如何在JTextArea上添加JScrollPane？

这里，如果我使用的是构造函数，那么它什么也不做&我不想用setBounds（）添加我的scrollpane，所以任何人都可以帮助我摆脱这个问题... 我的代码是...如何在JTextArea上添加JScrollPane？

import java.awt.*; 
import java.awt.event.*; 
import javax.swing.*; 

class MyMenu implements ActionListener 
{ 

    JTextField tf=new JTextField(); 
    JFrame jf=new JFrame("My Menu"); 
    JMenuBar menubar; 
    JMenu menu,SubMenu; 
    JMenuItem menuItem,exit; 
    JScrollPane jp; 
    JRadioButtonMenuItem rbMenuItem; 
    JCheckBoxMenuItem cbMenuItem; 

    MyMenu() 
    { 
     jf.add(tf); 
     menubar=new JMenuBar(); 
     menu=new JMenu("First Menu"); 
     menu.setMnemonic(KeyEvent.VK_F); 
     menubar.add(menu); 


     jp=new JScrollPane() 
     jf.add(jp); 
     menuItem=new JMenuItem("Ank"); 
     //menuItem.setActionCommand("Ank"); 
     menuItem.addActionListener(this); 
     KeyStroke i=KeyStroke.getKeyStroke(KeyEvent.VK_1,ActionEvent.CTRL_MASK); 
     menuItem.setAccelerator(i); 
     menu.add(menuItem); 

     //a grp of radioButton menu items 
     ButtonGroup group=new ButtonGroup(); 
     rbMenuItem =new JRadioButtonMenuItem("Radio Button menu item"); 
     rbMenuItem.setSelected(true); 
     rbMenuItem.setMnemonic(KeyEvent.VK_R); 
     group.add(rbMenuItem); 
     rbMenuItem=new JRadioButtonMenuItem("Another one"); 
     rbMenuItem.setMnemonic(KeyEvent.VK_O); 
     group.add(rbMenuItem); 
     menu.addSeparator(); 

     cbMenuItem=new JCheckBoxMenuItem("A check box menu item"); 
     cbMenuItem.setMnemonic(KeyEvent.VK_C); 
     menu.add(cbMenuItem); 
     cbMenuItem=new JCheckBoxMenuItem("ANother1"); 
     cbMenuItem.setMnemonic(KeyEvent.VK_H); 
     menu.add(cbMenuItem); 

     //a submenu 
     menu.addSeparator(); 
     SubMenu=new JMenu("A SUbmenu"); 
     SubMenu.setMnemonic(KeyEvent.VK_S); 

     menuItem=new JMenuItem(" Item q"); 

     menuItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_2,ActionEvent.ALT_MASK)); 
     SubMenu.add(menuItem); 

     menuItem=new JMenuItem("Another q"); 
     SubMenu.add(menuItem); 
     menu.add(SubMenu); 
     exit=new JMenuItem("EXIT"); 
     exit.addActionListener(this); 
     menu.add(exit); 

     //..Build a second menu. 
     menu =new JMenu("another Menu"); 
     menu.setMnemonic(KeyEvent.VK_N); 
     menubar.add(menu); 
     jf.setJMenuBar(menubar); 
     jf.setSize(300,400); 
     jf.setVisible(true); 
    } 

    public void actionPerformed(ActionEvent e) 
    { 
     if(e.getActionCommand().equals("EXIT")) 
     { 
      System.exit(0); 
     } 

     if(e.getActionCommand().equals("Ank1")) 
     { 
      tf.setText("helloo"); 
     } 
    } 

    public static void main(String... c) 
    { 
     new MyMenu(); 
    } 
}

另外，如果我使用一个构造函数并将JTextField传入它，那么什么都不会发生。

来源

2015-04-03 Kapil Arora

1-在滚动条中没有任何东西; 2-你添加textField和scrollPane到相同的位置（隐藏文本框）。这是因为该框架默认使用BorderLayout – MadProgrammer 2015-04-03 02:46:11

JTextArea area = new JTextArea（）; JScrollPane jp; // .......... jp = new JScrollPane（area）; jf.add（jp）;什么都没发生 – 2015-04-03 02:53:32

似乎工作没关系，我...

