Java几何计算器案例代码

[scode type="yellow"]成果截图[/scode]

![](https://jrboy.cn/usr/uploads/2019/06/2019060715114862-300x200.png)![](https://jrboy.cn/usr/uploads/2019/06/2019060715120368-300x200.png)

[scode type="green"]代码展示[/scode]

###### 1，程序主窗体代码（CalculatorWindow.java）

```
import java.awt.BorderLayout;
import java.awt.CardLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;

import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;

public class CalculatorWindow extends JFrame implements ActionListener,ItemListener {

CardLayout mycard;
	JPanel controPanel,pCenter;
	JComboBox chooseList;
	JMenuBar menuBar;
	JMenu menu;
	JMenuItem mainWindow,exit;

public CalculatorWindow(){
		setTitle("常见几何图形计算器");

menuBar = new JMenuBar();
		menu = new JMenu("操作");
		mainWindow = new JMenuItem("主界面");
		mainWindow.addActionListener(this);
		exit = new JMenuItem("退出");
		exit.addActionListener(this);
		menu.add(mainWindow);
		menu.add(exit);
		menuBar.add(menu);
		setJMenuBar(menuBar);

mycard = new CardLayout();
		pCenter = new JPanel();
		pCenter.setLayout(mycard);
		add(pCenter,"Center");

controPanel = new JPanel();
		controPanel.setLayout(new BorderLayout());

chooseList = new JComboBox();
		chooseList.addItem("请点击下拉列表选择");
		chooseList.addItem("矩形的基本计算");
		chooseList.addItem("圆的基本计算");
		chooseList.addItem("三角形的基本计算");
		chooseList.addItem("圆柱的基本计算");
		chooseList.addItemListener(this);

ImageIcon icon = new ImageIcon(图片地址);
		JButton imageButton = new JButton(icon);

controPanel.add(imageButton,"Center");
		controPanel.add(chooseList,"North");

pCenter.add("0",controPanel);
		pCenter.add("1",new RectanglePanel());
		pCenter.add("2",new CirclePanel());
		pCenter.add("3",new TrianglePanel());
		pCenter.add("4",new CylinderPanel());

setBounds(100, 100, 700, 300);
		setResizable(false);
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		setVisible(true);

}

public void itemStateChanged(ItemEvent e) {
		int index = chooseList.getSelectedIndex();
		String choice = String.valueOf(index);
		mycard.show(pCenter, choice);

}

public void actionPerformed(ActionEvent e) {
		if (e.getSource() == mainWindow) {
			mycard.first(pCenter);
			chooseList.setSelectedIndex(0);
		}
		else if (e.getSource() == exit) {
			System.exit(0);
		}
	}

public static void main(String[] args) {
		new CalculatorWindow();
	}

}
```

###### 2，BoxPanel.java和AbstractPanel.java的实现

```
//代码（BoxPanel.java）

import java.awt.Font;

import javax.swing.Box;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class BoxPanel extends JPanel{
	JTextField text;

public BoxPanel(String s,int n) {

Box box = Box.createHorizontalBox();
		box.add(new JLabel(s));
		text = new JTextField(" ",n);

text.setHorizontalAlignment(JTextField.RIGHT);

text.setFont(new Font("Arial",Font.BOLD,15));
		box.add(text);
		add(box);

}
	public JTextField getJTextField() {
		return text;
	}
}

//代码（AbstractPanel.java）

import javax.swing.JPanel;
import javax.swing.JTextField;

public abstract class AbstractPanel extends JPanel {
	public abstract JTextField getInputTextField();
}
```

