每次更改时自动更新 jTextFields 的总和（Java）
[英]Updating the sum of jTextFields automatically everytime they change (Java)
问题描述
作为我的 Java 学习的一部分，我使用 netbeans 制作了一个 jForm，其中包含三个 jTextField，供用户输入一些数字，然后这些数字的总和显示在另一个 jTextField 中。 这当然非常简单，但我希望能够在没有任何按钮的情况下做到这一点。 每次修改 3 个文本字段中的任何一个时，我都不知道如何“更新”总和。 谁能帮我？
这是我的代码（表单是在设计模式下使用 netbeans 完成的）：
package sumfields;
public class Frame extends javax.swing.JFrame {
public Frame() {
initComponents();
}
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
n1 = new javax.swing.JTextField();
n2 = new javax.swing.JTextField();
n3 = new javax.swing.JTextField();
sum = new javax.swing.JTextField();
jLabel1 = new javax.swing.JLabel();
jLabel2 = new javax.swing.JLabel();
jLabel3 = new javax.swing.JLabel();
jLabel5 = new javax.swing.JLabel();
jButton1 = new javax.swing.JButton();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
jLabel1.setText("n1");
jLabel2.setText("n2");
jLabel3.setText("n3");
jLabel5.setText("result");
jButton1.setText("Opperate");
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(15, 15, 15)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addComponent(jLabel1)
.addComponent(jLabel2)
.addComponent(jLabel3)))
.addGroup(layout.createSequentialGroup()
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jLabel5)))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addComponent(sum, javax.swing.GroupLayout.PREFERRED_SIZE, 59, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(30, 30, 30)
.addComponent(jButton1, javax.swing.GroupLayout.PREFERRED_SIZE, 79, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap())
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(n1, javax.swing.GroupLayout.PREFERRED_SIZE, 50, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(n2, javax.swing.GroupLayout.PREFERRED_SIZE, 50, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(n3, javax.swing.GroupLayout.PREFERRED_SIZE, 50, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(0, 0, Short.MAX_VALUE))))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(32, 32, 32)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(n1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jLabel1))
.addGap(10, 10, 10)
.addComponent(n2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addComponent(jLabel2))
.addGap(20, 20, 20)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(n3, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jLabel3))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(sum, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jButton1)
.addComponent(jLabel5))
.addContainerGap(38, Short.MAX_VALUE))
);
pack();
}// </editor-fold>
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
int r=Integer.parseInt(n1.getText())+Integer.parseInt(n2.getText())+Integer.parseInt(n3.getText());
sum.setText(""+r);
}
public static void main(String args[]) {
/* Set the Nimbus look and feel */
//<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
/* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
* For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html
*/
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(Frame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(Frame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(Frame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(Frame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
//</editor-fold>
/* Create and display the form */
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new Frame().setVisible(true);
}
});
}
// Variables declaration - do not modify
private javax.swing.JButton jButton1;
private javax.swing.JLabel jLabel1;
private javax.swing.JLabel jLabel2;
private javax.swing.JLabel jLabel3;
private javax.swing.JLabel jLabel5;
private javax.swing.JTextField n1;
private javax.swing.JTextField n2;
private javax.swing.JTextField n3;
private javax.swing.JTextField sum;
// End of variables declaration
}
4 个解决方案
解决方案1
4 2012-09-18 19:29:30
您正在寻找的是DocumentListener 。
向您的JTextFields n1 、 n2和n3每一个注册一个侦听器，并调用您的方法jButton1ActionPerformed来更新结果字段。
解决方案2
4 已采纳 2012-09-18 19:41:18
正如@Reimeus建议的，您需要向每个文本字段添加文档侦听器。 由于您在jButton1ActionPerformed()方法中执行添加，因此每当您的文本字段发生更改时，我都会通知侦听器调用此方法。
注意：根据评论，我更新了我的代码以仅包含一个DocumentListener并添加了一个DocumentFilter以仅接受数字输入。 我还删除了原始代码中存在的按钮来执行求和
这是您更新的代码：
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;
import javax.swing.text.AbstractDocument;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.DocumentFilter;
public class Frame extends javax.swing.JFrame {
public Frame() {
initComponents();
}
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
n1 = new javax.swing.JTextField();
n2 = new javax.swing.JTextField();
n3 = new javax.swing.JTextField();
sum = new javax.swing.JTextField();
jLabel1 = new javax.swing.JLabel();
jLabel2 = new javax.swing.JLabel();
jLabel3 = new javax.swing.JLabel();
