DisplayEmployeePanel dep = new DisplayEmployeePanel();
  //  DisplayEmployeePanel2 dep2 = new DisplayEmployeePanel2();
  DisplayButtonPanel dbp = new DisplayButtonPanel();
  DisplayButtonPanel2 dbp2 = new DisplayButtonPanel2();
 // DisplayListPanel dlp = new DisplayListPanel();


  //add panels to frame
  add(dep, BorderLayout.NORTH);
  add(dbp2, BorderLayout.CENTER);
  add(dbp, BorderLayout.SOUTH);
 // add(dlp, BorderLayout.EAST);
 // add(dep2, BorderLayout.CENTER);

  //pack (packs the window and creates appporiate size
  pack();
  //visible = TRUE (so we can see the frame)
  setVisible(true);


}



}//end class

用於創建GUI的代碼

public class CompanyApplet extends JApplet{

public static void main(String[] args)
{
     //create GUI for company applet
      new CreateCompanyGUI();


  }
 } 

Answer 1

    DisplayEmployeePanel displayemply = new DisplayEmployeePanel();
    displayemply.resetText();

您無法繼續創建新的DisplayEmployeePanel。 您要更新在GUI上可見的現有面板的文本區域。 這意味着DisplayButtonPanel2需要對DisplayEmployeePanel的引用。

因此，在創建兩個面板並將其添加到框架的代碼中，需要將DisplayEmployeedPanel作為參數傳遞給DisplayButtonPanel2。

或更簡單的解決方案是只使用一個類來創建兩個面板。 然后，該類中的所有方法都可以訪問該類中定義的所有組件。