###### 3，矩形计算器的实现（RectanglePanel.java）

```
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;

import javax.swing.Box;
import javax.swing.JButton;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class RectanglePanel extends AbstractPanel implements ActionListener,FocusListener{

JButton resultButton,clearButton;
	JPanel leftPanel,rightPanel,buttonPanel;
	JTextField widthTextField,heightTextField;
	JTextField lengthTextField,areaTextField,inputTextField;
	BoxPanel bpWidth,bpHeight,bpLength,bpArea;

public RectanglePanel() {
		setLayout(new GridLayout(1,2));
		rightPanel = new KeyJPanel(this);
		leftPanel = new JPanel();

Box box = Box.createVerticalBox();
		bpWidth = new BoxPanel("请输入矩形的宽", 10);
		widthTextField = bpWidth.getJTextField();

widthTextField.addFocusListener(this);
		bpHeight = new BoxPanel("请输入矩形的高",10);
		heightTextField = bpHeight.getJTextField();
		heightTextField.addFocusListener(this);
		buttonPanel = new JPanel();
		resultButton = new JButton("计算结果");

resultButton.addActionListener(this);
		clearButton = new JButton("清空");
		clearButton.addActionListener(this);
		buttonPanel.add(resultButton);
		buttonPanel.add(clearButton);
		bpLength = new BoxPanel("矩形的周长：", 20);
		lengthTextField = bpLength.getJTextField();
		bpArea = new BoxPanel("矩形的面积：",20);
		this.areaTextField = this.bpArea.getJTextField();

box.add(bpWidth);
		box.add(bpHeight);
		box.add(buttonPanel);
		box.add(bpLength);
		box.add(bpArea);
		leftPanel.add(box);

add(leftPanel);
		add(rightPanel);
	}

public void actionPerformed(ActionEvent e) {

if (e.getSource() == resultButton) {
			try {
				double width = Double.parseDouble(widthTextField.getText());
				double height = Double.parseDouble(heightTextField.getText());
				lengthTextField.setText(""+2*(width + height));
				areaTextField.setText(""+width*height);
			} catch (NumberFormatException e1) {

JOptionPane.showMessageDialog(this, "请输入数字：","警告对话框",JOptionPane.WARNING_MESSAGE);
			}
		}

else if (e.getSource() == clearButton) {
			widthTextField.setText(" ");
			heightTextField.setText(" ");
		}
	}

public void focusGained(FocusEvent e) {
		inputTextField = (JTextField)e.getSource();
	}

public void focusLost(FocusEvent e) {}

public JTextField getInputTextField() {
		return inputTextField;
	}

}
```

###### 4，圆计算器的实现（CirclePanel.java）

```
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;

import javax.swing.Box;
import javax.swing.JButton;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class CirclePanel extends AbstractPanel implements ActionListener,FocusListener{

JButton resultButton,clearButton;
	JPanel leftPanel,rightPanel,buttonPanel;
	JTextField radiusTextField;
	JTextField lengthTextField,areaTextField,inputTextField;
	BoxPanel bpRadius,bpLength,bpArea;

public CirclePanel() {
		setLayout(new GridLayout(1,2));
		rightPanel = new KeyJPanel(this);
		leftPanel =new JPanel();

Box box = Box.createVerticalBox();
		bpRadius = new BoxPanel("请输入圆的半径：", 10);
		radiusTextField = bpRadius.getJTextField();

radiusTextField.addFocusListener(this);
		buttonPanel = new JPanel();
		resultButton = new JButton("计算结果：");

resultButton.addActionListener(this);
		clearButton = new JButton("清空");
		clearButton.addActionListener(this);
		buttonPanel.add(resultButton);
		buttonPanel.add(clearButton);
		bpLength = new BoxPanel("圆的周长：", 20);
		lengthTextField = bpLength.getJTextField();
		bpArea = new BoxpPanel("圆的面积：", 20);
		areaTextField = bpArea.getJTextField();

box.add(bpRadius);
		box.add(buttonPanel);
		box.add(bpLength);
		box.add(bpArea);
		leftPanel.add(box);

add(leftPanel);
		add(rightPanel);
	}

public void actionPerformed(ActionEvent e) {

if (e.getSource() == resultButton) {
			try {
				double radius = Double.parseDouble(radiusTextField.getText());
				lengthTextField.setText(""+2*Math.PI*radius);
				areaTextField.setText(""+Math.PI*radius*radius);
			} catch (NumberFormatException e1) {
				JOptionPane.showMessageDialog(this, "请输入数字：","警告对话框",JOptionPane.WARNING_MESSAGE);
			}
		}
		else if (e.getSource() == clearButton) {
			radiusTextField.setText(" ");
		}
	}

public void focusGained(FocusEvent e) {
		inputTextField = (JTextField)e.getSource();
	}

public void focusLost(FocusEvent e) {}

public JTextField getInputTextField() {
		return inputTextField;
	}

}
```

