一段用NetBeans生成的 有些没用的直接忽略就可以的 问题在前十来行的 e.consume(); 是这样的 本来是文本框加个事件不是数字不能输入 结果出现了 什么都能输入 而且退格左右移动光标都废了 是否数字判断也没问题 !
package cn.itcast_07;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
/**
*
@author Hunter
*/
public class NewJFrame extends javax.swing.JFrame {
public NewJFrame() {
initComponents();
onlynum();
init();
}
public void onlynum() {
this.firstNumber.addKeyListener(new KeyAdapter() {
@Override
public void keyPressed(KeyEvent e) {
char ch = e.getKeyChar();
if (!(ch > '0' && ch < '9')) {
e.consume();
}
}
});
this.secondNumber.addKeyListener(new KeyAdapter() {
@Override
public void keyPressed(KeyEvent e) {
char ch = e.getKeyChar();
if (!(ch > '0' && ch < '9')) {
e.consume();
}
}
});
}
private void init() {
this.setTitle("模拟四呢运算");
}
private void initComponents() {
jLabel1 = new javax.swing.JLabel();
jLabel2 = new javax.swing.JLabel();
jLabel3 = new javax.swing.JLabel();
firstNumber = new javax.swing.JTextField();
secondNumber = new javax.swing.JTextField();
result = new javax.swing.JTextField();
operator = new javax.swing.JComboBox();
jButton1 = new javax.swing.JButton();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
jLabel1.setText("第一个数");
jLabel2.setText("第二个数");
jLabel3.setText("结果");
operator.setModel(new javax.swing.DefaultComboBoxModel(new String[] { "+", "-", "*", "/" }));
jButton1.setText("计算");
jButton1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton1ActionPerformed(evt);
}
});
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(25, 25, 25)
.addComponent(firstNumber)
.addGap(20, 20, 20))
.addGroup(layout.createSequentialGroup()
.addGap(37, 37, 37)
.addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 78, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 26, Short.MAX_VALUE)))
.addComponent(operator, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(18, 18, 18)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(0, 22, Short.MAX_VALUE)
.addComponent(jLabel2, javax.swing.GroupLayout.PREFERRED_SIZE, 57, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(75, 75, 75)
.addComponent(jLabel3)
.addGap(62, 62, 62))
.addGroup(layout.createSequentialGroup()
.addComponent(secondNumber, javax.swing.GroupLayout.PREFERRED_SIZE, 92, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addComponent(jButton1, javax.swing.GroupLayout.DEFAULT_SIZE, 79, Short.MAX_VALUE)
.addComponent(result))
.addGap(0, 0, Short.MAX_VALUE))))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(33, 33, 33)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 28, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jLabel2)
.addComponent(jLabel3))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(firstNumber, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(secondNumber, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(result, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(operator, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 28, Short.MAX_VALUE)
.addComponent(jButton1)
.addContainerGap())
);
pack();
}// //GEN-END:initComponents
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_jButton1ActionPerformed
//获取第一个操作数
String firstNumberString = this.firstNumber.getText().trim();
//获取第二个操作数
String secondNumberString = this.secondNumber.getText().trim();
//获取运算符
String operatorString = this.operator.getSelectedItem().toString();
////第一个数转成int
int firstNumber = Integer.parseInt(firstNumberString);
//第二个数转成int
int secondNumber = Integer.parseInt(secondNumberString);
int resultNumber = 0;
switch (operatorString) {
case "+":
resultNumber = firstNumber + secondNumber;
break;
case "-":
resultNumber = firstNumber - secondNumber;
break;
case "*":
resultNumber = firstNumber * secondNumber;
break;
case "/":
resultNumber = firstNumber / secondNumber;
break;
}
this.result.setText(String.valueOf(resultNumber));
}//GEN-LAST:event_jButton1ActionPerformed
/**
@param args the command line arguments
*/
public static void main(String args[]) {
try {
for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
if ("Nimbus".equals(info.getName())) {
javax.swing.UIManager.setLookAndFeel(info.getClassName());
break;
}
}
} catch (ClassNotFoundException ex) {
java.util.logging.Logger.getLogger(NewJFrame.class
.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(NewJFrame.class
.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(NewJFrame.class
.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(NewJFrame.class
.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
//
/* Create and display the form */
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new NewJFrame().setVisible(true);
}
});
}
// Variables declaration - do not modify//GEN-BEGIN:variables
private javax.swing.JTextField firstNumber;
private javax.swing.JButton jButton1;
private javax.swing.JLabel jLabel1;
private javax.swing.JLabel jLabel2;
private javax.swing.JLabel jLabel3;
private javax.swing.JComboBox operator;
private javax.swing.JTextField result;
private javax.swing.JTextField secondNumber;
// End of variables declaration//GEN-END:variables
}
你的想法是正确的，通过判断按下的键是否是0-9的值在进行输入，但是你的逻辑是错误的，你的判断方法中先不说对不对，你的if是当输入的字符不是0-9时什么也不错继续进行，这样就跟你想的完全相反了，按我的理解当不是0-9时要做些什么处理的，而你用consume方法是没有意义的。
要不是你理解的consume有误，要不就是逻辑写反了。
其次，你这样判断是不正确的，这个KeyEvent只是在你按下的时候触发无法满足你的需求，即使你改了输入的Key值也无法阻止摁下的键输入到文本框中；
最后告诉你在文本框中Java是提供了Document接口来实现特定内容的输入的，比如数字，你可以参考我下面改写的你的方法，这样就只能输入正整数了，需要输入浮点数或者负数只要在for循环中更改条件即可。
public void onlynum() {
this.firstNumber.setDocument(new PlainDocument() {
@Override
public void insertString(int offs, String str, AttributeSet a)
throws BadLocationException {
// TODO Auto-generated method stub
for (int i = 0; i < str.length(); i++) {
if (str.charAt(i) < '0' || str.charAt(i) > '9') {
return;
}
}
super.insertString(offs, str, a);
}
});
this.secondNumber.setDocument(new PlainDocument() {
@Override
public void insertString(int offs, String str, AttributeSet a)
throws BadLocationException {
// TODO Auto-generated method stub
for (int i = 0; i < str.length(); i++) {
if (str.charAt(i) < '0' || str.charAt(i) > '9') {
return;
}
}
super.insertString(offs, str, a);
}
});
this.firstNumber.addKeyListener(new KeyAdapter() {
@Override
public void keyPressed(KeyEvent e) {
char ch = e.getKeyChar();
if (!(ch > '0' && ch < '9')) {
e.consume();
}
}
});
this.secondNumber.addKeyListener(new KeyAdapter() {
@Override
public void keyPressed(KeyEvent e) {
char ch = e.getKeyChar();
if (!(ch > '0' && ch < '9')) {
e.consume();
}
}
});
}
在事件处理中加上一个断点调试下。
手机上看不了，回家帮你看看
断点处理看看，具体是那一步有问题了？可以先删除一部分不重要的代码，看能不能恢复你要的效果，再一点点添加