Question

现在，在将此标记为重复之前 - 请听我说。我已经看过其他两个相似的问题。

由于这是一个GUI Java程序，因用户而异，在我的具体情况下，我只是尝试将华氏温度转换为摄氏温度而绝对没有其他功能。

这是我的代码：

package my.tempconvert;

public class TempConvertUI extends javax.swing.JFrame 
{
    public TempConvertUI() 
    {
        initComponents();
    }
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        jLabel1 = new javax.swing.JLabel();
        Farenheit = new javax.swing.JTextField();
        jLabel2 = new javax.swing.JLabel();
        Celsius = new javax.swing.JTextField();
        CalcButton = new javax.swing.JButton();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        jLabel1.setText("Farenheit");

        Farenheit.setText("Insert Farenheit Value");
        Farenheit.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                FarenheitActionPerformed(evt);
            }
        });

        jLabel2.setText("Celsius");

        Celsius.setText("Celsius Will Appear Here");

        CalcButton.setText("Calculate");
        CalcButton.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                CalcButtonActionPerformed(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()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                    .addComponent(jLabel2, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                    .addComponent(jLabel1, javax.swing.GroupLayout.DEFAULT_SIZE, 64, Short.MAX_VALUE))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                    .addComponent(Farenheit)
                    .addComponent(Celsius, javax.swing.GroupLayout.DEFAULT_SIZE, 149, Short.MAX_VALUE))
                .addGap(0, 183, Short.MAX_VALUE))
            .addGroup(layout.createSequentialGroup()
                .addGap(33, 33, 33)
                .addComponent(CalcButton, javax.swing.GroupLayout.PREFERRED_SIZE, 125, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING, false)
                    .addComponent(Farenheit, javax.swing.GroupLayout.DEFAULT_SIZE, 30, Short.MAX_VALUE)
                    .addComponent(jLabel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                    .addComponent(jLabel2, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                    .addComponent(Celsius, javax.swing.GroupLayout.DEFAULT_SIZE, 30, Short.MAX_VALUE))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(CalcButton)
                .addGap(0, 205, Short.MAX_VALUE))
        );

        pack();
    }// </editor-fold>                        
    private void FarenheitActionPerformed(java.awt.event.ActionEvent evt) {                                          

    }                                         

    private void CalcButtonActionPerformed(java.awt.event.ActionEvent evt) {                                           
         float num1, result;

    num1 = Float.parseFloat(Farenheit.getText());

    result = (((float) 5/9) * (num1 - 32));

    Celsius.setText(String.valueOf(result));
    }                                          

    public static void main(String args[]) 
    {
        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(TempConvertUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(TempConvertUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(TempConvertUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(TempConvertUI.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 TempConvertUI().setVisible(true);
            }
        });
    }

    // Variables declaration - do not modify                     
    private javax.swing.JButton CalcButton;
    private javax.swing.JTextField Celsius;
    private javax.swing.JTextField Farenheit;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    // End of variables declaration                   
}

没有语法错误 - 只有一个输出错误：

：摄氏度始终输出为0.0或-0.0 - 已解决 -

显然我的代码有问题，我需要帮助才能搞清楚这是什么。

如果有人认为我的问题不明确或者我没有遵循发布问题的指导原则，我会很乐意将这些批评考虑在内，我们都可以继续前进。

Answer 1

因为(5/9)的结果被评估为整数，所以它的值为零，因为它只取点的左边的值（例如0.0557 - > 0），你应该把它变成浮动，如下：

num1 = Float.parseFloat(Farenheit.getText());

result = (((float) 5/9) * (num1 - 32));

Celsius.setText(String.valueOf(result));

Answer 2

result = ((5/9) * (num1 - 32));

通常的整数截断问题。也是多余的括号。

result = 5*(num1-32)/9.0;

Answer 3

将5/9转换为Float，否则将其评估为整数并自动设置为0.

Java GUI - 华氏度到摄氏度

3 个答案: