大家好，又见面了，我是你们的朋友全栈君。
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Volume extends JFrame implements ActionListener,ItemListener{
JPanel p1,p2,p3;
JRadioButton rb1,rb2,rb3;
ButtonGroup bg;
JButton b1,b2;
JLabel l1,l2,l3,l4;
JTextField tf1,tf2,tf3,tf4;
public Volume(){
init();
this.add(p1,BorderLayout.NORTH);
this.add(p2,BorderLayout.CENTER);
this.add(p3,BorderLayout.SOUTH);
this.setTitle(“Volume Calculator”);
this.pack();
this.setLocationRelativeTo(null);//窗口居中
this.setVisible(true);
this.setResizable(false);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public void init(){
rb1 = new JRadioButton(“正方体”,true);
rb2 = new JRadioButton(“球 体”);
rb3 = new JRadioButton(“圆柱体”);
rb1.addItemListener(this);
rb2.addItemListener(this);
rb3.addItemListener(this);
rb1.addActionListener(this);
rb2.addActionListener(this);
rb3.addActionListener(this);
bg = new ButtonGroup();
bg.add(rb1);
bg.add(rb2);
bg.add(rb3);
p1 = new JPanel();
p1.setBorder(BorderFactory.createTitledBorder(“选择对象:”));
p1.add(rb1);
p1.add(rb2);
p1.add(rb3);
l1 = new JLabel(“边长:”);
l2 = new JLabel(“半径:”);
l3 = new JLabel(“高:”);
tf1 = new JTextField(4);
tf2 = new JTextField(4);
tf3 = new JTextField(4);
tf1.setEditable(true);
tf2.setEditable(false);
tf3.setEditable(false);
p2 = new JPanel();
p2.setBorder(BorderFactory.createTitledBorder(“输入参数:”));
p2.add(l1);
p2.add(tf1);
p2.add(l2);
p2.add(tf2);
p2.add(l3);
p2.add(tf3);
l4 = new JLabel(“体积:”);
tf4 = new JTextField(12);
tf4.setEditable(false);
b1 = new JButton(“GO”);
b1.addActionListener(this);
b2 = new JButton(“Help”);
b2.addActionListener(this);
p3 = new JPanel();
p3.setBorder(BorderFactory.createTitledBorder(“计算结果:”));
p3.add(b1);
p3.add(l4);
p3.add(tf4);
p3.add(b2);
}
public static void main(String[] args){
JFrame.setDefaultLookAndFeelDecorated(true);
JDialog.setDefaultLookAndFeelDecorated(true);
new Volume();
}
public void clear(){
tf1.setText(“”);
tf2.setText(“”);
tf3.setText(“”);
tf4.setText(“”);
}
public String getText(JTextField tf){
return tf.getText().trim();
}
public void shouDialog(){
JOptionPane.showMessageDialog(this, “参数只能为正数，请不要输入非法字符！”, “警告”, JOptionPane.WARNING_MESSAGE);
clear();
}
public void itemStateChanged(ItemEvent ie){
if(ie.getItem()==rb1){
if(ie.getStateChange()==ItemEvent.SELECTED){
clear();
tf1.setEditable(true);
tf2.setEditable(false);
tf3.setEditable(false);
}
}else if(ie.getItem()==rb2){
if(ie.getStateChange()==ItemEvent.SELECTED){
clear();
tf2.setEditable(true);
tf1.setEditable(false);
tf3.setEditable(false);
}
}else if(ie.getItem()==rb3){
if(ie.getStateChange()==ItemEvent.SELECTED){
clear();
tf2.setEditable(true);
tf3.setEditable(true);
tf1.setEditable(false);
}
}
}
public void actionPerformed(ActionEvent ae){
if(ae.getSource()==b2){//”Help”
new Dialog(this);
}else if(ae.getSource()==b1){//”GO”
double volume = 0;
try{
if(rb1.isSelected()){//正方体
if(!getText(tf1).equals(“”)){
double size = Double.parseDouble(getText(tf1));
if(size>0){
volume = size*size*size;
tf4.setText((double)((int)Math.round(volume*1000)/1000.000) ””);
}else{
shouDialog();
}
}
}else if(rb2.isSelected()){//球体
if(!getText(tf2).equals(“”)){
double radius = Double.parseDouble(getText(tf2));
if(radius>0){
volume = 4*Math.PI* radius*radius*radius/3;
tf4.setText((double)((int)Math.round(volume*1000)/1000.000) ””);
}else{
shouDialog();
}
}
}else if(rb3.isSelected()){//圆柱体
if(!getText(tf2).equals(“”)&&!getText(tf3).equals(“”)){
double radius = Double.parseDouble(getText(tf2));
double height = Double.parseDouble(getText(tf3));
if(radius>0&&height>0){
volume = Math.PI*radius*radius*height;
tf4.setText((double)((int)Math.round(volume*1000)/1000.000) ””);
}else{
shouDialog();
}
}
}
}catch(Exception e){
shouDialog();
}
}
}
}
class Dialog extends JDialog{
JLabel[] l;
JButton b;
JPanel p1,p2,p3;
public Dialog(Frame f){
super(f,true);
p1 = new JPanel(new FlowLayout());
p1.setBorder(BorderFactory.createTitledBorder(“参数描述:”));
p2 = new JPanel(new GridLayout(0,1));
p2.setBorder(BorderFactory.createTitledBorder(“体积公式:”));
p3 = new JPanel(new FlowLayout());
p3.setBorder(BorderFactory.createEtchedBorder());
String[] s = {“a: 边长, r: 半径, h: 高, π: 圆周率(3.14159265..)”,
” 正方体: a*a*a”,
” 球 体: (4/3)*π*r*r*r”,
” 圆柱体: π*r*r*h”,
“Made by Kingpo in Wuhan QQ:281623469”};
l = new JLabel[s.length];
for(int i=1;i
l[i] = new JLabel(s[i]);
p2.add(l[i]);
}
l[0] = new JLabel(s[0]);
p1.add(l[0]);
l[4] = new JLabel(s[4]);
l[4].setFont(new Font(“”,Font.ITALIC,12));
l[4].setForeground(Color.GRAY);
b = new JButton(“OK”);
b.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
setVisible(false);
}
});
p3.add(l[4]);
p3.add(b);
this.add(p1,BorderLayout.NORTH);
this.add(p2,BorderLayout.CENTER);
this.add(p3,BorderLayout.SOUTH);
this.setTitle(“帮助…”);
this.setSize(f.getSize());
this.setResizable(false);
this.setLocationRelativeTo(f);
this.setVisible(true);
}
}
上面是实现了图形用户界面，功能全部实现了，还可以扩展。例如多加几个容器(圆锥体等)对象，多加几个公式(表面积等)。
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