Welcome to the World of Programming: Your Java Journey Begins

Java is a general-purpose, object-oriented, class-based programming language known for its robustness, reliability, and platform independence. This tutorial introduces the basics of Java, including syntax and a practical case - calculating pi using Monte Carlo simulation. First set the random seed, then simulate the throwing point, calculate the distance to the center of the circle and determine whether the point is within the circle. Finally, calculate pi and output the result.

Welcome to the world of programming: start your Java journey

Introduction

Today, we start the exciting journey of Java programming. Java is a general-purpose, object-oriented, class-based programming language known for its robustness, reliability, and platform independence. In this tutorial, we'll walk through the basics of Java step by step and explore a practical case to let you experience the power of programming first-hand.

Java Basics

// Java 基础语法
class MyClass {
    public static void main(String[] args) {
        System.out.println("欢迎来到 Java 世界！");
    }
}

Practical Case: Calculating Pi

Let us write a Java program to calculate pi . We will use Monte Carlo simulation to estimate the ratio of π areas to approximate π.

import java.util.Random;

public class PiCalculator {

    public static void main(String[] args) {
        // 设置随机种子
        Random random = new Random();

        // 模拟次数
        int numPoints = 100000;

        // 圆心坐标
        double centerX = 0;
        double centerY = 0;

        // 半径
        double radius = 1;

        // 点在圆内的计数
        int countInCircle = 0;

        // 模拟投掷点
        for (int i = 0; i < numPoints; i++) {
            // 生成随机点
            double x = random.nextDouble() * 2 * radius - radius;
            double y = random.nextDouble() * 2 * radius - radius;

            // 计算到圆心的距离
            double distance = Math.sqrt(x * x + y * y);

            // 判断点是否在圆内
            if (distance <= radius) {
                countInCircle++;
            }
        }

        // 计算圆周率π
        double pi = 4.0 * countInCircle / numPoints;

        // 输出结果
        System.out.println("近似值 π = " + pi);
    }
}

Save this code as a PiCalculator.java file and compile it using the command javac PiCalculator.java. Then, run the program via java PiCalculator. You will see an estimate of π printed on the console.

Congratulations on taking the first step in your Java programming journey! Keep learning and explore more features of Java.

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