java - 为我的计算器小程序创建一个类

Question

好的，这是我开始使用的计算器的代码。

import java.awt.*;
import java.applet.*;

public class Calculator extends Applet
{

    private Label calculatorL; //Sets the label
    private boolean firstDigit = true; //Sets Boolean firstDigit to be true
    private float savedValue = 0.0f;//Sets saved value to 0
    private String operator = "="; //Sets Default operator

    public void init ()
    {
        setLayout (new BorderLayout()); //Sets the layout
        add ("North", calculatorL = new Label ("0", Label.RIGHT));
        Panel calculatorPanel = new Panel(); //Adding a panel for the buttons
        calculatorPanel.setLayout (new GridLayout (4, 4)); //Adding a 4 * 4 grid for the layout of the buttons
        calculatorPanel.setBackground(Color.CYAN);
        calculatorPanel.setForeground(Color.BLUE);
        addButtons (calculatorPanel, "123-");
        addButtons (calculatorPanel, "456*");
        addButtons (calculatorPanel, "789/");
        addButtons (calculatorPanel, ".0=+");
        add("Center", calculatorPanel);
    }

    public boolean action (Event event, Object inputobject)
    {
        if (event.target instanceof Button)
        {
            String inputstring = (String)inputobject;
            if ("0123456789.".indexOf (inputstring) != -1)
            {
                if (firstDigit)
                {
                    firstDigit = false;
                    calculatorL.setText (inputstring);
                }
                else
                {
                    calculatorL.setText(calculatorL.getText() + inputstring);
                }
            }  
            else
            {
                if(!firstDigit)
                {
                    solve(calculatorL.getText());
                    firstDigit = true;
                }
                operator = inputstring;
            }
            return true;
        }
        return false;
    }

    public void solve (String valueToBeComputed)
    {
        float sValue = new Float (valueToBeComputed).floatValue();
        char c = operator.charAt (0);
        switch (c)
        {
            case '=': savedValue = sValue;
                break;
            case '+': savedValue += sValue;
                break;
            case '-': savedValue -= sValue;
                break;
            case '*': savedValue *= sValue;
                break;
            case '/': savedValue /= sValue;
                break;
        }
        calculatorL.setText (Float.toString(savedValue));
    }

    public void addButtons (Panel panel, String labels)
    {
        int count = labels.length();
        for (int i = 0; i<count; i ++)
        {
            panel.add (new Button (labels.substring(i,i+1)));
        }
    }
}

我想做的是将我的求解器代码转移到它自己的单独的类中。

这就是我目前所拥有的

import java.awt.*;

public class Solver
{

    private String operator = "="; //Sets Default operator
    private float savedValue = 0.0f;//Sets saved value to 0

    public void solve (String valueToBeComputed)
    {
        float sValue = new Float (valueToBeComputed).floatValue();
        char c = operator.charAt (0);
        switch (c)
        {
            case '=': savedValue = sValue;
                break;
            case '+': savedValue += sValue;
                break;
            case '-': savedValue -= sValue;
                break;
            case '*': savedValue *= sValue;
                break;
            case '/': savedValue /= sValue;
                break;
        }
        calculatorL.setText (Float.toString(savedValue));
    }
}

对于使用/创建我自己的自定义类确实很陌生。可以使用一些帮助来传输和设置求解器类。

Answer 1

移动代码有时称为重构...

您可以在新类中将 solve 方法设置为静态，然后像这样调用它

Solver.solve(calculatorL.getText());

或者使用

实例化一个 Solve 对象

Solve mySolve = new Solve();

然后调用该对象的方法:

mySolve.solve(calculatorL.getText());

最后，要返回计算值，您应该将方法类型从 void 更改为 String 或 float，然后将其传递给 calculatorL.setText().