Question

我需要进行温度转换。当我将一个值输入华氏度，摄氏度或开尔文时，按下计算，它将计算其他2个值。只有两个按钮，计算和清除。当我按下计算按钮时，您将如何输入一个值并让它们计算其他两个值？

 private class ButtonHandler implements ActionListener
    {
        public void actionPerformed(ActionEvent event)
        {
            //declare three constant values for absolute zero
            double A_ZERO_F =  -459.67;
            double A_ZERO_C = -273.15;
            double A_ZERO_K = 0.0;

            // read the data from any of the fields as String types
            //We use the JTextField method getText() to do the read
            String fahrString = fahrFld.getText();
            String celsString = celsFld.getText();
            String kelvString = kelvFld.getText();

            //convert the Strings into double
            double fahrVal = Double.parseDouble(fahrFldg);
            double celsVal = Double.parseDouble(celsFld);
            double kelvVal = Double.parseDouble(kelvFld);

            ///need a value to hold the input
            double input = 0.0;     

            //the input entered now needs to be calculated

            if(event.equals(fahrString))
            {
                //fahrenheit to kelvin
                fahrVal = ((input-32.0)/1.8) + 273.15;
                kelvField.setText("" + fahrValue);
            }
            else if(event.equals(fahrString))
            {
                //fahrenheit to celsius
                celsVal = (5.0/9.0) * (input-32.0);
                celsField.setText(""+ celsVal);
            }
            else if(event.equals(celsString))
            {
                //celsius to fahrenheit
                fahrVal = ((9.0/5.0)*input) + 32.0;
                fahrField.setText(""+ fahrVal);
            }
            else if(event.equals(celsString))
            {
                //celsius to kelvin
                kelvVal = input + 273.15;
                celsField.setText(""+ kelvVal);
            }
            else if(event.equals(kelvString))
            {
                //kelvin to fahrenheit
                fahrVal = ((input - 273) * 1.8 ) + 32.0;
                celsField.setText("" + fahrVal);
            }
            else if (event.equals(kelvFld))
            {
                //kelvin to celsius
                celsVal = input - 273.15;
                celsField.setText(Double.toString(celsVal));
                }


            //clears all conversions when clear button is pressed
            if (event.getSource() == clearButton){
            celsFld.setText("");
            kelvFld.setText("");
            fahrFld.setText("");}

Answer 1

您的解决方案很少。

解决方案1 

你可以在某处记住你的旧价值观。在此之后 - 在您的按钮处理程序中，您可以将新值与旧值进行比较。

然而，按钮这样的计算器不是最好的主意。

解决方案2（在我看来 - 更好）

您可以编写事件，当您更改文本并在该事件处理程序中计算新值时，该事件将触发文本框。我不是Java专家，我不能提供代码示例。

Answer 2

您的情况有两个主要问题。

首先：

if(event.equals(fahrString))
{
    // some code
}
else if(event.equals(fahrString))
{
    // this will be never be executed, because if the condition
    // were true, then the if block would be executed and this skipped
}
// the same for all of your other conditions.

第二

if(event.equals(fahrString)) {

始终为false，因为event是ActionEvent而fahrString是String。

Answer 3

你可以尝试这样的事情。基本上，每次编辑其中一个字段时，MyKeyAdapter都会运行并保存已编辑的实例。接下来，检查编辑了哪个字段并激活计算。 clearButton应该可以在单独的监听器中处理，因为在这种情况下不需要计算温度。希望你能得到这个想法，并且你可以继续前进。

private void initStuff () {
    calculateButton.addActionListener(new ButtonActionEvent());
    clearButton.addActionListener(new ButtonActionEvent());
    fahrFld.addKeyListener(new MyKeyAdapter());
    celsFld.addKeyListener(new MyKeyAdapter());
    kelvFld.addKeyListener(new MyKeyAdapter());
}

private JTextField lastModified;

private class MyKeyAdapter extends KeyAdapter {
    @Override
    public void keyTyped(KeyEvent e) {
        lastModified = (JTextField)e.getSource();
    }
}

private class ButtonActionEvent implements ActionListener
{
    public void actionPerformed(ActionEvent event)
    {
        //declare three constant values for absolute zero
        double A_ZERO_F =  -459.67;
        double A_ZERO_C = -273.15;
        double A_ZERO_K = 0.0;

        if(lastModified == fahrFld)
        {
            double input = Double.parseDouble(fahrFld.getText());

            //fahrenheit to kelvin
            double kelvVal = ((input-32.0)/1.8) + 273.15;
            kelvFld.setText("" + kelvVal);

            //fahrenheit to celsius
            double celsVal = (5.0/9.0) * (input-32.0);
            celsFld.setText(""+ celsVal);
        }
        else if(lastModified == celsFld)
        {
            double input = Double.parseDouble(celsFld.getText());

            //celsius to fahrenheit
            double fahrVal = ((9.0/5.0)*input) + 32.0;
            fahrFld.setText(""+ fahrVal);

            //celsius to kelvin
            double kelvVal = input + 273.15;
            kelvFld.setText(""+ kelvVal);
        }
        else if(lastModified == kelvFld)
        {
            double input = Double.parseDouble(kelvFld.getText());

            //kelvin to fahrenheit
            double fahrVal = ((input - 273) * 1.8 ) + 32.0;
            fahrFld.setText("" + fahrVal);

            //kelvin to celsius
            double celsVal = input - 273.15;
            celsFld.setText(Double.toString(celsVal));
        } else {
            return;
        }

        //clears all conversions when clear button is pressed
        if (event.getSource() == clearButton){
            celsFld.setText("");
            kelvFld.setText("");
            fahrFld.setText("");
        }
    }
}

if语句和输入来计算温度

3 个答案: