英文:
Calculator Coding Errors. Please correct it
问题
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JTextField;
import java.awt.BorderLayout;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import java.awt.Font;
import javax.swing.SwingConstants;
public class FIRSTCALC {
private JFrame frame;
private JTextField txtfield1;
private JTextField txtfield2;
private JTextField textfieldans;
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
FIRSTCALC window = new FIRSTCALC();
window.frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
public FIRSTCALC() {
initialize();
}
private void initialize() {
frame = new JFrame();
frame.setBounds(100, 100, 450, 300);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().setLayout(null);
txtfield1 = new JTextField();
txtfield1.setHorizontalAlignment(SwingConstants.LEFT);
txtfield1.setText("ENTER NUMBER 1 : ");
txtfield1.setBounds(28, 11, 178, 68);
frame.getContentPane().add(txtfield1);
txtfield1.setColumns(10);
txtfield2 = new JTextField();
txtfield2.setHorizontalAlignment(SwingConstants.LEFT);
txtfield2.setText("ENTER NUMBER 2 : ");
txtfield2.setBounds(228, 11, 175, 68);
frame.getContentPane().add(txtfield2);
txtfield2.setColumns(10);
JButton btnNewButton = new JButton("ADD");
btnNewButton.setToolTipText("TO ADD NUMBERS");
btnNewButton.setFont(new Font("Sitka Text", Font.BOLD, 16));
btnNewButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
int num1, num2, sum;
try {
num1 = Integer.parseInt(txtfield1.getText());
num2 = Integer.parseInt(txtfield2.getText());
sum = num1 + num2;
textfieldans.setText(Integer.toString(sum));
} catch (Exception e1) {
JOptionPane.showMessageDialog(null, "ENTER VALID NUMBER");
}
}
});
btnNewButton.setBounds(61, 121, 120, 42);
frame.getContentPane().add(btnNewButton);
JButton btnNewButton_1 = new JButton("SUBTRACT");
btnNewButton_1.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
int num1, num2, sum;
try {
num1 = Integer.parseInt(txtfield1.getText());
num2 = Integer.parseInt(txtfield2.getText());
sum = num1 - num2;
textfieldans.setText(Integer.toString(sum));
} catch (Exception e1) {
JOptionPane.showMessageDialog(null, "ENTER VALID NUMBER");
}
}
});
btnNewButton_1.setToolTipText("TO SUBTRACT NUMBERS");
btnNewButton_1.setFont(new Font("Sitka Text", Font.BOLD, 16));
btnNewButton_1.setBounds(251, 121, 128, 42);
frame.getContentPane().add(btnNewButton_1);
JLabel lblNewLabel = new JLabel("THE ANSWER IS :");
lblNewLabel.setHorizontalAlignment(SwingConstants.CENTER);
lblNewLabel.setFont(new Font("Sitka Text", Font.BOLD, 18));
lblNewLabel.setBounds(28, 192, 193, 58);
frame.getContentPane().add(lblNewLabel);
textfieldans = new JTextField();
textfieldans.setBounds(251, 196, 109, 48);
frame.getContentPane().add(textfieldans);
textfieldans.setColumns(10);
}
}
英文:
I have tried to code a simple calculator using GUI in java but got stuck with this code and repeatedly getting a message of 'ENTER VALID NUMBERS' .I'm open to suggestions. Suggest the possible corrections in my code.I think I have wrongly used the try and check the exception feature of the java.
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JTextField;
import java.awt.BorderLayout;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import java.awt.Font;
import javax.swing.SwingConstants;
public class FIRSTCALC {
private JFrame frame;
private JTextField txtfield1;
private JTextField txtfield2;
private JTextField textfieldans;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
FIRSTCALC window = new FIRSTCALC();
window.frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the application.
*/
public FIRSTCALC() {
initialize();
}
/**
* Initialize the contents of the frame.
