我的GUI代碼有什麼問題？

對不起，代碼量很大，但我覺得它是需要的。我想知道我的代碼有什麼問題。談到GUI界面，我是一名初學者。當我運行我的程序時，窗口彈出，當我計算出整個程序凍結時，我甚至無法弄清楚它有什麼問題。難道你們看不到任何東西，我可能做錯了我的GUI代碼有什麼問題？

package my.mortgagecalculation3; 

import java.text.NumberFormat; 
import javax.swing.JOptionPane; 
import javax.swing.JFrame; 

/** 
* 
* @author Akira 
*/ 
public class MortgageCalculation3UI extends javax.swing.JFrame { 

/** 
* Creates new form MortgageCalculation3UI 
*/ 
public MortgageCalculation3UI() { 
    initComponents(); 
} 

/** 
* This method is called from within the constructor to initialize the form. 
* WARNING: Do NOT modify this code. The content of this method is always 
* regenerated by the Form Editor. 
*/ 
@SuppressWarnings("unchecked") 
// <editor-fold defaultstate="collapsed" desc="Generated Code">       
private void initComponents() { 

    jPanel1 = new javax.swing.JPanel(); 
    javax.swing.JLabel lblMortgageCalculator = new javax.swing.JLabel(); 
    lblLoanAmount = new javax.swing.JLabel(); 
    lblInterestRate = new javax.swing.JLabel(); 
    lblNumberYears = new javax.swing.JLabel(); 
    lblMonthly = new javax.swing.JLabel(); 
    txtLoanAmount = new javax.swing.JTextField(); 
    txtInterestRate = new javax.swing.JTextField(); 
    txtNumberYears = new javax.swing.JTextField(); 
    txtMonthlyPayment = new javax.swing.JTextField(); 
    btnCalculate = new javax.swing.JButton(); 
    btnReset = new javax.swing.JButton(); 
    btnExit = new javax.swing.JButton(); 

    javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1); 
    jPanel1.setLayout(jPanel1Layout); 
    jPanel1Layout.setHorizontalGroup(
     jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
     .addGap(0, 109, Short.MAX_VALUE) 
    ); 
    jPanel1Layout.setVerticalGroup(
     jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
     .addGap(0, 114, Short.MAX_VALUE) 
    ); 

    setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE); 

    lblMortgageCalculator.setFont(new java.awt.Font("Times New Roman", 1, 18)); // NOI18N 
    lblMortgageCalculator.setHorizontalAlignment(javax.swing.SwingConstants.CENTER); 
    lblMortgageCalculator.setText("Mortgage Calculator"); 

    lblLoanAmount.setFont(new java.awt.Font("Times New Roman", 0, 14)); // NOI18N 
    lblLoanAmount.setHorizontalAlignment(javax.swing.SwingConstants.LEFT); 
    lblLoanAmount.setLabelFor(lblLoanAmount); 
    lblLoanAmount.setText("Loan Amount :"); 

    lblInterestRate.setFont(new java.awt.Font("Times New Roman", 0, 14)); // NOI18N 
    lblInterestRate.setText("Interest Rate :"); 
    lblInterestRate.setToolTipText(""); 
    lblInterestRate.setName("lblInterestRate"); // NOI18N 

    lblNumberYears.setFont(new java.awt.Font("Times New Roman", 0, 14)); // NOI18N 
    lblNumberYears.setText("Years to pay :"); 
    lblNumberYears.setToolTipText(""); 

    lblMonthly.setFont(new java.awt.Font("Times New Roman", 0, 14)); // NOI18N 
    lblMonthly.setText("Monthly Payment :"); 

    txtLoanAmount.setFont(new java.awt.Font("Times New Roman", 0, 14)); // NOI18N 
    txtLoanAmount.addActionListener(new java.awt.event.ActionListener() { 
     public void actionPerformed(java.awt.event.ActionEvent evt) { 
      txtLoanAmountActionPerformed(evt); 
     } 
    }); 

    txtInterestRate.setFont(new java.awt.Font("Times New Roman", 0, 14)); // NOI18N 

    txtNumberYears.setFont(new java.awt.Font("Times New Roman", 0, 14)); // NOI18N 

    txtMonthlyPayment.setFont(new java.awt.Font("Times New Roman", 0, 14)); // NOI18N 

    btnCalculate.setFont(new java.awt.Font("Times New Roman", 1, 12)); // NOI18N 
    btnCalculate.setText("Calculate"); 
    btnCalculate.addActionListener(new java.awt.event.ActionListener() { 
     public void actionPerformed(java.awt.event.ActionEvent evt) { 
      btnCalculateActionPerformed(evt); 
     } 
    }); 