改变了... ...

jf.add(tf);

到

jf.add(tf, BorderLayout.NORTH);

和

jp = new JScrollPane();

到

jp = new JScrollPane(new JTextArea(10, 20));

Runnable的例子...

import java.awt.BorderLayout; 
import java.awt.EventQueue; 
import java.awt.event.ActionEvent; 
import java.awt.event.ActionListener; 
import java.awt.event.KeyEvent; 
import javax.swing.ButtonGroup; 
import javax.swing.JCheckBoxMenuItem; 
import javax.swing.JFrame; 
import javax.swing.JMenu; 
import javax.swing.JMenuBar; 
import javax.swing.JMenuItem; 
import javax.swing.JRadioButtonMenuItem; 
import javax.swing.JScrollPane; 
import javax.swing.JTextArea; 
import javax.swing.JTextField; 
import javax.swing.KeyStroke; 
import javax.swing.UIManager; 
import javax.swing.UnsupportedLookAndFeelException; 

class MyMenu implements ActionListener { 

    JTextField tf = new JTextField(); 
    JFrame jf = new JFrame("My Menu"); 
    JMenuBar menubar; 
    JMenu menu, SubMenu; 
    JMenuItem menuItem, exit; 
    JScrollPane jp; 
    JRadioButtonMenuItem rbMenuItem; 
    JCheckBoxMenuItem cbMenuItem; 

    MyMenu() { 
     jf.add(tf, BorderLayout.NORTH); 
     menubar = new JMenuBar(); 
     menu = new JMenu("First Menu"); 
     menu.setMnemonic(KeyEvent.VK_F); 
     menubar.add(menu); 

     jp = new JScrollPane(new JTextArea(10, 20)); 
     jf.add(jp); 
     menuItem = new JMenuItem("Ank"); 
     //menuItem.setActionCommand("Ank"); 
     menuItem.addActionListener(this); 
     KeyStroke i = KeyStroke.getKeyStroke(KeyEvent.VK_1, ActionEvent.CTRL_MASK); 
     menuItem.setAccelerator(i); 
     menu.add(menuItem); 

     //a grp of radioButton menu items 
     ButtonGroup group = new ButtonGroup(); 
     rbMenuItem = new JRadioButtonMenuItem("Radio Button menu item"); 
     rbMenuItem.setSelected(true); 
     rbMenuItem.setMnemonic(KeyEvent.VK_R); 
     group.add(rbMenuItem); 
     rbMenuItem = new JRadioButtonMenuItem("Another one"); 
     rbMenuItem.setMnemonic(KeyEvent.VK_O); 
     group.add(rbMenuItem); 
     menu.addSeparator(); 

     cbMenuItem = new JCheckBoxMenuItem("A check box menu item"); 
     cbMenuItem.setMnemonic(KeyEvent.VK_C); 
     menu.add(cbMenuItem); 
     cbMenuItem = new JCheckBoxMenuItem("ANother1"); 
     cbMenuItem.setMnemonic(KeyEvent.VK_H); 
     menu.add(cbMenuItem); 

     //a submenu 
     menu.addSeparator(); 
     SubMenu = new JMenu("A SUbmenu"); 
     SubMenu.setMnemonic(KeyEvent.VK_S); 

     menuItem = new JMenuItem(" Item q"); 
     menuItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_2, ActionEvent.ALT_MASK)); 
     SubMenu.add(menuItem); 

     menuItem = new JMenuItem("Another q"); 
     SubMenu.add(menuItem); 
     menu.add(SubMenu); 
     exit = new JMenuItem("EXIT"); 
     exit.addActionListener(this); 
     menu.add(exit); 

     //..Build a second menu. 
     menu = new JMenu("another Menu"); 
     menu.setMnemonic(KeyEvent.VK_N); 
     menubar.add(menu); 
     jf.setJMenuBar(menubar); 
     jf.pack(); 
     jf.setVisible(true); 
    } 

    public void actionPerformed(ActionEvent e) { 
     if (e.getActionCommand().equals("EXIT")) { 
      System.exit(0); 
     } 
     if (e.getActionCommand().equals("Ank1")) { 
      tf.setText("helloo"); 
     } 
    } 

    public static void main(String... c) { 
     EventQueue.invokeLater(new Runnable() { 
      @Override 
      public void run() { 
       try { 
        UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName()); 
       } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) { 
        ex.printStackTrace(); 
       } 

       new MyMenu(); 
      } 
     }); 
    } 
}

采取在How to Use Scroll Panes定睛一看，How to Use BorderLayout更多细节

来源

2015-04-03 03:31:20 MadProgrammer

尝试以下操作：

JTextArea tf = new JTextArea(10, 20); 

JScrollPane scrollBar = new JScrollPane(tf);

您只需要添加滚动条到JFrame。

来源

2015-09-11 07:17:28

如何在JTextArea上添加JScrollPane？

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