###### 5，三角形计算器的实现（TrianglePanel.java）

```
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;

import javax.swing.Box;
import javax.swing.JButton;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class TrianglePanel extends AbstractPanel implements ActionListener,FocusListener{

JButton resultButton,clearButton;
	JPanel leftPanel,rightPanel,buttonPanel;
	JTextField sideATextField,sideBTextField,sideCTextField;
	JTextField lengthTextField,areaTextField,inputTextField;
	BoxPanel bpSideA,bpSideB,bpSideC,bpLength,bpArea;

public TrianglePanel() {
		setLayout(new GridLayout(1,2));
		rightPanel = new KeyJPanel(this);
		leftPanel =new JPanel();

Box box = Box.createVerticalBox();
		bpSideA = new BoxPanel("请输入三角形的边A：",10);
		sideATextField = bpSideA.getJTextField();

sideATextField.addFocusListener(this);
		bpSideB = new BoxPanel("请输入三角形的边B：",10);
		sideBTextField = bpSideB.getJTextField();
		sideBTextField.addFocusListener(this);
		bpSideC = new BoxPanel("请输入三角形的边C：",10);
		sideCTextField = bpSideC.getJTextField();
		sideCTextField.addFocusListener(this);
		buttonPanel = new JPanel();
		resultButton = new JButton("计算结果：");

resultButton.addActionListener(this);
		clearButton = new JButton("清空");
		clearButton.addActionListener(this);
		buttonPanel.add(resultButton);
		buttonPanel.add(clearButton);

bpLength = new BoxPanel("三角形的周长：", 20);
		lengthTextField = bpLength.getJTextField();
		bpArea = new BoxPanel("三角形的面积：", 20);
		areaTextField = bpArea.getJTextField();

box.add(bpSideA);
		box.add(bpSideB);
		box.add(bpSideC);
		box.add(buttonPanel);
		box.add(bpLength);
		box.add(bpArea);
		leftPanel.add(box);

add(leftPanel);
		add(rightPanel);
	}

public void actionPerformed(ActionEvent e) {

if (e.getSource() == resultButton) {
			try {
				double sideA = Double.parseDouble(sideATextField.getText());
				double sideB = Double.parseDouble(sideBTextField.getText());
				double sideC = Double.parseDouble(sideCTextField.getText());

if ((sideA + sideB>sideC)&&(sideA + sideC>sideB)&&(sideB + sideC>sideA)) {
					double p = (sideA + sideB +sideC)/2.0;
					lengthTextField.setText("" + 2 * p);
					double area = Math.sqrt(p * (p - sideA) * (p - sideB) *(p - sideC));
					areaTextField.setText("" + area);
				}
				else {
					JOptionPane.showMessageDialog(this, "这不构成一个三角形，请重新输入三边","警告对话框",JOptionPane.WARNING_MESSAGE);
				}
			} catch (NumberFormatException e1) {
				JOptionPane.showMessageDialog(this, "请输入数字：","警告对话框",JOptionPane.WARNING_MESSAGE);
			}
		}
		else if (e.getSource() == clearButton) {
			sideATextField.setText(" ");
			sideBTextField.setText(" ");
			sideCTextField.setText(" ");
		}
	}

public void focusGained(FocusEvent e) {
		inputTextField = (JTextField)e.getSource();
	}

public void focusLost(FocusEvent e) {}

public JTextField getInputTextField() {
		return inputTextField;
	}

}
```

