JTextArea 在单击计算按钮后显示 0
JTextArea Displays 0 after calculate button clicked
我正在为大学编写这段代码，以读取用户输入并计算费用（它是医院账单）
但是当我按下计算时 JTextArea 显示 0 作为值
我是一个新手，所以任何指导都将不胜感激
密码是：
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class HospitalChargesCalculator extends JFrame implements ActionListener{
private JLabel hospitalStayLabel;
private JLabel medicationLabel;
private JLabel surgicalFeesLabel;
private JLabel labFeesLabel;
private JLabel rehabLabel;
private JLabel totalLabel;
private JTextField hospitalStayTF;
private JTextField medicationTF;
private JTextField surgicalFeesTF;
private JTextField labFeesTF;
private JTextField rehabTF;
private JTextArea totalChargesTA;
private JButton calculateB;
private JButton exitB;
public static final int WIDTH = 500;
public static final int HEIGHT = 350;
static int totalStayCharge;
static int totalMisc;
static int totalCharges;
static int totalDays;
static int totalMedication;
static int totalSurgical;
static int totalLab;
static int totalRehab;
public HospitalChargesCalculator() {
setTitle("Hospital Charges");
Container c = getContentPane();
setSize(WIDTH, HEIGHT);
c.setLayout(null);
hospitalStayLabel = new JLabel(" Number of days spent in hospital: ",
SwingConstants.LEFT);
medicationLabel = new JLabel(" Total Medication Charges: ",
SwingConstants.LEFT);
surgicalFeesLabel = new JLabel(" Total sugical charges : ",
SwingConstants.LEFT);
labFeesLabel = new JLabel(" Total lab fees: ",
SwingConstants.LEFT);
rehabLabel = new JLabel(" Total Rehab charges: ",
SwingConstants.LEFT);
totalLabel = new JLabel(" Total Charges: ",
SwingConstants.LEFT);
calculateB = new JButton("Calculate");
calculateB.addActionListener(this);
exitB = new JButton("Exit");
exitB.addActionListener(this);
hospitalStayTF = new JTextField();
medicationTF = new JTextField();
surgicalFeesTF = new JTextField();
labFeesTF = new JTextField();
rehabTF = new JTextField();
totalChargesTA = new JTextArea();
hospitalStayLabel.setSize(250, 30);
hospitalStayTF.setSize(200, 30);
medicationLabel.setSize(200, 30);
medicationTF.setSize(200, 30);
surgicalFeesLabel.setSize(200, 30);
surgicalFeesTF.setSize(200, 30);
labFeesLabel.setSize(200, 30);
labFeesTF.setSize(200, 30);
rehabLabel.setSize(200, 30);
rehabTF.setSize(200,30);
totalLabel.setSize(200, 30);
totalChargesTA.setSize(200,30);
calculateB.setSize(100, 30);
exitB.setSize(100, 30);
hospitalStayLabel.setLocation(30, 25);
hospitalStayTF.setLocation(250, 25);
medicationLabel.setLocation(30, 60);
medicationTF.setLocation(250, 60);
surgicalFeesLabel.setLocation(30, 95);
surgicalFeesTF.setLocation(250, 95);
labFeesLabel.setLocation(30, 130);
labFeesTF.setLocation(250, 130);
rehabLabel.setLocation(30, 165);
rehabTF.setLocation(250, 165);
totalLabel.setLocation(30, 250);
totalChargesTA.setLocation(250, 250);
calculateB.setLocation(70, 205);
exitB.setLocation(300, 205);
c.add(hospitalStayLabel);
c.add(hospitalStayTF);
c.add(medicationLabel);
c.add(medicationTF);
c.add(surgicalFeesLabel);
c.add(surgicalFeesTF);
c.add(labFeesLabel);
c.add(labFeesTF);
c.add(rehabLabel);
c.add(rehabTF);
c.add(totalLabel);
c.add(totalChargesTA);
c.add(calculateB);
c.add(exitB);
hospitalStayTF.addActionListener(this);
medicationTF.addActionListener(this);