    btnReset.setFont(new java.awt.Font("Times New Roman", 1, 12)); // NOI18N 
    btnReset.setText("Reset"); 
    btnReset.addActionListener(new java.awt.event.ActionListener() { 
     public void actionPerformed(java.awt.event.ActionEvent evt) { 
      btnResetActionPerformed(evt); 
     } 
    }); 

    btnExit.setFont(new java.awt.Font("Times New Roman", 1, 12)); // NOI18N 
    btnExit.setText("Exit"); 
    btnExit.addActionListener(new java.awt.event.ActionListener() { 
     public void actionPerformed(java.awt.event.ActionEvent evt) { 
      btnExitActionPerformed(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() 
      .addContainerGap() 
      .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
       .addComponent(lblMortgageCalculator, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE) 
       .addGroup(layout.createSequentialGroup() 
        .addGap(23, 23, 23) 
        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
         .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false) 
          .addGroup(layout.createSequentialGroup() 
           .addComponent(lblMonthly) 
           .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED) 
           .addComponent(txtMonthlyPayment)) 
          .addGroup(layout.createSequentialGroup() 
           .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING) 
            .addComponent(lblInterestRate, javax.swing.GroupLayout.PREFERRED_SIZE, 84, javax.swing.GroupLayout.PREFERRED_SIZE) 
            .addComponent(lblLoanAmount) 
            .addComponent(lblNumberYears, javax.swing.GroupLayout.PREFERRED_SIZE, 84, javax.swing.GroupLayout.PREFERRED_SIZE)) 
           .addGap(34, 34, 34) 
           .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false) 
            .addComponent(txtLoanAmount) 
            .addComponent(txtInterestRate) 
            .addComponent(txtNumberYears, javax.swing.GroupLayout.DEFAULT_SIZE, 154, Short.MAX_VALUE)))) 
         .addGroup(layout.createSequentialGroup() 
          .addComponent(btnCalculate, javax.swing.GroupLayout.PREFERRED_SIZE, 90, javax.swing.GroupLayout.PREFERRED_SIZE) 
          .addGap(18, 18, 18) 
          .addComponent(btnReset, javax.swing.GroupLayout.PREFERRED_SIZE, 90, javax.swing.GroupLayout.PREFERRED_SIZE) 
          .addGap(18, 18, 18) 
          .addComponent(btnExit, javax.swing.GroupLayout.PREFERRED_SIZE, 90, javax.swing.GroupLayout.PREFERRED_SIZE))) 
        .addGap(0, 28, Short.MAX_VALUE))) 
      .addContainerGap()) 
    ); 
    layout.setVerticalGroup(
     layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
     .addGroup(layout.createSequentialGroup() 
      .addGap(19, 19, 19) 
      .addComponent(lblMortgageCalculator, javax.swing.GroupLayout.PREFERRED_SIZE, 25, javax.swing.GroupLayout.PREFERRED_SIZE) 
      .addGap(18, 18, 18) 
      .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE) 
       .addComponent(lblLoanAmount, javax.swing.GroupLayout.PREFERRED_SIZE, 22, javax.swing.GroupLayout.PREFERRED_SIZE) 
       .addComponent(txtLoanAmount, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)) 
      .addGap(18, 18, 18) 
      .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE) 
       .addComponent(lblInterestRate, javax.swing.GroupLayout.PREFERRED_SIZE, 22, javax.swing.GroupLayout.PREFERRED_SIZE) 
       .addComponent(txtInterestRate, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)) 
      .addGap(18, 18, 18) 
      .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE) 
       .addComponent(lblNumberYears, javax.swing.GroupLayout.PREFERRED_SIZE, 22, javax.swing.GroupLayout.PREFERRED_SIZE) 
       .addComponent(txtNumberYears, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)) 
      .addGap(45, 45, 45) 
      .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE) 
       .addComponent(lblMonthly, javax.swing.GroupLayout.PREFERRED_SIZE, 22, javax.swing.GroupLayout.PREFERRED_SIZE) 
       .addComponent(txtMonthlyPayment, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)) 
      .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 50, Short.MAX_VALUE) 
      .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false) 
       .addComponent(btnCalculate, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.DEFAULT_SIZE, 38, Short.MAX_VALUE) 
       .addComponent(btnExit, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE) 
       .addComponent(btnReset, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)) 
      .addGap(27, 27, 27)) 
    ); 

    pack(); 
}// </editor-fold>       

private void btnExitActionPerformed(java.awt.event.ActionEvent evt) {           
    System.exit(0); 
}          

private void btnResetActionPerformed(java.awt.event.ActionEvent evt) {           
    txtLoanAmount.setText(""); 
    txtInterestRate.setText(""); 
    txtNumberYears.setText(""); 
}           

private void btnCalculateActionPerformed(java.awt.event.ActionEvent evt) {            

    JFrame frame = new JFrame();   
    double loanAmount = 0; 
    double interestRate = 0; 
    double numberYears = 0; 
    double months; 
    double monthlyPayment; 
    double numerator; 
    double denominator; 
    double formula; 
    String runAgain = "y"; 


    while (runAgain.equals("y")) { 
     try { 
      loanAmount = 0; 
      interestRate = 0; 
      numberYears = 0; 

    loanAmount = Double.parseDouble(txtLoanAmount.getText()); 

    interestRate = Double.parseDouble(txtInterestRate.getText()); 

    numberYears = Double.parseDouble(txtNumberYears.getText()); 

