如何限制输入到文本框? [英] How to restrict input to textboxes?

问题描述

大家好.我正在通过文本框获取数据，但我想限制它.即，用户不能输入字符串或任何其他内容.我只希望数字字符在100到999之间.可以吗?

String  coursecode = Integer.parseInt(txtCourseCode.getText());
if(coursecode<100 || coursecode>999)
           {
               JOptionPane.showMessageDialog(null,"Incorrect Course Code");
           }

这是我代码的一小部分.

Thanx.

解决方案

验证是关键字.

无论您是创建自己的还是使用所提供的机制，都只需要在继续进行之前进行验证即可:

  public   class  CustomVerifier 扩展 InputVerifier {
     @ Override 
    公共 布尔 verify(JComponent输入){
    字符串 text =(((JTextField)input).getText();
    // 验证
     返回 true； // 如果可以
    // 返回false； //不好的时候
    }
} 

并添加到JTextfield:

 oTextField.setInputVerifier(新 CustomVerifier()); 

您还可以使用侦听器(propertyChange，focus)并在那里进行验证.


我需要提及的是您需要为此创建一个自定义JDialog吗?我猜不是.玩得开心.





具有侦听器的版本1:

 textField.addKeyListener(新 KeyAdapter(){
  // 适配器是侦听器的小版本"，
  // 它仅实现所需的功能
   @ Override 
  公共 无效 keyReleased(KeyEvent oEvent){
  // 不喜欢该事件，我们只需要它有机会做出反应即可.
    字符串 strContent = textField.getText();
    尝试 {
       int  i = Integer.parseInt(strContent); // 通过简单解析进行检查
      如果(i< = 0 || i> = 1000){// " )；
      }
      // 一切正常
    } 捕获(NumberFormatException oException){
      JOptionPane.showMessageDialog(null，" );
    }
});
  }
} 

带有InputVerifyer的Version2:

 textField.setInputVerifier(新 InputVerifier(){
   @ Override 
  公共 布尔 verify(JComponent输入){
    字符串 strContent = textField.getText();
    尝试 {
       int  i = Integer.parseInt(strContent); // 通过简单解析进行检查
      如果(i< = 0 || i> = 1000){// " )；
      }
      // 一切正常
    } 捕获(NumberFormatException oException){
      JOptionPane.showMessageDialog(null，" );
    }
    返回 true；
  }
}); 

希望Edit2有所帮助.您需要学习！
请购买一本书以获取此类信息，而无需知道关键字.

认为这确实可以解决.您可以尝试使用正则表达式将输入限制为仅数字，一旦完成，您就可以对值进行边界检查，这显然已经在代码中完成了.

Hello everyone. I am getting data via textbox but I want to restrict it. Namely, User can not enter character string or anything. I just want numeric characters between 100 and 999. Is it possible ?

String  coursecode = Integer.parseInt(txtCourseCode.getText());
if(coursecode<100 || coursecode>999)
           {
               JOptionPane.showMessageDialog(null,"Incorrect Course Code");
           }

this is a little part of my code.

Thanx.

解决方案

Validation is the keyword.

No matter if you create your own or use a mechanism that is provided, you just need to validate before you move on:

public class CustomVerifier extends InputVerifier {
    @Override
    public boolean verify(JComponent input) {
    String text = ((JTextField) input).getText();
    // verify
     return true; // if ok
    // return false; // when not ok   
    }
}

and add to the JTextfield:

oTextField.setInputVerifier(new CustomVerifier());

You can also use a listener (propertyChange, focus) and validate there.

EDIT:
Do I need to mention that you need to make a custom JDialog for this? I guess not. Have fun.



EDIT 2:

Version 1 with a Listener:

  textField.addKeyListener(new KeyAdapter() { 
  // Adapter is a "small version of a Listener", 
  // which does implement just the   needed functions
  @Override
  public void keyReleased(KeyEvent oEvent) { 
  // disgard the Event, we just need it to have a chance to react.
    String strContent = textField.getText();
    try { 
      int i = Integer.parseInt(strContent); // check by simple parsing
      if(i<=0 || i>=1000) { // number between 1 and 
        JOptionPane.showMessageDialog(null, "This number is <1 or   >999.");
      }
      // everything is ok
    } catch (NumberFormatException oException) {
      JOptionPane.showMessageDialog(null,"This is not even a number.");
    }
});
  }
}

Version2 with InputVerifyer:

textField.setInputVerifier(new InputVerifier() {
  @Override
  public boolean verify(JComponent input) {
    String strContent = textField.getText();
    try { 
      int i = Integer.parseInt(strContent); // check by simple parsing
      if(i<=0 || i>=1000) { // number between 1 and 
        JOptionPane.showMessageDialog(null, "This number is <1 or >999.");
      }
      // everything is ok
    } catch (NumberFormatException oException) {
      JOptionPane.showMessageDialog(null, "This is not even a number.");
    }
    return true;
  }
});

I hope Edit2 helps. You need to learn that!
Please buy a book to get such information without knowing the keywords.

Think this does count as a solution. You can try using Regular Expressions to restrict the input to numbers only and once that''s done you can have a bounds check on the values, which you already have done in your code apparently.

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