surgicalFeesTF.addActionListener(this);
labFeesTF.addActionListener(this);
rehabTF.addActionListener(this);
setDefaultCloseOperation(EXIT_ON_CLOSE);
setVisible(true);
}
public void actionPerformedGet(ActionEvent g)
{
totalDays = Integer.parseInt(hospitalStayTF.getText());
totalMedication = Integer.parseInt(medicationTF.getText());
totalSurgical = Integer.parseInt(surgicalFeesTF.getText());
totalLab = Integer.parseInt(labFeesTF.getText());
totalRehab = Integer.parseInt(rehabTF.getText());
}
public int CalcStayCharges()
{
int dailyCharge = 350;
totalStayCharge = totalDays * dailyCharge;
return totalStayCharge;
}
public int CalcMiscCharges()
{
totalMisc = (totalMedication + totalSurgical + totalLab + totalRehab);
return totalMisc;
}
public int CalcTotalCharges()
{
totalCharges = (totalStayCharge + totalMisc);
return totalCharges;
}
public void actionPerformed(ActionEvent e)
{
if (e.getActionCommand().equals("Calculate"))
{
totalChargesTA.setText(String.valueOf(totalCharges));
}
else if (e.getActionCommand().equals("Exit"))
System.exit(0);
}
public static void main(String[] args)
{
HospitalChargesCalculator hospCalc = new HospitalChargesCalculator();
}
}
如果您按下按钮，您只需执行 actionPerformed(ActionEvent e)，这只会执行 totalChargesTA.setText(String.valueOf(totalCharges));。为了获得一个值，您应该在使用 setText 方法之前使用任何计算方法。
public void actionPerformed(ActionEvent e)
{
if (e.getActionCommand().equals("Calculate"))
{
totalCharges = CalcTotalCharges();
totalChargesTA.setText(String.valueOf(totalCharges));
}
else if (e.getActionCommand().equals("Exit"))
System.exit(0);
}
您可能还需要调用其他一些方法，如果它们正在计算 CalcTotalCharges.
中使用的值
我还不能评论，所以在这里作为答案。
如前所述，您实际上并没有调用 函数 来计算您使用 totalChargesTA.setText(String.valueOf(totalCharges)); 的总费用，而是尝试直接访问您方法的变量 totalCharges CalcTotalCharges() （你应该在这里调用的方法），这是唯一可能的，因为你声明 all 你的变量为 static int 所以你甚至可以在部分您实际上不想访问它们的代码。
不要将所有变量都声明为静态，否则您会看到未调用方法的错误。想想哪些变量 需要 是静态的，并将其减少到那些。
另外，不要在 中仅声明一个 函数中的所有变量，而是在该函数中声明它们，这样您就可以避免与您的静态声明相同的错误。
-- 另外，Subin Thomas 提供的答案显示了您的代码中的主要错误，他的解决方案不会起作用，因为他混淆了一些功能，您还必须修复该功能：
public int CalcTotalCharges()
{
totalCharges = (totalStayCharge + totalMisc);
return totalCharges;
}
您遇到与以下相同类型的错误：
public int CalcTotalCharges()
{
totalCharges = (CalcStayCharges() + CalcMiscCharges());
return totalCharges;
}
编辑：实际上，从输入文本字段中检索值的方式还有另一个错误。为什么要使用 public void actionPerformedGet(ActionEvent g) 方法？
这不适用于您的 ActionListener。而是将此函数中的代码复制到您的 actionPerformed 方法。然后它就会真正起作用。为了完整起见，工作代码：
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class HospitalChargesCalculator extends JFrame implements ActionListener{
private JLabel hospitalStayLabel;
private JLabel medicationLabel;
private JLabel surgicalFeesLabel;
private JLabel labFeesLabel;
private JLabel rehabLabel;
private JLabel totalLabel;
private JTextField hospitalStayTF;
private JTextField medicationTF;
private JTextField surgicalFeesTF;
private JTextField labFeesTF;
private JTextField rehabTF;
private JTextArea totalChargesTA;
private JButton calculateB;
private JButton exitB;
public static final int WIDTH = 500;
public static final int HEIGHT = 350;
int totalDays;
int totalMedication;
int totalSurgical;
int totalLab;
int totalRehab;
public HospitalChargesCalculator() {
setTitle("Hospital Charges");
Container c = getContentPane();
