Java课堂

import java.awt.*;
import java.awt.event.*;
import java.util.*;


public class Main{

    public static double max(double...values)
    {
        double largest=Double.MIN_VALUE;
        for (double v:values)
            if(v>largest) largest=v;
        return largest;
    }

    public static void main(String args[]) {

        System.out.println("Max:"+max(1,11,300,2,3));

    }
}

// MethodOverload.java
// Using overloaded methods

public class Main {

    public static void main(String[] args) {
        System.out.println("The square of integer 7 is " + square(7));
        System.out.println("\nThe square of double 7.5 is " + square(7.5));
    }

    public static int square(int x) {
        return x * x;
    }

    public static double square(double y) {
        return y * y;
    }
}

import java.math.BigInteger;
import java.util.Scanner;


public class CalculateN {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		System.out.print("请输入N：");
		Scanner scanner=new Scanner(System.in);
		int number=scanner.nextInt();
		System.out.println(number+"!="+calculateN2(number));
		
	}
	
	public static long calculateN(int n) {
		if(n==1 || n==0){
			return 1;
		}
		
		return n*calculateN(n-1);
	}

	public static BigInteger calculateN2(int n) {
		if(n==1 || n==0){
			return BigInteger.valueOf(1);
		}
		return BigInteger.valueOf(n).multiply(calculateN2((n-1)));
	}
}

import java.util.Random;

public class Main
{
    public static void main(String[] args)
    {
        Random r1 = new Random(50);
        System.out.println("第一个种子为50的Random对象");
        System.out.println("r1.nextBoolean():\t" + r1.nextBoolean());
        System.out.println("r1.nextInt():\t\t" + r1.nextInt());
        System.out.println("r1.nextDouble():\t" + r1.nextDouble());
        System.out.println("r1.nextGaussian():\t" + r1.nextGaussian());
        System.out.println("---------------------------");

        Random r2 = new Random(50);
        System.out.println("第二个种子为50的Random对象");
        System.out.println("r2.nextBoolean():\t" + r2.nextBoolean());
        System.out.println("r2.nextInt():\t\t" + r2.nextInt());
        System.out.println("r2.nextDouble():\t" + r2.nextDouble());
        System.out.println("r2.nextGaussian():\t" + r2.nextGaussian());
        System.out.println("---------------------------");

        Random r3 = new Random(100);
        System.out.println("种子为100的Random对象");
        System.out.println("r3.nextBoolean():\t" + r3.nextBoolean());
        System.out.println("r3.nextInt():\t\t" + r3.nextInt());
        System.out.println("r3.nextDouble():\t" + r3.nextDouble());
        System.out.println("r3.nextGaussian():\t" + r3.nextGaussian());


        Random r4 = new Random(System.currentTimeMillis());
        System.out.println("以当前时间为种子的Random对象");
        System.out.println("r3.nextBoolean():\t" + r4.nextBoolean());
        System.out.println("r3.nextInt():\t\t" + r4.nextInt());
        System.out.println("r3.nextDouble():\t" + r4.nextDouble());
        System.out.println("r3.nextGaussian():\t" + r4.nextGaussian());
    }
}

import java.util.*;

public class Main
{
    public static void main(String[] args)
    {
        Random rand = new Random();
        System.out.println("rand.nextBoolean()：" + rand.nextBoolean());
        byte[] buffer = new byte[16];
        rand.nextBytes(buffer);
        System.out.println(Arrays.toString(buffer));
        //生成0.0~1.0之间的伪随机double数
        System.out.println("rand.nextDouble()：" + rand.nextDouble());
        //生成0.0~1.0之间的伪随机float数
        System.out.println("rand.nextFloat()：" + rand.nextFloat());
        //生成平均值是 0.0，标准差是 1.0的伪高斯数
        System.out.println("rand.nextGaussian()：" + rand.nextGaussian());
        //生成一个处于long整数取值范围的伪随机整数
        System.out.println("rand.nextInt()：" + rand.nextInt());
        //生成0~26之间的伪随机整数
        System.out.println("rand.nextInt(26)：" + rand.nextInt(26));
        //生成一个处于long整数取值范围的伪随机整数
        System.out.println("rand.nextLong()：" +  rand.nextLong());
    }
}

