我最近在修改摇摆计算器上的按钮大小时遇到了问题。如果你运行它，你会看到一个几乎与常规Windows计算器一样好的计算器。但我试图让它看起来像一个常规的Windows计算器完全。我已经放下了代码，我有几个问题。
顺便说一下，如果有人第一次回答图形问题，我更愿意，我相信我可以自己计算出这些功能。
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);
}
}
答案 0 :(得分：1)
回答1和2：
您需要更好地在堆栈中跟踪您的操作员，或者存储您需要的信息，直到您想要“清除”历史记录。这是一个在线制作类似程序的例子。
Java: Example - Simple Calculator
以下是您的代码中所需的一些更改的一些细节......
在processEquals()功能的第415行，您清除了opera变量。这使得第二次按下等号无效。如果你注释掉那一行，它应该会更好。
在operation(String)函数的第390行，您将获得NumberInTheDisplay()以便在操作中使用，但如果他们决定两次单击等号，则您不会保留它。您需要存储此值并使其可用于processEquals()。
通常，在进行故障排除或添加功能时，请确定当前行为，并确定所需的行为，并将差异细分为可管理的块。
还针对特定功能和行为进行一组单元测试，以便了解它何时起作用以及何时起作用。
除此之外，您需要自己调试它。祝好运。
回答3：
How to set the component size with GridLayout? Is there a better way?
回答4：
答案 1 :(得分：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简洁。感觉依赖，因此可能不适用于每个L＆amp; F.例如，如果你想让JButton有一个更大的Font，你可以这样做：
Font btnFont = UIManager.getFont("Button.font");
float fontSize = 16f;
btnFont = btnFont.deriveFont(fontSize);
UIManager.put("Button.font", btnFont);
我相信在创建任何JButton之前可能需要调用它。因此，在创建Calculator对象之前，可以在main方法中调用它，或者其他位置可以在静态初始化程序块中。