setSize(WIDTH, HEIGHT);
c.setLayout(null);
hospitalStayLabel = new JLabel(" Number of days spent in hospital: ",
SwingConstants.LEFT);
medicationLabel = new JLabel(" Total Medication Charges: ",
SwingConstants.LEFT);
surgicalFeesLabel = new JLabel(" Total sugical charges : ",
SwingConstants.LEFT);
labFeesLabel = new JLabel(" Total lab fees: ",
SwingConstants.LEFT);
rehabLabel = new JLabel(" Total Rehab charges: ",
SwingConstants.LEFT);
totalLabel = new JLabel(" Total Charges: ",
SwingConstants.LEFT);
calculateB = new JButton("Calculate");
calculateB.addActionListener(this);
exitB = new JButton("Exit");
exitB.addActionListener(this);
hospitalStayTF = new JTextField();
medicationTF = new JTextField();
surgicalFeesTF = new JTextField();
labFeesTF = new JTextField();
rehabTF = new JTextField();
totalChargesTA = new JTextArea();
hospitalStayLabel.setSize(250, 30);
hospitalStayTF.setSize(200, 30);
medicationLabel.setSize(200, 30);
medicationTF.setSize(200, 30);
surgicalFeesLabel.setSize(200, 30);
surgicalFeesTF.setSize(200, 30);
labFeesLabel.setSize(200, 30);
labFeesTF.setSize(200, 30);
rehabLabel.setSize(200, 30);
rehabTF.setSize(200,30);
totalLabel.setSize(200, 30);
totalChargesTA.setSize(200,30);
calculateB.setSize(100, 30);
exitB.setSize(100, 30);
hospitalStayLabel.setLocation(30, 25);
hospitalStayTF.setLocation(250, 25);
medicationLabel.setLocation(30, 60);
medicationTF.setLocation(250, 60);
surgicalFeesLabel.setLocation(30, 95);
surgicalFeesTF.setLocation(250, 95);
labFeesLabel.setLocation(30, 130);
labFeesTF.setLocation(250, 130);
rehabLabel.setLocation(30, 165);
rehabTF.setLocation(250, 165);
totalLabel.setLocation(30, 250);
totalChargesTA.setLocation(250, 250);
calculateB.setLocation(70, 205);
exitB.setLocation(300, 205);
c.add(hospitalStayLabel);
c.add(hospitalStayTF);
c.add(medicationLabel);
c.add(medicationTF);
c.add(surgicalFeesLabel);
c.add(surgicalFeesTF);
c.add(labFeesLabel);
c.add(labFeesTF);
c.add(rehabLabel);
c.add(rehabTF);
c.add(totalLabel);
c.add(totalChargesTA);
c.add(calculateB);
c.add(exitB);
hospitalStayTF.addActionListener(this);
medicationTF.addActionListener(this);
surgicalFeesTF.addActionListener(this);
labFeesTF.addActionListener(this);
rehabTF.addActionListener(this);
setDefaultCloseOperation(EXIT_ON_CLOSE);
setVisible(true);
}
public int CalcStayCharges()
{
int dailyCharge = 350;
int totalStayCharge = totalDays * dailyCharge;
return totalStayCharge;
}
public int CalcMiscCharges()
{
int totalMisc = (totalMedication + totalSurgical + totalLab + totalRehab);
return totalMisc;
}
public int CalcTotalCharges()
{
int totalCharges = (CalcStayCharges() + CalcMiscCharges());
return totalCharges;
}
public void actionPerformed(ActionEvent e)
{
totalDays = Integer.parseInt(hospitalStayTF.getText());
totalMedication = Integer.parseInt(medicationTF.getText());
totalSurgical = Integer.parseInt(surgicalFeesTF.getText());
totalLab = Integer.parseInt(labFeesTF.getText());
totalRehab = Integer.parseInt(rehabTF.getText());
if (e.getActionCommand().equals("Calculate"))
{
totalChargesTA.setText(CalcTotalCharges()+"");
}
else if (e.getActionCommand().equals("Exit"))
System.exit(0);
}
public static void main(String[] args)
{
