Question

好的，所以当我在GUI中点击某个按钮时，我想弄清楚如何在TextArea中添加文本。对于这个当前的问题，当我单击重置按钮时，我希望它显示我已经预先编写的几行文本。我不确定如何将其实现到我的applet中。

这是我的按钮代码

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的代码

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

编辑*添加更多源代码，如果有帮助，这段代码用于创建框架

 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

创建GUI的代码

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();

您无法继续创建新的DisplayEmployeePanel。您想要更新GUI上可见的现有面板的textarea。然后意味着DisplayButtonPanel2需要对DisplayEmployeePanel的引用。

因此，在您创建两个面板并将其添加到框架的代码中，您需要将DisplayEmployeedPanel作为parmameter传递给DisplayButtonPanel2。

或者更简单的解决方案是只有一个创建两个面板的类。然后该类中的所有方法都可以访问类中定义的所有组件。

单击按钮时向JTextArea框添加文本？

1 个答案: