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]);
        }
    }
}