字母验证在JTextField中使用的Java Swing

Question

可能重复：
I didn't get a proper output for this code, plz send me a correct code

嗨当​​我进入JTextField1它需要验证的值应该只接受字母和并不比其他当我输入字母以外的值时，它不应该进入JTextField1并以标签格式给出消息，因为只有在按下其他键时才能输入字母。
我用 ===============

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

public class valid extends JFrame { 
    perform1 per1=new perform1(); 
    String num1="Alpha"; 
    String num2="Numeric"; 
    String num3="Alphanumeric"; 
    Container contentPane = getContentPane(); 
    JPanel jp=new JPanel(new GridLayout(2, 2)); 
    JLabel label1=new JLabel("STUDENT NAME", JLabel.LEFT); 
    JLabel label2=new JLabel("REG NO", JLabel.LEFT); 
    JTextField text1=new JTextField(15); 
    JTextField text2=new JTextField(15); 
    public valid(){ 
     text1.addKeyListener(new KeyAdapter() { 
      public void keyReleased(KeyEvent e) { 
       per1.dis(text1, e, num1); 

      } 
     }); 
     text2.addKeyListener(new KeyAdapter() { 
      public void keyReleased(KeyEvent e) { 
       per1.dis(text2, e, num2); 
      } 
     }); 
     setLayout(new FlowLayout(FlowLayout.CENTER)); 
     jp.add(label1); 
     jp.add(text1); 
     jp.add(label2); 
     jp.add(text2); 
     contentPane.add("Center", jp); 
     setSize(400, 300); 
     setVisible(true); 
    } 
    public static void main(String ar[]) 
    { 
     new valid(); 
    } 
} 
class perform1{ 
public void dis(JTextField PTxtCtrl,KeyEvent PKeyvalue,String PTempStr){ 
    JLabel error=new JLabel(); 
    //JTextField text=new JTextField(); 
    String TmpCurntStr; 
    String TmpConvStr; 
    value val = value.valueOf(PTempStr); 

    switch(val){ 
     case Alpha: 
      if((PKeyvalue.getKeyChar()>='a'&& PKeyvalue.getKeyChar()<='z')|| 
      (PKeyvalue.getKeyCode()==PKeyvalue.VK_DELETE)|| 
      (PKeyvalue.getKeyCode()==PKeyvalue.VK_BACK_SPACE)) 
      { 
      TmpCurntStr=PTxtCtrl.getText(); 
      TmpConvStr=TmpCurntStr.toUpperCase(); 
      PTxtCtrl.setText(TmpConvStr); 
      //PTxtCtrl.setEditable(true); 
      //error.setText(""); 
      }else{ 
      //PTxtCtrl.setEditable(false); 
      //error.setText("* Enter only numeric digits(0-9)"); 

      } 
      break; 
     case Numeric: 
      if((PKeyvalue.getKeyChar()>='0'&& PKeyvalue.getKeyChar()<='9')|| 
      (PKeyvalue.getKeyCode()==PKeyvalue.VK_DELETE)|| 
      (PKeyvalue.getKeyCode()==PKeyvalue.VK_BACK_SPACE)) 
      { 
      TmpCurntStr=PTxtCtrl.getText(); 
      System.out.println("hai"); 
      }else{ 
       JOptionPane.showMessageDialog(null,"Only numeric"); 
      } 
      break; 
     case Alphanumeric: 
      break; 
    } 
} 
    enum value{ 
    Alpha, 
    Numeric, 
    Alphanumeric 
} 
} 

Answer 1

可以使用的JFormattedTextField或平常的JTextField但指定自己的DocumentFilter的代码。

Answer 2

如果你想删除不是字母的字符，你可以用replaceAll来替换它们。例如：

TmpCurntStr=PTxtCtrl.getText(); 
TmpConvStr=TmpConvStr.replaceAll("[^a-zA-Z]", ""); 
PTxtCtrl.setText(TmpConvStr); 

Answer 3

我有正确的检查它，如果你不明白，那么让我知道。

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

public class valid extends JFrame { 
    perform1 per1=new perform1(); 
    String num1="Alpha"; 
    String num2="Numeric"; 
    String num3="Alphanumeric"; 
    Container contentPane = getContentPane(); 
    JPanel jp=new JPanel(new GridLayout(2, 2)); 
    JLabel label1=new JLabel("STUDENT NAME", JLabel.LEFT); 
    JLabel label2=new JLabel("REG NO", JLabel.LEFT); 
    JTextField text1=new JTextField(15); 
    JTextField text2=new JTextField(15); 
    public valid(){ 
     text1.addKeyListener(new KeyAdapter() { 
      public void keyReleased(KeyEvent e) { 
       /** 
       * check ASCII value of character enter in text1 
       * if it not fall in alphabets then send Alphanumeric 
       * 
       */ 
       char text = e.getKeyChar(); 
       if(text >= 65 && text <= 90 || text >= 97 && text <= 122){ 
        per1.dis(text1, e, num1); 
       }else{ 
        per1.dis(text1, e, num3); 
       } 

      } 
     }); 
     text2.addKeyListener(new KeyAdapter() { 
      public void keyReleased(KeyEvent e) { 
       per1.dis(text2, e, num2); 
      } 
     }); 
     setLayout(new FlowLayout(FlowLayout.CENTER)); 
     jp.add(label1); 
     jp.add(text1); 
     jp.add(label2); 
     jp.add(text2); 
     contentPane.add("Center", jp); 
     setSize(400, 300); 
     setVisible(true); 
    } 
    public static void main(String ar[]) 
    { 
     new valid(); 
    } 
} 
class perform1{ 
public void dis(JTextField PTxtCtrl,KeyEvent PKeyvalue,String PTempStr){ 
    JLabel error=new JLabel(); 
    //JTextField text=new JTextField(); 
    String TmpCurntStr; 
    String TmpConvStr; 
    value val = value.valueOf(PTempStr); 

    switch(val){ 
     case Alpha: 
      if((PKeyvalue.getKeyChar()>='a'&& PKeyvalue.getKeyChar()<='z')|| 
      (PKeyvalue.getKeyCode()==PKeyvalue.VK_DELETE)|| 
      (PKeyvalue.getKeyCode()==PKeyvalue.VK_BACK_SPACE)) 
      { 
      TmpCurntStr=PTxtCtrl.getText(); 
      TmpConvStr=TmpCurntStr.toUpperCase(); 
      PTxtCtrl.setText(TmpConvStr); 
      //PTxtCtrl.setEditable(true); 
      //error.setText(""); 
      }else{ 
      //PTxtCtrl.setEditable(false); 
      //error.setText("* Enter only numeric digits(0-9)"); 

      } 
      break; 
     case Numeric: 
      if((PKeyvalue.getKeyChar()>='0'&& PKeyvalue.getKeyChar()<='9')|| 
      (PKeyvalue.getKeyCode()==PKeyvalue.VK_DELETE)|| 
      (PKeyvalue.getKeyCode()==PKeyvalue.VK_BACK_SPACE)) 
      { 
      TmpCurntStr=PTxtCtrl.getText(); 
      System.out.println("hai"); 
      }else{ 
       JOptionPane.showMessageDialog(null,"Only numeric"); 
       PTxtCtrl.setText(""); 
      } 
      break; 
     case Alphanumeric: 
//   System.err.println("check"); 
      /** 
      * if it send Alphanumeric then give a pop up message 
      */ 
      JOptionPane.showMessageDialog(null,"Only Alphabets"); 
      PTxtCtrl.setText(""); 
      break; 
    } 
} 
    enum value{ 
    Alpha, 
    Numeric, 
    Alphanumeric 
} 
}