HospitalChargesCalculator hospCalc = new HospitalChargesCalculator();
}
}
我正在为大学编写这段代码，以读取用户输入并计算费用（它是医院账单）
但是当我按下计算时 JTextArea 显示 0 作为值
我是一个新手，所以任何指导都将不胜感激
密码是：
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class HospitalChargesCalculator extends JFrame implements ActionListener{
private JLabel hospitalStayLabel;
private JLabel medicationLabel;
private JLabel surgicalFeesLabel;
private JLabel labFeesLabel;
private JLabel rehabLabel;
private JLabel totalLabel;
private JTextField hospitalStayTF;
private JTextField medicationTF;
private JTextField surgicalFeesTF;
private JTextField labFeesTF;
private JTextField rehabTF;
private JTextArea totalChargesTA;
private JButton calculateB;
private JButton exitB;
public static final int WIDTH = 500;
public static final int HEIGHT = 350;
static int totalStayCharge;
static int totalMisc;
static int totalCharges;
static int totalDays;
static int totalMedication;
static int totalSurgical;
static int totalLab;
static int totalRehab;
public HospitalChargesCalculator() {
setTitle("Hospital Charges");
Container c = getContentPane();
setSize(WIDTH, HEIGHT);
c.setLayout(null);
hospitalStayLabel = new JLabel(" Number of days spent in hospital: ",
SwingConstants.LEFT);
medicationLabel = new JLabel(" Total Medication Charges: ",
SwingConstants.LEFT);
surgicalFeesLabel = new JLabel(" Total sugical charges : ",
SwingConstants.LEFT);
labFeesLabel = new JLabel(" Total lab fees: ",
SwingConstants.LEFT);
rehabLabel = new JLabel(" Total Rehab charges: ",
SwingConstants.LEFT);
totalLabel = new JLabel(" Total Charges: ",
SwingConstants.LEFT);
calculateB = new JButton("Calculate");
calculateB.addActionListener(this);
exitB = new JButton("Exit");
exitB.addActionListener(this);
hospitalStayTF = new JTextField();
medicationTF = new JTextField();
surgicalFeesTF = new JTextField();
labFeesTF = new JTextField();
rehabTF = new JTextField();
totalChargesTA = new JTextArea();
hospitalStayLabel.setSize(250, 30);
hospitalStayTF.setSize(200, 30);
medicationLabel.setSize(200, 30);
medicationTF.setSize(200, 30);
surgicalFeesLabel.setSize(200, 30);
surgicalFeesTF.setSize(200, 30);
labFeesLabel.setSize(200, 30);
labFeesTF.setSize(200, 30);
rehabLabel.setSize(200, 30);
rehabTF.setSize(200,30);
totalLabel.setSize(200, 30);
totalChargesTA.setSize(200,30);
calculateB.setSize(100, 30);
exitB.setSize(100, 30);
hospitalStayLabel.setLocation(30, 25);
hospitalStayTF.setLocation(250, 25);
medicationLabel.setLocation(30, 60);
medicationTF.setLocation(250, 60);
surgicalFeesLabel.setLocation(30, 95);
surgicalFeesTF.setLocation(250, 95);
labFeesLabel.setLocation(30, 130);
labFeesTF.setLocation(250, 130);
rehabLabel.setLocation(30, 165);
rehabTF.setLocation(250, 165);
totalLabel.setLocation(30, 250);
totalChargesTA.setLocation(250, 250);
calculateB.setLocation(70, 205);
exitB.setLocation(300, 205);
c.add(hospitalStayLabel);
c.add(hospitalStayTF);
c.add(medicationLabel);
c.add(medicationTF);
c.add(surgicalFeesLabel);
c.add(surgicalFeesTF);
c.add(labFeesLabel);
c.add(labFeesTF);
c.add(rehabLabel);
c.add(rehabTF);
c.add(totalLabel);
c.add(totalChargesTA);
c.add(calculateB);
c.add(exitB);
hospitalStayTF.addActionListener(this);
medicationTF.addActionListener(this);
surgicalFeesTF.addActionListener(this);