###### 6，圆柱计算器的实现（CylinderPanel.java）

```
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;

import javax.swing.Box;
import javax.swing.JButton;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class CylinderPanel extends AbstractPanel implements ActionListener,FocusListener{

JButton resultButton,clearButton;
	JPanel leftPanel,rightPanel,buttonPanel;
	JTextField radiusTextField,highTextField;
	JTextField surfaceAreaTextField,volumeTextField,inputTextField;
	BoxPanel bpRadius,bpHeight,bpSurfaceArea,bpVolume;

public CylinderPanel() {
		setLayout(new GridLayout(1,2));
		rightPanel = new KeyJPanel(this);
		leftPanel =new JPanel();

Box box = Box.createVerticalBox();
		bpRadius = new BoxPanel("请输入圆柱的底面半径：", 10);
		radiusTextField = bpRadius.getJTextField();
		radiusTextField.addFocusListener(this);
		bpHeight = new BoxPanel("请输入圆柱的高：", 10);
		highTextField = bpHeight.getJTextField();
		highTextField.addFocusListener(this);
		buttonPanel = new JPanel();
		resultButton = new JButton("计算结果：");
		resultButton.addActionListener(this);
		clearButton = new JButton("清空");
		clearButton.addActionListener(this);
		buttonPanel.add(resultButton);
		buttonPanel.add(clearButton);
		bpSurfaceArea =  new BoxPanel("圆柱的表面积：", 20);
		this.surfaceAreaTextField = this.bpSurfaceArea.getJTextField();
		bpVolume = new BoxPanel("圆柱的体积：", 20);
		this.volumeTextField = this.bpVolume.getJTextField();
		box.add(bpRadius);
		box.add(bpHeight);
		box.add(buttonPanel);
		box.add(bpSurfaceArea);
		box.add(bpVolume);
		leftPanel.add(box);

add(leftPanel);
		add(rightPanel);
	}

public void actionPerformed(ActionEvent e) {

if (e.getSource() == resultButton) {
			try {
				double radius = Double.parseDouble(radiusTextField.getText());
				double height = Double.parseDouble(highTextField.getText());
				double area = Math.PI * radius *radius;
				surfaceAreaTextField.setText(""+(Math.PI * 2 * radius * height + 2 * area));
				volumeTextField.setText(""+area * height);
			} catch (NumberFormatException e1) {
				JOptionPane.showMessageDialog(this, "请输入数字：","警告对话框",JOptionPane.WARNING_MESSAGE);
			}
		}
		else if (e.getSource() == clearButton) {
			radiusTextField.setText(" ");
			highTextField.setText(" ");
		}
	}

public void focusLost(FocusEvent e) {
		inputTextField = (JTextField)e.getSource();
	}

public void focusGained(FocusEvent e) {}

public JTextField getInputTextField() {
		return inputTextField;
	}

}
```

###### 7，数字软键盘的实现（KeyJPanel.java）

```
import java.awt.Color;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.border.Border;

public class KeyJPanel extends JPanel implements ActionListener{

JButton[] keyButton = new JButton[12];
	String[] num = {"1","2","3","4","5","6","7","8","9","0",".","BackSpace"}; 
	AbstractPanel selectedPanel;
	JTextField inputTextField;

public KeyJPanel(AbstractPanel selectedPanel) {
		this.selectedPanel = selectedPanel;

Border lb = BorderFactory.createLineBorder(Color.gray, 2);
		setBorder(lb);

setLayout(new GridLayout(4,3));

for (int i = 0; i < 12; i++) {
			keyButton[i] = new JButton(num[i]);
			keyButton[i].setFont(new Font("Arial",Font.BOLD,15));
			keyButton[i].setForeground(Color.BLACK);
			keyButton[i].addActionListener(this);
			add(keyButton[i]);
		}

}

public void actionPerformed(ActionEvent e) {
		JButton button = (JButton)e.getSource();

inputTextField = selectedPanel.getInputTextField();

inputNumber(inputTextField,button);
	}

private void inputNumber(JTextField tf, JButton button) {
		String oldString = tf.getText();
		if (oldString == null) {
			tf.setText(" ");
		}
		String subStr = oldString.substring(0,oldString.length() -1);

String newString = button.getText();

if (newString.equals("BackSpace")) {
			tf.setText(subStr);
		}

else if (newString.equals(".")) {
			tf.setText(oldString+".");
		}

else {
			tf.setText(oldString+newString);
		}
	}

}
```

成果截图
</div>

![](https://jrboy.cn/usr/uploads/2019/06/2019060715114862-300x200.png)![](https://jrboy.cn/usr/uploads/2019/06/2019060715120368-300x200.png)

代码展示
</div>