java - 修改我的java swing计算器的图形

Question

我最近在修改挥杆计算器上的按钮大小时遇到​​了问题。如果您运行它，您将看到一个计算器，它几乎与常规 Windows 计算器一样好用。但我试图让它看起来完全像一个普通的Windows计算器。我已经把代码写下来了，我有几个问题。

1. 如果按两次等于，您会发现文本上的数字将设置为零。有人可以给我一个提示来解决这个问题吗？
2. 如果您按两个连续的功能(例如加法然后乘法)，您会发现它通常执行第一个功能。它应该执行按下的第二个功能。再说一次，有人可以给我一个提示来解决这个问题吗？
3. Ggraphics:如何调整按钮的大小？我尝试调用buttons.resize()，它应该像在java API中一样工作，但由于某种原因它没有效果。
4. 如何将按钮上的文本设置为不同的颜色？

顺便说一句，我希望有人先回答图形问题，我确信我可以自己弄清楚功能。

   import java.awt.BorderLayout;
   import java.awt.Color;
   import java.awt.Container;
   import java.awt.FlowLayout;
   import java.awt.GridLayout;
   import java.awt.event.ActionEvent;
   import java.awt.event.ActionListener;
   import javax.swing.*;
   import java.awt.GridBagConstraints;
   import java.awt.Dimension;

    public class Calculator extends JFrame implements ActionListener
   {  
      JButton button1 = new JButton("1");
      JButton button2 = new JButton("2");
      JButton button3 = new JButton("3");
      JButton button4 = new JButton("4");
      JButton button5 = new JButton("5");
      JButton button6 = new JButton("6");
      JButton button7 = new JButton("7");
      JButton button8 = new JButton("8");
      JButton button9 = new JButton("9");
      JButton button0 = new JButton("0");

      JButton buttonAdd = new JButton("+");
      JButton buttonSub = new JButton("-");
      JButton buttonMult = new JButton("*");
      JButton buttonDiv = new JButton("/");
      JButton buttonEquals = new JButton("=");
      JButton buttonClear = new JButton("C");

      JButton plusOrMinus = new JButton("+/-");
      JButton decimal = new JButton(".");
      JButton squareRoot = new JButton("sqrt.");
      JButton inverse = new JButton("1/x");
      JButton mod = new JButton("%");
      JButton backSpace = new JButton("Backspace");
      JButton clearE = new JButton("CE");

      JButton memoryClear = new JButton("MC");
      JButton memoryRecall = new JButton("MR");
      JButton memoryStore = new JButton("MS");
      JButton memoryAdd = new JButton("M+");

      JPanel jBack = new JPanel();
      JLabel output = new JLabel("0");
      JPanel jSpacing = new JPanel();
      JPanel jMstr = new JPanel();
      JPanel buttonSpace = new JPanel();

      double firstNumber, memoryNumber;
      String opera = "0";
      boolean clear;

       public Calculator()
      {     
         output.setHorizontalTextPosition(JLabel.RIGHT);
         output.setBackground(Color.WHITE);
         output.setOpaque(true);

         getContentPane().add(output, BorderLayout.NORTH);

         jBack.setLayout(new GridLayout(1, 1, 2, 2));
         jBack.add(backSpace);

         jSpacing.setLayout(new GridLayout(1, 2, 2, 2));        
         jSpacing.add(clearE);
         jSpacing.add(buttonClear);

         buttonSpace.setLayout(new GridLayout(4, 5, 2, 2));

         buttonSpace.add(memoryClear);   
         buttonSpace.add(button7);
         buttonSpace.add(button8);
         buttonSpace.add(button9);
         buttonSpace.add(buttonDiv);
         buttonSpace.add(squareRoot);

         buttonSpace.add(memoryRecall);   
         buttonSpace.add(button4);
         buttonSpace.add(button5);
         buttonSpace.add(button6);
         buttonSpace.add(buttonMult);
         buttonSpace.add(inverse);

         buttonSpace.add(memoryStore);         
         buttonSpace.add(button1);
         buttonSpace.add(button2);
         buttonSpace.add(button3);
         buttonSpace.add(buttonSub);
         buttonSpace.add(mod);