public class Main
{
    public static void main(String[] args)
    {
        /*---------下面是三角运算---------*/
        //将弧度转换角度
        System.out.println("Math.toDegrees(1.57)：" + Math.toDegrees(1.57));
        //将角度转换为弧度
        System.out.println("Math.toRadians(90)：" + Math.toRadians(90));
        //计算反余弦，返回的角度范围在 0.0 到 pi 之间。
        System.out.println("Math.acos(0.3)：" + Math.acos(1.2));
        //计算反正弦；返回的角度范围在 -pi/2 到 pi/2 之间。 
        System.out.println("Math.asin(0.8)：" + Math.asin(0.8));
        //计算反正切；返回的角度范围在 -pi/2 到 pi/2 之间。 
        System.out.println("Math.atan(2.3)：" + Math.atan(2.3));
        //计算三角余弦。
        System.out.println("Math.cos(1.57)：" + Math.cos(1.57));
        //计算值的双曲余弦。 
        System.out.println("Math.cosh(1.2 )：" + Math.cosh(1.2 ));
        //计算正弦
        System.out.println("Math.sin(1.57 )：" + Math.sin(1.57 ));
        //计算双曲正弦
        System.out.println("Math.sinh(1.2 )：" + Math.sinh(1.2 ));
        //计算三角正切
        System.out.println("Math.tan(0.8 )：" + Math.tan(0.8 ));
        //计算双曲余弦
        System.out.println("Math.tanh(2.1 )：" + Math.tanh(2.1 ));
        //将矩形坐标 (x, y) 转换成极坐标 (r, thet));，返回所得角 theta。 
        System.out.println("Math.atan2(0.1, 0.2)：" + Math.atan2(0.1, 0.2));
        /*---------下面是取整运算---------*/
        //取整，返回小于目标数的最大整数。
        System.out.println("Math.floor(-1.2 )：" + Math.floor(-1.2 ));
        //取整，返回大于目标数的最小整数。
        System.out.println("Math.ceil(1.2)：" + Math.ceil(1.2));
        //四舍五入取整
        System.out.println("Math.round(2.3 )：" + Math.round(2.3 ));
        /*---------下面是乘方、开方、指数运算---------*/
        //计算平方根。
        System.out.println("Math.sqrt(2.3 )：" + Math.sqrt(2.3 ));
        //计算立方根。 
        System.out.println("Math.cbrt(9)：" + Math.cbrt(9));
        //返回欧拉数 e 的n次幂。
        System.out.println("Math.exp(2)：" + Math.exp(2));
        //返回 sqrt(x2：" +y2)，没有中间溢出或下溢。
        System.out.println("Math.hypot(4 , 4)：" + Math.hypot(4 , 4));
        // 按照 IEEE 754 标准的规定，对两个参数进行余数运算。
        System.out.println("Math.IEEEremainder(5 , 2)：" + Math.IEEEremainder(5 , 2));
        //计算乘方
        System.out.println("Math.pow(3, 2)：" + Math.pow(3, 2));
        //计算自然对数
        System.out.println("Math.log(12)：" + Math.log(12));
        //计算底数为 10 的对数。
        System.out.println("Math.log10(9)：" + Math.log10(9));
        // 回参数与 1 之和的自然对数。 
        System.out.println("Math.log1p(9)：" + Math.log1p(9));
        /*---------下面是符号相关的运算---------*/
        //计算绝对值。
        System.out.println("Math.abs(-4.5)：" + Math.abs(-4.5));
        //符号赋值，返回带有第二个浮点数符号的第一个浮点参数。
        System.out.println("Math.copySign(1.2, -1.0)：" + Math.copySign(1.2, -1.0));
        //符号函数；如果参数为 0，则返回 0；如果参数大于 0，则返回 1.0；如果参数小于 0，则返回 -1.0。
        System.out.println("Math.signum(2.3)：" + Math.signum(2.3));
        /*---------下面是大小相关的运算运算---------*/
        //找出最大值
        System.out.println("Math.max(2.3 , 4.5)：" + Math.max(2.3 , 4.5));
        //计算最小值 
        System.out.println("Math.min(1.2 , 3.4)：" + Math.min(1.2 , 3.4));
        //返回第一个参数和第二个参数之间与第一个参数相邻的浮点数。
        System.out.println("Math.nextAfter(1.2, 1.0)：" + Math.nextAfter(1.2, 1.0));
        //返回比目标数略大的浮点数
        System.out.println("Math.nextUp(1.2 )：" + Math.nextUp(1.2 ));
        //返回一个伪随机数，该值大于等于 0.0 且小于 1.0。
        System.out.println("Math.random()：" + Math.random());
    }
}

public class Main{

    public static void main(String[] args) {
        int result;

        for (int x = 1; x <= 10; x++) {
            result = square(x);
            // Math库中也提供了求平方数的方法
            // result=(int)Math.pow(x,2);
            System.out.println("The square of " + x + " is " + result + "\n");
        }
    }

    // 自定义求平方数的静态方法
    public static int square(int y) {
        return y * y;
    }
}

// RollDie.java
// Roll a six-sided die 6000 times
import javax.swing.*;

public class Main {
    public static void main( String args[] )
    {
        int frequency1 = 0, frequency2 = 0,
                frequency3 = 0, frequency4 = 0,
                frequency5 = 0, frequency6 = 0, face;

        // summarize results
        for ( int roll = 1; roll <= 6000; roll++ ) {
            face = 1 + (int) ( Math.random() * 6 );

            switch ( face ) {
                case 1:
                    ++frequency1;
                    break;
                case 2:
                    ++frequency2;
                    break;
                case 3:
                    ++frequency3;
                    break;
                case 4:
                    ++frequency4;
                    break;
                case 5:
                    ++frequency5;
                    break;
                case 6:
                    ++frequency6;
                    break;
            }
        }

        JTextArea outputArea = new JTextArea( 7, 10 );

        outputArea.setText(
                "Face\tFrequency" +
                        "\n1\t" + frequency1 +
                        "\n2\t" + frequency2 +
                        "\n3\t" + frequency3 +
                        "\n4\t" + frequency4 +
                        "\n5\t" + frequency5 +
                        "\n6\t" + frequency6 );

        JOptionPane.showMessageDialog( null, outputArea,
                "Rolling a Die 6000 Times",
                JOptionPane.INFORMATION_MESSAGE );
        System.exit( 0 );
    }
}

// RandomInt.java
// Shifted, scaled random integers
import javax.swing.JOptionPane;

public class Main {
    public static void main( String args[] )
    {
        int value;
        String output = "";

        for ( int i = 1; i <= 20; i++ ) {
            value = 1 + (int) ( Math.random() * 6 );
            output += value + "  ";

            if ( i % 5 == 0 )
                output += "\n";
        }

        JOptionPane.showMessageDialog( null, output,
                "20 Random Numbers from 1 to 6",
                JOptionPane.INFORMATION_MESSAGE );

        System.exit( 0 );
    }
}

import java.util.Random;
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        int n=10000;
        Scanner scanner = new Scanner(System.in);
        int totalQuestions = 30;
        int correctAnswers = 0;
        int wrongAnswers = 0;
        int countdownSeconds = 100; // 设置倒计时秒数
//        CountdownTimer countdownTimer = new CountdownTimer(countdownSeconds);
//        countdownTimer.start();
        for (int i = 1; i <= totalQuestions; i++) {
            System.out.println("问题 " + i + ":");
            String question = generateQuestion();
            System.out.println(question);


            int userAnswer = scanner.nextInt();
            int correctAnswer = evaluateQuestion(question);




            while (userAnswer == correctAnswer)
            {
                System.out.println("回答正确!\n");
                System.out.println("倒计时\n"+n);
                n-=5;
                correctAnswers++;

                break;

            }

            while(userAnswer != correctAnswer)
            {
                System.out.println("回答错误。正确答案是: " + correctAnswer + "\n");
                System.out.println("倒计时\n"+n);
                n-=3;
                wrongAnswers++;
                break;
            }

        }



        double accuracy = (double) correctAnswers / totalQuestions * 100;
        System.out.println("答题结束。正确答案数量: " + correctAnswers);
        System.out.println("错误答案数量: " + wrongAnswers);
        System.out.println("正确率: " + accuracy + "%");

        scanner.close();
    }


    private static int Judge(int a,int b,int c) {
        if(a==b){
            System.out.println("回答正确!\n");
            b++;
            return 0;
        }else{
            System.out.println("回答错误，正确答案是："+b+"\n");
            c++;
        }
        return 0;
    }





    // 生成随机四则运算题目
    private static String generateQuestion() {
        Random random = new Random();
        int num1 = random.nextInt(100);
        int num2 = random.nextInt(100);
        int operator = random.nextInt(4);