labFeesTF.addActionListener(this);
rehabTF.addActionListener(this);
setDefaultCloseOperation(EXIT_ON_CLOSE);
setVisible(true);
}
public void actionPerformedGet(ActionEvent g)
{
totalDays = Integer.parseInt(hospitalStayTF.getText());
totalMedication = Integer.parseInt(medicationTF.getText());
totalSurgical = Integer.parseInt(surgicalFeesTF.getText());
totalLab = Integer.parseInt(labFeesTF.getText());
totalRehab = Integer.parseInt(rehabTF.getText());
}
public int CalcStayCharges()
{
int dailyCharge = 350;
totalStayCharge = totalDays * dailyCharge;
return totalStayCharge;
}
public int CalcMiscCharges()
{
totalMisc = (totalMedication + totalSurgical + totalLab + totalRehab);
return totalMisc;
}
public int CalcTotalCharges()
{
totalCharges = (totalStayCharge + totalMisc);
return totalCharges;
}
public void actionPerformed(ActionEvent e)
{
if (e.getActionCommand().equals("Calculate"))
{
totalChargesTA.setText(String.valueOf(totalCharges));
}
else if (e.getActionCommand().equals("Exit"))
System.exit(0);
}
public static void main(String[] args)
{
HospitalChargesCalculator hospCalc = new HospitalChargesCalculator();
}
}
如果您按下按钮，您只需执行 actionPerformed(ActionEvent e)，这只会执行 totalChargesTA.setText(String.valueOf(totalCharges));。为了获得一个值，您应该在使用 setText 方法之前使用任何计算方法。
public void actionPerformed(ActionEvent e)
{
if (e.getActionCommand().equals("Calculate"))
{
totalCharges = CalcTotalCharges();
totalChargesTA.setText(String.valueOf(totalCharges));
}
else if (e.getActionCommand().equals("Exit"))
System.exit(0);
}
您可能还需要调用其他一些方法，如果它们正在计算 CalcTotalCharges.
我还不能评论，所以在这里作为答案。
如前所述，您实际上并没有调用 函数 来计算您使用 totalChargesTA.setText(String.valueOf(totalCharges)); 的总费用，而是尝试直接访问您方法的变量 totalCharges CalcTotalCharges() （你应该在这里调用的方法），这是唯一可能的，因为你声明 all 你的变量为 static int 所以你甚至可以在部分您实际上不想访问它们的代码。
不要将所有变量都声明为静态，否则您会看到未调用方法的错误。想想哪些变量 需要 是静态的，并将其减少到那些。
另外，不要在 中仅声明一个 函数中的所有变量，而是在该函数中声明它们，这样您就可以避免与您的静态声明相同的错误。
-- 另外，Subin Thomas 提供的答案显示了您的代码中的主要错误，他的解决方案不会起作用，因为他混淆了一些功能，您还必须修复该功能：
public int CalcTotalCharges()
{
totalCharges = (totalStayCharge + totalMisc);
return totalCharges;
}
您遇到与以下相同类型的错误：
public int CalcTotalCharges()
{
totalCharges = (CalcStayCharges() + CalcMiscCharges());
return totalCharges;
}
编辑：实际上，从输入文本字段中检索值的方式还有另一个错误。为什么要使用 public void actionPerformedGet(ActionEvent g) 方法？
这不适用于您的 ActionListener。而是将此函数中的代码复制到您的 actionPerformed 方法。然后它就会真正起作用。为了完整起见，工作代码：
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class HospitalChargesCalculator extends JFrame implements ActionListener{
private JLabel hospitalStayLabel;
private JLabel medicationLabel;
private JLabel surgicalFeesLabel;
private JLabel labFeesLabel;
private JLabel rehabLabel;
private JLabel totalLabel;
private JTextField hospitalStayTF;
private JTextField medicationTF;
private JTextField surgicalFeesTF;
private JTextField labFeesTF;
private JTextField rehabTF;
private JTextArea totalChargesTA;
private JButton calculateB;
private JButton exitB;
public static final int WIDTH = 500;
public static final int HEIGHT = 350;
int totalDays;
int totalMedication;
int totalSurgical;
int totalLab;
int totalRehab;
public HospitalChargesCalculator() {
setTitle("Hospital Charges");
Container c = getContentPane();
setSize(WIDTH, HEIGHT);
c.setLayout(null);
