Question

怎样让java文本框只输入数字问题

Answer 1

java swing中利用JFormattedTextField的控件加keyReleased能实现，以下实现的只能输入数字的文本框代码：

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import java.text.ParseException;
import javax.swing.JFormattedTextField;
import javax.swing.JFrame;
import javax.swing.JPanel;

/**
*
* @author Administrator
*/
public class JFormattedText extends JFrame {

private JFormattedTextField text;

public JFormattedText() {
JPanel panel = new JPanel();
text = new JFormattedTextField(new java.text.DecimalFormat("#0"));
// text = new JFormattedTextField();
// text.setFormatterFactory(new javax.swing.text.DefaultFormatterFactory(new javax.swing.text.NumberFormatter(new java.text.DecimalFormat("#0"))));
text.setFont(new java.awt.Font("宋体", 0, 12)); // NOI18N
text.setMaximumSize(new java.awt.Dimension(50, 21));
text.setMinimumSize(new java.awt.Dimension(50, 21));
text.setPreferredSize(new java.awt.Dimension(50, 21));
//过滤输入的字符
text.addKeyListener(new java.awt.event.KeyAdapter() {
public void keyReleased(java.awt.event.KeyEvent evt) {
String old = text.getText();
JFormattedTextField.AbstractFormatter formatter = text.getFormatter();
if (!old.equals("")) {
if (formatter != null) {
String str = text.getText();
try {
long page = (Long) formatter.stringToValue(str);
text.setText(page + "");
} catch (ParseException pe) {
text.setText("1");//解析异常直接将文本框中值设置为1
}
}
}
}
});
panel.add(text);
this.add(panel);
this.setBounds(200, 100, 100, 100);
}

public static void main(String[] arg) {
new JFormattedText().setVisible(true);
}
}