       //if the user enters a negative number print out a error message, if not, continue calculations 
if ((loanAmount <= 0) || (interestRate <= 0) || (numberYears <= 0)) { 

    JOptionPane.showMessageDialog(frame, 
      "You must enter positive numerical data!", 
      "Invalid Data!", 
       JOptionPane.ERROR_MESSAGE); 

    } else { 
     //convert the interest rate 
     interestRate = interestRate/100/12; 

     //the number of years must be converted to months 
     months = numberYears * 12; 

     //numerator of the monthly payment formula 
     numerator = (Math.pow(1 + interestRate, months)); 

     //denominator of the monthly payment formula 
     denominator = ((numerator)-1); 

     //the formula equals the numerator divided by the denominator 
     formula = (numerator/denominator); 

     //monthly payment calculation 
     monthlyPayment = (interestRate * loanAmount * formula); 

     //sytem output 
     NumberFormat defaultFormat = NumberFormat.getCurrencyInstance(); 
     defaultFormat.format(monthlyPayment); 
     txtMonthlyPayment.setText(Double.toString(monthlyPayment)); 

    } 
     } catch (NumberFormatException e) { 
      JOptionPane.showMessageDialog(frame, 
      "You must enter positive numerical data!", 
      "Invalid Data!", 
       JOptionPane.ERROR_MESSAGE); 


     } 

      }      

}            

private void txtLoanAmountActionPerformed(java.awt.event.ActionEvent evt) {            
    // TODO add your handling code here: 
}            

/** 
* @param args the command line arguments 
*/ 
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(MortgageCalculation3UI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex); 
    } catch (InstantiationException ex) { 
     java.util.logging.Logger.getLogger(MortgageCalculation3UI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex); 
    } catch (IllegalAccessException ex) { 
     java.util.logging.Logger.getLogger(MortgageCalculation3UI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex); 
    } catch (javax.swing.UnsupportedLookAndFeelException ex) { 
     java.util.logging.Logger.getLogger(MortgageCalculation3UI.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 MortgageCalculation3UI().setVisible(true); 
     } 
    }); 
} 
// Variables declaration - do not modify      
private javax.swing.JButton btnCalculate; 
private javax.swing.JButton btnExit; 
private javax.swing.JButton btnReset; 
private javax.swing.JPanel jPanel1; 
private javax.swing.JLabel lblInterestRate; 
private javax.swing.JLabel lblLoanAmount; 
private javax.swing.JLabel lblMonthly; 
private javax.swing.JLabel lblNumberYears; 
private javax.swing.JTextField txtInterestRate; 
private javax.swing.JTextField txtLoanAmount; 
private javax.swing.JTextField txtMonthlyPayment; 
private javax.swing.JTextField txtNumberYears; 
// End of variables declaration     
}

來源

2013-11-04 Akira

爲什麼有人添加所有這些額外的代碼？ – Akira

其他用戶可以編輯帖子以改進帖子，添加標籤，重新格式化，糾正語法和拼寫。這就像一個協作維基。 –

的問題是在你的btnCalculateActionPerformed(java.awt.event.ActionEvent evt)方法：

String runAgain = "y"; 

while (runAgain.equals("y")) { 
    // do stuff here 
}

的while循環條件永遠評估爲true。計算完成後，您必須將變量更改爲其他值。我認爲在這種情況下最好使用boolean而不是String。我想知道爲什麼需要這樣做：一旦計算完成，再次運行它就沒有意義了。將結果呈現給用戶。如果他想再次運行計算，他會再次按下按鈕。

請注意，您正在UI線程中運行計算，這是一件壞事：如果它們花費太長時間，應用程序將凍結。也許你可以take a look at Swing Workers。

來源

2013-11-04 16:35:05

我有這個程序之前，我不得不實施它到一個GUI，它工作得很好。實際上，老師是否希望我們這樣做。我有一些與你所說的非常相似的東西，並且他取得了分數。 – Akira

我想在讀取輸入廣告並提供結果之後，控制檯也會讀取「runAgain」。該程序詢問用戶該做什麼，再次運行或退出。計算後，您可以將「runAgain」設置爲「n」，但即使它有效，也會感覺錯誤。 –

我的GUI代碼有什麼問題？

回答

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