        String op = "";
        int answer = 0;

        switch (operator) {
            case 0: // Addition
                op = "+";
                answer = num1 + num2;
                break;
            case 1: // Subtraction
                op = "-";
                answer = num1 - num2;
                if (answer < 0) {
                    // 确保减法不出现负数
                    num1 = num2 + random.nextInt(1000 - num2); // 重新生成num1
                    answer = num1 - num2;
                }
                break;
            case 2: // Multiplication
                op = "x";
                num1 = random.nextInt(100);
                num2 = random.nextInt(100);
                answer = num1 * num2;
                if (answer >= 10000) {
                    // 确保乘法不出现4位数
                    num1 = random.nextInt(100);
                    num2 = random.nextInt(100);
                    answer = num1 * num2;
                }
                break;
            case 3: // Division
                op = "/";
                num2 = random.nextInt(10) + 1; // 避免除以0
                num1 = num2 * random.nextInt(100);
                answer = num1 / num2;
                break;
        }

        return num1 + " " + op + " " + num2 + " = ";
    }

    // 计算四则运算题目的答案
    private static int evaluateQuestion(String question) {
        String[] parts = question.split(" ");
        int num1 = Integer.parseInt(parts[0]);
        String operator = parts[1];
        int num2 = Integer.parseInt(parts[2]);

        switch (operator) {
            case "+":
                return num1 + num2;
            case "-":
                return num1 - num2;
            case "x":
                return num1 * num2;
            case "/":
                return num1 / num2;
            default:
                throw new IllegalArgumentException("无效的运算符: " + operator);
        }
    }
}

<!DOCTYPE html>
<html>
<head>
    <title>User Login</title>
    <style>
        .container {
            width: 300px;
            margin: 0 auto;
            padding: 20px;
            border: 1px solid #ccc;
            text-align: center;
        }
        .input-group {
            margin-bottom: 10px;
        }
        .input-group label {
            display: block;
            margin-bottom: 5px;
        }
        .input-group input {
            width: 100%;
            padding: 5px;
        }
        .input-group img {
            margin-top: 10px;
        }
        .input-group button {
            width: 100%;
            padding: 7px;
            background-color: #4CAF50;
            color: white;
            border: none;
        }
    </style>
    <script>
        function generateCaptcha() {
            var captcha = '';
            var characters = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
            var captchaLength = 4;
            for (var i = 0; i < captchaLength; i++) {
                captcha += characters.charAt(Math.floor(Math.random() * characters.length));
            }
            // Display the generated captcha
            document.getElementById('captcha').textContent = captcha;
            // Update the captcha image source with the generated captcha
            document.getElementById('captchaImage').src = 'https://dummyimage.com/150x50/000/fff&text=' + captcha;
        }

        function validateForm(event) {
            event.preventDefault(); // Prevent form submission
            var captchaInput = document.getElementById('captchaInput').value;
            var captchaLabel = document.getElementById('captcha').textContent;
            if (captchaInput.toUpperCase() === captchaLabel.toUpperCase()) {
                // Correct captcha, perform actions for successful login
                alert('Login successful!');
                // Redirect to success page here

                // Clear form data
                document.getElementById('username').value = '';
                document.getElementById('password').value = '';
                document.getElementById('captchaInput').value = '';

                // Generate a new captcha
                generateCaptcha();
            } else {
                // Incorrect captcha, show error message
                alert('Incorrect captcha!');
                // Clear captcha input
                document.getElementById('captchaInput').value = '';
                // Generate a new captcha
                generateCaptcha();
            }
        }
    </script>
</head>
<body onload="generateCaptcha()">
<div class="container">
    <h2>User Login</h2>
    <form action="/login" method="post" onsubmit="validateForm(event)">
        <div class="input-group">
            <label for="username">Username:</label>
            <input type="text" id="username" name="username" required>
        </div>
        <div class="input-group">
            <label for="password">Password:</label>
            <input type="password" id="password" name="password" required>
        </div>
        <div class="input-group">
            <label for="captcha">Captcha:</label>
            <input type="text" id="captchaInput" name="captcha" required>
            <span id="captcha"></span>
            <img src="" alt="Captcha" id="captchaImage">
            <button type="button" onclick="generateCaptcha()">Refresh</button>
        </div>
        <div class="input-group">
            <button type="submit">Login</button>
        </div>
    </form>
</div>
</body>
</html>

posted @ 2023-09-24 21:12 软件拓荒人阅读(23) 评论(0) 收藏举报

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