         buttonSpace.add(memoryAdd);
         buttonSpace.add(button0);
         buttonSpace.add(plusOrMinus);
         buttonSpace.add(decimal);
         buttonSpace.add(buttonAdd);
         buttonSpace.add(buttonEquals);

         jMstr.setLayout(new BorderLayout());
         jMstr.add(jBack, BorderLayout.WEST);
         jMstr.add(jSpacing, BorderLayout.EAST);
         jMstr.add(buttonSpace, BorderLayout.SOUTH);

         getContentPane().add(jMstr, BorderLayout.SOUTH);

         button1.addActionListener(this);
         button2.addActionListener(this);
         button3.addActionListener(this);
         button4.addActionListener(this);
         button5.addActionListener(this);
         button6.addActionListener(this);
         button7.addActionListener(this);
         button8.addActionListener(this);
         button9.addActionListener(this);
         button0.addActionListener(this);

         buttonAdd.addActionListener(this);
         buttonSub.addActionListener(this);
         buttonMult.addActionListener(this);
         buttonDiv.addActionListener(this);
         buttonEquals.addActionListener(this);
         buttonClear.addActionListener(this);

         plusOrMinus.addActionListener(this);
         decimal.addActionListener(this);
         squareRoot.addActionListener(this);
         inverse.addActionListener(this);
         mod.addActionListener(this);
         backSpace.addActionListener(this);
         clearE.addActionListener(this);

         memoryClear.addActionListener(this);
         memoryRecall.addActionListener(this);
         memoryStore.addActionListener(this);
         memoryAdd.addActionListener(this);

         try
         {
            UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
         }

             catch(Exception e)
            {
            }       

         SwingUtilities.updateComponentTreeUI(jMstr);       
      }

       public void actionPerformed(ActionEvent e)
      {
         double result = 0;

         if(e.getSource() == buttonEquals)
         {
            processEquals();
         }

         if(e.getSource() == button0)
         {
            putDigitOnLabel(0);
         }

         if(e.getSource() == button1)
         {
            putDigitOnLabel(1);
         }

         if(e.getSource() == button2)
         {
            putDigitOnLabel(2);
         }

         if(e.getSource() == button3)
         {
            putDigitOnLabel(3);
         }

         if(e.getSource() == button4)
         {
            putDigitOnLabel(4);
         }

         if(e.getSource() == button5)
         {
            putDigitOnLabel(5);
         }

         if(e.getSource() == button6)
         {
            putDigitOnLabel(6);
         }

         if(e.getSource() == button7)
         {
            putDigitOnLabel(7);
         }

         if(e.getSource() == button8)
         {
            putDigitOnLabel(8);
         }

         if(e.getSource() == button9)
         {
            putDigitOnLabel(9);
         }

         if(e.getSource() == plusOrMinus)
         {
            changeSign();
         }

         if(e.getSource() == decimal)
         {
            addDecimalPoint();
         }

         if(e.getSource() == buttonDiv)
         {
            if(getNumberInDisplay() == 0)
            {
               output.setText("Cannot divide a number by zero.");
            }
            operation("/");
         }

         if(e.getSource() == buttonMult)
         {
            operation("*");
         }

         if(e.getSource() == buttonSub)
         {
            operation("-");
         }

         if(e.getSource() == buttonAdd)
         {
            operation("+");
         }

         if(e.getSource() == squareRoot)
         {
            if(getNumberInDisplay() < 0)
            {
               output.setText("Cannot take the square root of a negative number.");
            }

            double num = Math.sqrt(Double.parseDouble(output.getText()));
            output.setText(Double.toString(num));

         }

         if(e.getSource() == inverse)
         {
            if(getNumberInDisplay() == 0)
            {
               output.setText("Cannot take the inverse of the number zero");
            }
            double num = 1/( Double.parseDouble(output.getText()));
            output.setText(Double.toString(num));
         }

         if(e.getSource() == mod)
         {
            result = getNumberInDisplay() / 100;
            displayResult(result);
         }

         if(e.getSource() == backSpace)
         {


     setTextOnOutput(getStringOnDisplay().substring(0, getStringOnDisplay().length()-1));   