*/
private void initialize() {
frame = new JFrame();
frame.setBounds(100, 100, 450, 300);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().setLayout(null);
txtfield1 = new JTextField();
txtfield1.setHorizontalAlignment(SwingConstants.LEFT);
txtfield1.setText("ENTER NUMBER 1 : ");
txtfield1.setBounds(28, 11, 178, 68);
frame.getContentPane().add(txtfield1);
txtfield1.setColumns(10);
txtfield2 = new JTextField();
txtfield2.setHorizontalAlignment(SwingConstants.LEFT);
txtfield2.setText("ENTER NUMBER 2 : ");
txtfield2.setBounds(228, 11, 175, 68);
frame.getContentPane().add(txtfield2);
txtfield2.setColumns(10);
JButton btnNewButton = new JButton("ADD");
btnNewButton.setToolTipText("TO ADD NUMBERS");
btnNewButton.setFont(new Font("Sitka Text", Font.BOLD, 16));
btnNewButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
int num1,num2,sum;
try
{
num1=Integer.parseInt(txtfield1.getText());
num2=Integer.parseInt(txtfield2.getText());
sum=num1+num2;
textfieldans.setText(Integer.toString(sum));
}
catch(Exception e1)
{
JOptionPane.showMessageDialog(null, "ENTER VALID NUMBER");
}
}
});
btnNewButton.setBounds(61, 121, 120, 42);
frame.getContentPane().add(btnNewButton);
JButton btnNewButton_1 = new JButton("SUBTRACT");
btnNewButton_1.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
int num1,num2,sum;
try
{
num1=Integer.parseInt(txtfield1.getText());
num2=Integer.parseInt(txtfield2.getText());
sum=num1-num2;
textfieldans.setText(Integer.toString(sum));
}
catch(Exception e1)
{
JOptionPane.showMessageDialog(null, "ENTER VALID NUMBER");
}
}
});
btnNewButton_1.setToolTipText("TO SUBTRACT NUMBERS");
btnNewButton_1.setFont(new Font("Sitka Text", Font.BOLD, 16));
btnNewButton_1.setBounds(251, 121, 128, 42);
frame.getContentPane().add(btnNewButton_1);
JLabel lblNewLabel = new JLabel("THE ANSWER IS :");
lblNewLabel.setHorizontalAlignment(SwingConstants.CENTER);
lblNewLabel.setFont(new Font("Sitka Text", Font.BOLD, 18));
lblNewLabel.setBounds(28, 192, 193, 58);
frame.getContentPane().add(lblNewLabel);
textfieldans = new JTextField();
textfieldans.setBounds(251, 196, 109, 48);
frame.getContentPane().add(textfieldans);
textfieldans.setColumns(10);
}
}
答案1
得分: 0
以下是您提供的代码的翻译部分：
你明显出现了异常，因为你正在将输入的数字附加或添加到一个JTextField中已包含的文本中。这将在尝试使用Integer.parseInt()方法将JTextField中包含的字符串解析为整数值时生成**NumberFormatException**。如果提供的内容不是数字数字，则会抛出此异常。你只是使异常显示一个消息框，指示用户“输入有效的数字”。
如果你想保留文本字段组件中的文本，则可以应用一个焦点监听器来突出显示组件中当前的文本，这样当用户输入数字时，它会被覆盖。通常这个预设文本是浅灰色的。以下是一个示例：
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JTextField;
import javax.swing.SwingConstants;
public class FIRSTCALC {
private JFrame frame;
private JTextField txtfield1;
private JTextField txtfield2;
private JTextField textfieldans;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
FIRSTCALC window = new FIRSTCALC();
window.frame.setVisible(true);
}
catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the application.
*/
public FIRSTCALC() {
initialize();
}
/**
* Initialize the contents of the frame.
*/
private void initialize() {
frame = new JFrame();
frame.setAlwaysOnTop(true);
frame.setBounds(100, 100, 450, 300);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().setLayout(null);
txtfield1 = new JTextField("输入第一个数字");
txtfield1.setForeground(Color.lightGray);
// 为txtfield1添加焦点监听器
txtfield1.addFocusListener(new FocusListener() {
@Override
public void focusGained(FocusEvent e) {
txtfield1.selectAll();
}
@Override
public void focusLost(FocusEvent e) {
txtfield1.setForeground(Color.black);
}
});
txtfield1.setHorizontalAlignment(SwingConstants.CENTER);
txtfield1.setBounds(28, 11, 178, 68);
txtfield1.setColumns(10);
frame.getContentPane().add(txtfield1);
// ...（以下部分内容类似，省略）
frame.setLocationRelativeTo(null);
}
}
请注意，我只翻译了您提供的代码部分，没有包括注释部分。如果您有更多内容需要翻译或其他问题，请随时提问。
英文:
You are obviously getting an exception because you are appending or adding the entered number to the text already contained within one of the JTextFields. This would generate a NumberFormatException when trying to parse the string contained within JTextField to a Integer value with the Integer.parseInt() method. If anything other than numerical digits are supplied then this exception would be thrown. You're just making the exception display a Message Box indicating to the User to "ENTER VALID NUMBER".
