我想計算對數值,但空文本字段發生錯誤。如何處理空文本字段的異常?
//Libraries
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.JOptionPane;
import java.awt.Font; //For Font And Size
import java.awt.Color; //For Color Change
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
public class ChildClass extends JFrame {
private JTextField textfield1;
private JTextField textfield3;
private JTextField textfield4;
private JButton button1;
public ChildClass() {
super("Logrithm");
getContentPane().setBackground(new Color(153, 204, 153));
getContentPane().setLayout(null);
textfield1 = new JTextField();
textfield1.setBounds(62, 77, 62, 26);
getContentPane().add(textfield1);
textfield3 = new JTextField();
textfield3.setBounds(127, 224, 153, 26);
getContentPane().add(textfield3);
textfield4 = new JTextField();
textfield4.setBounds(175, 124, 62, 26);
getContentPane().add(textfield4);
button1 = new JButton();
button1.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
double number1,baseE,result;
String text1 = textfield1.getText();
String text3 = textfield4.getText();
if (text1.isEmpty() && text3.isEmpty()) {
JOptionPane.showMessageDialog(null, "Enter Values In TextField", "Invalid TextFields", JOptionPane.ERROR_MESSAGE);
}
if (text3.isEmpty()) {
number1 = Double.parseDouble(text1);
result = Math.log(number1);
textfield3.setText("" + result);
}
else if (!text3.isEmpty()) {
number1 = Double.parseDouble(text1);
baseE = Double.parseDouble(text3);
result = Math.log(number1)/Math.log(baseE);
textfield3.setText("" + result);
}
}
});
button1.setFont(new Font("Bullet", Font.PLAIN, 16));
button1.setText("Click It");
button1.setBounds(161, 172, 87, 26);
getContentPane().add(button1);
}
}
這是主要方法:
public class MainMethod {
public static void main(String[] args) {
ChildClass obj=new ChildClass();
obj.setSize(450, 400);
obj.setResizable(false);
obj.setDefaultCloseOperation(obj.EXIT_ON_CLOSE);
obj.setLocationRelativeTo(null);
obj.setVisible(true);
}
}
問題我面臨的,當我點擊空文本框將JButton。 Popup MessageDialog出現後,我點擊確定,然後:
Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: empty String
如何處理此錯誤?
將剩餘的會話邏輯包含在else if(text1.isEmpty()&& text3.isEmpty()){「 – MadProgrammer
使用JSpinner或JFormattedTextField,它們能夠執行自己的驗證 – MadProgrammer