从JTextArea获取密钥

Question

我想要做的所有事情如果我在JtextArea.automatically'}'中按'{'这个键，那么这也将是打印。

if(evt.KEY_PRESSED == '{') 

      System.out.print("}"); 

这是好吗？

Answer 1

听变为JTextComponent是那里的DocumentListener，如果您必须控制输入的字符，唱歌，空格字符或单词，以实现DocumentFilt呃

通知由编程语言（S），你必须使用双逃逸reservated个字符，

\\(而不是(

或

\\{，而不是{

否则你

Exception in thread "AWT-EventQueue-0" java.util.regex.PatternSyntaxException: 
Illegal repetition 

例如

import java.awt.*; 
import java.util.ArrayList; 
import java.util.List; 
import javax.swing.*; 
import javax.swing.event.*; 
import javax.swing.text.*; 

public class TextAreaTest extends JFrame { 

    private static final long serialVersionUID = 1L; 
    private JTextArea textArea; 

    public TextAreaTest() { 
     textArea = new JTextArea(); 
     textArea.setPreferredSize(new Dimension(60, 32)); 
     textArea.setOpaque(true); 
     textArea.setLineWrap(true); 
     textArea.setWrapStyleWord(true); 
     ((AbstractDocument) textArea.getDocument()).setDocumentFilter(new DocumentFilter() { 

      @Override 
      public void insertString(FilterBypass fb, int offset, String string, AttributeSet attr) throws BadLocationException { 
       string = string.replaceAll("\\{", "\\{}"); 
       super.insertString(fb, offset, string, attr); 
      } 

      @Override 
      public void replace(FilterBypass fb, int offset, int length, String text, AttributeSet attrs) throws BadLocationException { 
       text = text.replaceAll("\\{", "\\{}"); 
       //TODO must do something here 
       super.replace(fb, offset, length, text, attrs); 
      } 
     }); 

     textArea.getDocument().addDocumentListener(new DocumentListener() { 

      @Override 
      public void changedUpdate(DocumentEvent e) { 
       update(e); 
      } 

      @Override 
      public void insertUpdate(DocumentEvent e) { 
       update(e); 
      } 

      @Override 
      public void removeUpdate(DocumentEvent e) { 
       update(e); 
      } 

      private void update(DocumentEvent e) { 
       List<String> lines = getLines(textArea); 
       String lastLine = lines.get(lines.size() - 1); 
       int tabbedTextWidth = Utilities.getTabbedTextWidth(new Segment(
         lastLine.toCharArray(), 0, lastLine.length()), textArea.getFontMetrics(textArea.getFont()), 0, null, 0); 
       int lineHeight = getLineHeight(textArea); 
       if (lines.size() * lineHeight > textArea.getHeight() || tabbedTextWidth > textArea.getWidth()) { 
        System.out.println("Too big! Should refuse the update!"); 
       } 
      } 
     }); 

     getContentPane().add(textArea); 
    } 

    private static List<String> getLines(JTextArea textArea) { 
     int lineHeight = getLineHeight(textArea); 
     List<String> list = new ArrayList<String>(); 
     for (int num = 0;; num++) { 
      int i = textArea.viewToModel(new Point(0, num * lineHeight)); 
      int j = textArea.viewToModel(new Point(0, (num + 1) * lineHeight)); 
      if (i == 0 && j == 0) { 
       continue; 
      } 
      if (textArea.getDocument().getLength() == i && i == j) { 
       break; 
      } 
      String s = removeTrailingNewLine(textArea.getText().substring(i, j)); 
      list.add(s); 
      //System.out.println(i + " " + j + " = " + s); 
     } 
     return list; 
    } 

    private static int getLineHeight(JTextArea textArea) { 
     return textArea.getFontMetrics(textArea.getFont()).getHeight(); 
    } 

    private static String removeTrailingNewLine(String s) { 
     if (s.endsWith("\n")) { 
      return s.substring(0, s.length() - 1); 
     } else { 
      return s; 
     } 
    } 

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

      @Override 
      public void run() { 
       TextAreaTest test = new TextAreaTest(); 
       test.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
       test.pack(); 
       test.setVisible(true); 
      } 
     }); 
    } 
} 

Answer 2

我认为这是你正在寻找

if(evt.getID() == evt.KEY_PRESSED) { 

    if(evt.getKeyChar() == '{') { 
     System.out.print("}"); 
    } 
} 

测试什么，以及工作

Answer 3

您需要的键绑定 http://tips4java.wordpress.com/2008/10/10/key-bindings/ 和 http://docs.oracle.com/javase/tutorial/uiswing/misc/keybinding.html