If you want to keep the text within you text field components then apply a Focus Listener to highlight the text currently in the component so that it gets overwritten when the User enters a number. Generally this pre-text is in a lighter gray color. Here is an example:
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JTextField;
import javax.swing.SwingConstants;
public class FIRSTCALC {
private JFrame frame;
private JTextField txtfield1;
private JTextField txtfield2;
private JTextField textfieldans;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
FIRSTCALC window = new FIRSTCALC();
window.frame.setVisible(true);
}
catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the application.
*/
public FIRSTCALC() {
initialize();
}
/**
* Initialize the contents of the frame.
*/
private void initialize() {
frame = new JFrame();
frame.setAlwaysOnTop(true);
frame.setBounds(100, 100, 450, 300);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().setLayout(null);
txtfield1 = new JTextField("Enter First Number");
txtfield1.setForeground(Color.lightGray);
// Add a Focus Listener to txtfield1
txtfield1.addFocusListener(new FocusListener() {
@Override
public void focusGained(FocusEvent e) {
txtfield1.selectAll();
}
@Override
public void focusLost(FocusEvent e) {
txtfield1.setForeground(Color.black);
}
});
txtfield1.setHorizontalAlignment(SwingConstants.CENTER);
txtfield1.setBounds(28, 11, 178, 68);
txtfield1.setColumns(10);
frame.getContentPane().add(txtfield1);
txtfield2 = new JTextField("Enter Second Number");
txtfield2.setForeground(Color.lightGray);
// Add a Focus Listener to txtfield2
txtfield2.addFocusListener(new FocusListener() {
@Override
public void focusGained(FocusEvent e) {
txtfield2.selectAll();
}
@Override
public void focusLost(FocusEvent e) {
txtfield2.setForeground(Color.black);
}
});
txtfield2.setHorizontalAlignment(SwingConstants.CENTER);
txtfield2.setBounds(228, 11, 175, 68);
txtfield2.setColumns(10);
frame.getContentPane().add(txtfield2);
JButton btnNewButton = new JButton("ADD");
btnNewButton.setToolTipText("TO ADD NUMBERS");
btnNewButton.setFont(new Font("Sitka Text", Font.BOLD, 16));
btnNewButton.addActionListener(new ActionListener(){
@Override
public void actionPerformed(ActionEvent e) {
int num1, num2, sum;
try {
num1 = Integer.parseInt(txtfield1.getText());
num2 = Integer.parseInt(txtfield2.getText());
sum = num1 + num2;
textfieldans.setText(Integer.toString(sum));
}
catch (NumberFormatException ex) {
JOptionPane.showMessageDialog(frame, "<html><center>The following formula:<br><br>"
+ "<font size='4' color=red>" + txtfield1.getText() +
"</font> + <font size='4' color=red>"+ txtfield2.getText() +
"</font><br><br>contains invalid digits!</center></html>");
}
}
});
btnNewButton.setBounds(61, 121, 120, 42);
frame.getContentPane().add(btnNewButton);
JButton btnNewButton_1 = new JButton("SUBTRACT");
btnNewButton_1.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
int num1, num2, sum;
try {
num1 = Integer.parseInt(txtfield1.getText());
num2 = Integer.parseInt(txtfield2.getText());
sum = num1 - num2;
textfieldans.setText(Integer.toString(sum));
}
catch (NumberFormatException ex) {
JOptionPane.showMessageDialog(frame, "<html><center>The following formula:<br><br>"
+ "<font size='4' color=red>" + txtfield1.getText() +
"</font> - <font size='4' color=red>"+ txtfield2.getText() +
"</font><br><br>contains invalid digits!</center></html>");
}
}
});
btnNewButton_1.setToolTipText("TO SUBTRACT NUMBERS");
btnNewButton_1.setFont(new Font("Sitka Text", Font.BOLD, 16));
btnNewButton_1.setBounds(251, 121, 128, 42);
frame.getContentPane().add(btnNewButton_1);
JLabel lblNewLabel = new JLabel("THE ANSWER IS :");
lblNewLabel.setHorizontalAlignment(SwingConstants.CENTER);
lblNewLabel.setFont(new Font("Sitka Text", Font.BOLD, 18));
lblNewLabel.setBounds(28, 192, 193, 58);
frame.getContentPane().add(lblNewLabel);
textfieldans = new JTextField();
textfieldans.setHorizontalAlignment(SwingConstants.CENTER);
textfieldans.setBounds(251, 196, 109, 48);
textfieldans.setColumns(10);
frame.getContentPane().add(textfieldans);
frame.setLocationRelativeTo(null);
}
}
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