jLabel5 = new javax.swing.JLabel();
DocumentListener documentListener = new DocumentListener() {
@Override
public void removeUpdate(DocumentEvent e) {
performSummation(null);
}
@Override
public void insertUpdate(DocumentEvent e) {
performSummation(null);
}
@Override
public void changedUpdate(DocumentEvent e) {
}
};
DocumentFilter numericFilter = new DocumentFilter(){
@Override
public void insertString(FilterBypass fb, int offset,
String string, AttributeSet attr)
throws BadLocationException {
fb.insertString(offset, string.replaceAll("[^\\d]", ""), attr);
}
@Override
public void replace(FilterBypass fb, int offset, int length,
String text, AttributeSet attrs)
throws BadLocationException {
fb.replace(offset, length, text.replaceAll("[^\\d]", ""), attrs);
}
};
((AbstractDocument) n1.getDocument()).setDocumentFilter(numericFilter);
((AbstractDocument) n2.getDocument()).setDocumentFilter(numericFilter);
((AbstractDocument) n3.getDocument()).setDocumentFilter(numericFilter);
n1.getDocument().addDocumentListener(documentListener);
n2.getDocument().addDocumentListener(documentListener);
n3.getDocument().addDocumentListener(documentListener);
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
jLabel1.setText("n1");
jLabel2.setText("n2");
jLabel3.setText("n3");
jLabel5.setText("result");
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(15, 15, 15)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addComponent(jLabel1)
.addComponent(jLabel2)
.addComponent(jLabel3)))
.addGroup(layout.createSequentialGroup()
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jLabel5)))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addComponent(sum, javax.swing.GroupLayout.PREFERRED_SIZE, 59, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(30, 30, 30)
.addContainerGap())
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(n1, javax.swing.GroupLayout.PREFERRED_SIZE, 50, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(n2, javax.swing.GroupLayout.PREFERRED_SIZE, 50, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(n3, javax.swing.GroupLayout.PREFERRED_SIZE, 50, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGap(0, 0, Short.MAX_VALUE))))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(32, 32, 32)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(n1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jLabel1))
.addGap(10, 10, 10)
.addComponent(n2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addComponent(jLabel2))
.addGap(20, 20, 20)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(n3, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jLabel3))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(sum, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jLabel5))
.addContainerGap(38, Short.MAX_VALUE))
);
pack();
}// </editor-fold>
private void performSummation(java.awt.event.ActionEvent evt) {
int total = 0;
if(n1.getText().trim().length() > 0){
try{
total += Integer.parseInt(n1.getText());
}catch(NumberFormatException nbx){
}
}
if(n2.getText().trim().length() > 0){
try{
total += Integer.parseInt(n2.getText());
}catch(NumberFormatException nbx){
}
}
if(n3.getText().trim().length() > 0){
try{
total += Integer.parseInt(n3.getText());
}catch(NumberFormatException nbx){
}
}
sum.setText(""+total);
}
public static void main(String args[]) {
/* Set the Nimbus look and feel */
//<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
/* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
* For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html
*/
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(Frame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(Frame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(Frame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(Frame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
//</editor-fold>
/* Create and display the form */
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new Frame().setVisible(true);
}
});
}
// Variables declaration - do not modify
private javax.swing.JLabel jLabel1;
private javax.swing.JLabel jLabel2;
private javax.swing.JLabel jLabel3;
private javax.swing.JLabel jLabel5;
private javax.swing.JTextField n1;
private javax.swing.JTextField n2;
private javax.swing.JTextField n3;
private javax.swing.JTextField sum;
// End of variables declaration
}
几个提示：
永远不要相信来自用户的输入。 用户可能会输入不正确的值（说一些不是 Integer 的值）。 因此，验证您的输入并检查输入是否可以被实际解析总是一个好主意。 记住这一点，我更新了你的
jButton1ActionPerformed()方法另一种选择是使用格式化文本字段
解决方案3
2 2012-09-18 20:31:03
这种替代方法使用PropertyChangeListener和FocusListener来update()使用JFormattedTextField的值的总和。
解决方案4
0
您可以使用焦点侦听器，也可以对输入JTextField使用动作侦听器
使用Java中的JTextfields将数据更新到oracle数据库中的问题
[英]Issue in updating data into oracle database using JTextfields in java
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