JFramePlay JTextArea中JPanel JFrame中的问题

Question

我有JTextAreaJPanel我想使用JScrollPane。我正在使用GridBagLayout。当我运行它似乎框架为JScrollPane腾出空间，但它不显示，任何帮助将不胜感激。我一直在试图研究docs.oracle页面，并在这里Add JScrollPane to a JPanel，但由于某种原因，它拒绝出现。

final JTextArea test= new JTextArea(5,30); 
test.setLineWrap(true); 
test.setWrapStyleWord(true); 
test.setEditable(false); 
JScrollPane spane = new JScrollPane(test); 
spane.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);   

JFrame frame = new JFrame(); 

frame.setSize(800, 250); 
frame.setTitle("test1"); 
frame.setLocation(300, 300); 
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
frame.setResizable(false); 
frame.getContentPane().add(spane); 

GridBagConstraints k = new GridBagConstraints(); 
k.gridx = 4; 
k.gridy = 5; 
a.setConstraints(spane,k); 
container.add(spane); 

Answer 1

您的可变容器是JPanel？我想你忘了调用add（）方法。但下面是我的建议代码。

import java.awt.Dimension; 
import java.awt.GridBagConstraints; 
import java.awt.GridBagLayout; 

import javax.swing.JFrame; 
import javax.swing.JPanel; 
import javax.swing.JScrollPane; 
import javax.swing.JTextArea; 
import javax.swing.ScrollPaneConstants; 
import javax.swing.SwingUtilities; 

public class MyScrollPane extends JPanel 
{ 

    public MyScrollPane() 
    { 
     GridBagConstraints k = new GridBagConstraints(); 
     k.gridx = 4; 
     k.gridy = 5; 



     final JTextArea test= new JTextArea(5, 30); 
     test.setLineWrap(true); 
     test.setWrapStyleWord(true); 
     test.setEditable(false); 

     JScrollPane spane = new JScrollPane(test); 
     spane.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS); 

     GridBagLayout gbl = new GridBagLayout(); 
     gbl.setConstraints(spane,k); 

     JPanel panel = new JPanel(gbl);  
     panel.add(spane); 
     add(panel); 

    } 


    private static void createAndShowGUI() 
    { 


     JFrame frame = new JFrame(); 
     frame.setSize(800, 250); 
     frame.setTitle("test1"); 
     frame.setLocation(300, 300); 
     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
     frame.setResizable(false); 
     frame.getContentPane().add(new MyScrollPane()); 



     frame.setVisible(true); 
    } 

    public static void main(String[] args) 
    { 
     SwingUtilities.invokeLater(new Runnable() { 

      @Override 
      public void run() 
      { 
       createAndShowGUI();    
      } 
     }); 
    } 

} 

Answer 2

我删除了代码的最后五行并将其更改了一点。我工作得很好。

public class MainFrame extends JFrame { 



private JTextArea test = new JTextArea(5, 30); 
private JScrollPane spane; 

public MainFrame() { 

    this.setSize(800, 250); 
    this.setTitle("test1"); 
    this.setLocation(300, 300); 
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
    this.setResizable(false); 

    test.setLineWrap(true); 
    test.setWrapStyleWord(true); 
    test.setEditable(false); 
    spane = new JScrollPane(test); 
    spane.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS); 

    this.getContentPane().add(spane); 

}