         }

         if(e.getSource() == clearE)
         {
            clearEverythingButOperation();
         }

         if(e.getSource() == buttonClear)
         {
            clearEverything();
         }  

         if(e.getSource() == memoryRecall)
         {
            displayResult(memoryNumber);
         }

         if(e.getSource() == memoryStore)
         {
            memoryNumber = getNumberInDisplay();
         }

         if(e.getSource() == memoryAdd)
         {
            memoryNumber += getNumberInDisplay();
         }   

         if(e.getSource() == memoryClear)
         {
            memoryNumber = 0;
         }                          
      } 

       public void setTextOnOutput(String s)
      {
         output.setText(s);
      }

       public String getStringOnDisplay()
      {
         return output.getText();
      }

       public void putDigitOnLabel(int digit)
      {
         if(clear == true)
         {
            output.setText("");
         }

         if(getStringOnDisplay().indexOf("0") == 0)
         {
            setTextOnOutput(getStringOnDisplay().substring(1));
         }

         output.setText(getStringOnDisplay() + digit);

         clear = false;
      }     

       public void addDecimalPoint()
      {
         if(clear == true)
         {
            setTextOnOutput("");
         }

         if(getStringOnDisplay().indexOf(".") == -1)
         {
            setTextOnOutput(new String(getStringOnDisplay() + "."));
         }
      }

       public void changeSign()
      {
         if(Double.parseDouble(output.getText()) < 0)
         {
            setTextOnOutput(getStringOnDisplay().substring(1));
         }

         if(Double.parseDouble(output.getText()) > 0)
         {
            setTextOnOutput(Double.toString(getNumberInDisplay() * -1));
         }    
      } 

       public void clearEverythingButOperation()
      {
         setTextOnOutput("0");
         clear = true;      
      }

       public void clearEverything()
      {
         setTextOnOutput("0");
         opera = "0";
         firstNumber = 0;
         clear = true;
      }

       public double getNumberInDisplay()
      {
         String stuff = output.getText();
         return Double.parseDouble(stuff);
      }

       public void operation(String s)
      {      
         double number = getNumberInDisplay();

         if(!(opera.equals("0")))
         {         
            double result = processOperator();
            displayResult(result);
            firstNumber = result;
         }

         else
         {
            firstNumber = number;
         }

         clear = true;
         opera = s;
      }

       public void processEquals()
      {
         double result;

         result = processOperator();
         displayResult(result);

         opera = "0";
      }

       public double processOperator()
      {    
         double answer = 0;
         double number = getNumberInDisplay();

         if(opera.equals("*"))
         {

            answer = firstNumber * number;
         }

         if(opera.equals("-"))
         {
            answer = firstNumber - number;
         }

         if(opera.equals("+"))
         {
            answer = firstNumber + number;
         }

         if(opera.equals("/"))
         {
            answer = firstNumber / number;
         }

         return answer;
      }

       public void displayResult(double result)
      {
         setTextOnOutput(Double.toString(result));
         firstNumber = result;
         clear = true;
      }

       public static void main(String args[])
      {
         Calculator f= new Calculator();
         f.setTitle("Windows Calculator");
         f.setSize(300, 300);
         f.pack();
         f.setVisible(true);
         f.setResizable(false);
      } 
   }

Answer 1

要更改组件的默认字体，您可以尝试使用 UIManager 方法，但您需要了解这些方法可能非常依赖于外观和感觉，因此可能不适用于每个 L&F。例如，如果您希望 JButtons 有更大的字体，您可以这样做:

Font btnFont = UIManager.getFont("Button.font");
float fontSize = 16f;
btnFont = btnFont.deriveFont(fontSize);
UIManager.put("Button.font", btnFont);

我相信这可能需要在创建任何 JButton 之前调用。因此，调用它的一个地方可以是在创建 Calculator 对象之前的 main 方法中，或者另一个地方可以是静态初始化 block 内部。