hospitalStayLabel = new JLabel(" Number of days spent in hospital: ",
SwingConstants.LEFT);
medicationLabel = new JLabel(" Total Medication Charges: ",
SwingConstants.LEFT);
surgicalFeesLabel = new JLabel(" Total sugical charges : ",
SwingConstants.LEFT);
labFeesLabel = new JLabel(" Total lab fees: ",
SwingConstants.LEFT);
rehabLabel = new JLabel(" Total Rehab charges: ",
SwingConstants.LEFT);
totalLabel = new JLabel(" Total Charges: ",
SwingConstants.LEFT);
calculateB = new JButton("Calculate");
calculateB.addActionListener(this);
exitB = new JButton("Exit");
exitB.addActionListener(this);
hospitalStayTF = new JTextField();
medicationTF = new JTextField();
surgicalFeesTF = new JTextField();
labFeesTF = new JTextField();
rehabTF = new JTextField();
totalChargesTA = new JTextArea();
hospitalStayLabel.setSize(250, 30);
hospitalStayTF.setSize(200, 30);
medicationLabel.setSize(200, 30);
medicationTF.setSize(200, 30);
surgicalFeesLabel.setSize(200, 30);
surgicalFeesTF.setSize(200, 30);
labFeesLabel.setSize(200, 30);
labFeesTF.setSize(200, 30);
rehabLabel.setSize(200, 30);
rehabTF.setSize(200,30);
totalLabel.setSize(200, 30);
totalChargesTA.setSize(200,30);
calculateB.setSize(100, 30);
exitB.setSize(100, 30);
hospitalStayLabel.setLocation(30, 25);
hospitalStayTF.setLocation(250, 25);
medicationLabel.setLocation(30, 60);
medicationTF.setLocation(250, 60);
surgicalFeesLabel.setLocation(30, 95);
surgicalFeesTF.setLocation(250, 95);
labFeesLabel.setLocation(30, 130);
labFeesTF.setLocation(250, 130);
rehabLabel.setLocation(30, 165);
rehabTF.setLocation(250, 165);
totalLabel.setLocation(30, 250);
totalChargesTA.setLocation(250, 250);
calculateB.setLocation(70, 205);
exitB.setLocation(300, 205);
c.add(hospitalStayLabel);
c.add(hospitalStayTF);
c.add(medicationLabel);
c.add(medicationTF);
c.add(surgicalFeesLabel);
c.add(surgicalFeesTF);
c.add(labFeesLabel);
c.add(labFeesTF);
c.add(rehabLabel);
c.add(rehabTF);
c.add(totalLabel);
c.add(totalChargesTA);
c.add(calculateB);
c.add(exitB);
hospitalStayTF.addActionListener(this);
medicationTF.addActionListener(this);
surgicalFeesTF.addActionListener(this);
labFeesTF.addActionListener(this);
rehabTF.addActionListener(this);
setDefaultCloseOperation(EXIT_ON_CLOSE);
setVisible(true);
}
public int CalcStayCharges()
{
int dailyCharge = 350;
int totalStayCharge = totalDays * dailyCharge;
return totalStayCharge;
}
public int CalcMiscCharges()
{
int totalMisc = (totalMedication + totalSurgical + totalLab + totalRehab);
return totalMisc;
}
public int CalcTotalCharges()
{
int totalCharges = (CalcStayCharges() + CalcMiscCharges());
return totalCharges;
}
public void actionPerformed(ActionEvent e)
{
totalDays = Integer.parseInt(hospitalStayTF.getText());
totalMedication = Integer.parseInt(medicationTF.getText());
totalSurgical = Integer.parseInt(surgicalFeesTF.getText());
totalLab = Integer.parseInt(labFeesTF.getText());
totalRehab = Integer.parseInt(rehabTF.getText());
if (e.getActionCommand().equals("Calculate"))
{
totalChargesTA.setText(CalcTotalCharges()+"");
}
else if (e.getActionCommand().equals("Exit"))
System.exit(0);
}
public static void main(String[] args)
{
HospitalChargesCalculator hospCalc = new HospitalChargesCalculator();
}
}