Java实现简单计算器、抽票程序

计算器：

 import java.awt.BorderLayout;
 import java.awt.Container;
 import java.awt.Font;
 import java.awt.GridLayout;
 import java.awt.event.ActionEvent;
 import java.awt.event.ActionListener;

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

 public class Calculator extends JFrame implements ActionListener {
     // 属性
     JTextField txtResult;
     String a = "", b = "", operator = "";
     boolean beginDigit = false, beginOperator = false,beginEquals=false;
     //beginDigit记录此次输入前是否输入数字,beginOpertator记录此次输入前是否输入运算符,用于处理多次连续输入运算符的情况（5+-3）
     //beginEquals记录此次输入前是否进行过运算
     public Calculator() {
         setTitle("计算器");
         setSize(240, 270);
         setResizable(false);
         setLocationRelativeTo(null);
         setDefaultCloseOperation(EXIT_ON_CLOSE);

         Container contentPane = this.getContentPane();
         contentPane.setLayout(new BorderLayout(1, 5));
         JPanel pnlNorth = new JPanel();
         JPanel pnlCenter = new JPanel();

         pnlNorth.setLayout(new BorderLayout());
         pnlCenter.setLayout(new GridLayout(4, 4, 3, 3));

         Font font = new Font("Times Roman", Font.BOLD, 20);

         contentPane.add(BorderLayout.NORTH, pnlNorth);
         contentPane.add(BorderLayout.CENTER, pnlCenter);

         txtResult = new JTextField();
         txtResult.setFont(font);
         txtResult.setEnabled(false);
         JButton btnClear = new JButton("C");
         btnClear.setFont(font);
         btnClear.addActionListener(this);

         pnlNorth.add(BorderLayout.CENTER, txtResult);
         pnlNorth.add(BorderLayout.EAST, btnClear);

         String[] captions = { "7", "8", "9", "+", "4", "5", "6", "-", "1", "2", "3", "*", "0", ".", "/", "=", };
         for (int i = 0; i < captions.length; i++) {
             JButton btn = new JButton(captions[i]);
             btn.setFont(font);
             pnlCenter.add(btn);
             btn.addActionListener(this);
         }
     }
     public static void main(String[] args) {
         JFrame frame = new Calculator();
         frame.setVisible(true);
     }

     @Override
     public void actionPerformed(ActionEvent event) {
         String cmd = event.getActionCommand();
         if ("0123456789".contains(cmd)) {
             if(beginEquals==true) {//如果之前已进行过运算，再次直接输入数字就需要进行清空
                 txtResult.setText("");
                 a="";b = "";operator = "";beginDigit=false;
             }
             if (beginDigit == true) {
                 txtResult.setText(txtResult.getText() + cmd);
             } else {
                 txtResult.setText(cmd);
                 beginDigit = true;
                 beginEquals=false;//需要进行置换，不然无法进行上一个if语句
             }
             beginOperator=true;
         }
         if ("+-*/".contains(cmd)) {
             beginEquals=false;
             if (operator != ""&&beginOperator==true) {
                 if (txtResult.getText() != null) {
                     b = txtResult.getText();
                     if ("+".equals(operator)) {
                         a = String.valueOf(Float.parseFloat(a) + Float.parseFloat(b));
                     }if ("-".equals(operator)) {
                         a = String.valueOf(Float.parseFloat(a) - Float.parseFloat(b));
                     }if ("*".equals(operator)) {
                         a = String.valueOf(Float.parseFloat(a) * Float.parseFloat(b));
                     }if ("/".equals(operator)) {
                         a = String.valueOf(Float.parseFloat(a) / Float.parseFloat(b));
                     }
                     operator = cmd;//再次记录运算符
                     txtResult.setText(a);
                 }
             } else {
                 a = txtResult.getText();
                 operator = cmd;
             }
             beginDigit = false;
             beginOperator=false;
         }
         if (".".equals(cmd)) {
             if(txtResult.getText().contains(".")) {
                 JOptionPane.showMessageDialog(null, "不可输入多个小数点！");
                 a=a.substring(0,a.length()-1);//删除多余的小数点
                 txtResult.setText(a);
             }
             txtResult.setText(txtResult.getText() + cmd);
         }
         if ("C".equals(cmd)) {
             txtResult.setText("");
             a = "";
             b = "";
             operator = "";
             beginDigit = false;
             beginOperator=false;
         }
         if ("=".equals(cmd)) {
             b=txtResult.getText();
             if ("+".equals(operator)) {
                 a = String.valueOf(Float.parseFloat(a) + Float.parseFloat(b));
             }if ("-".equals(operator)) {
                 a = String.valueOf(Float.parseFloat(a) - Float.parseFloat(b));
             }if ("*".equals(operator)) {
                 a = String.valueOf(Float.parseFloat(a) * Float.parseFloat(b));
             }if ("/".equals(operator)) {
                 a = String.valueOf(Float.parseFloat(a) / Float.parseFloat(b));
             }
             txtResult.setText(a);
             a=txtResult.getText();
             beginEquals=true;
             beginDigit=false;
             beginOperator=false;
         }
     }
 }

抽奖：

 import java.util.ArrayList;
 import java.util.List;
 import java.util.Random;

 public class Lottery {
     public static void main(String[] args) {
         List<Integer> list=new ArrayList<>();
         int[] result=new int[6];
         for(int i=0;i<32;i++) {
             list.add(i+1);
         }
         Random random=new Random();//记得得初始化一个Random对象
         for(int i=0;i<result.length;i++) {
             // 随机生成一个下标，下标的范围不超过list.size()
             int index=random.nextInt(list.size());
             //将list中下标为index的数删掉
             result[i]=list.remove(index);
         }
         for(int i=0;i<result.length;i++) {
             System.out.printf("%02d ",result[i]);
         }
     }
 }