Java优学网while循环教程：从基础语法到实战应用，轻松掌握循环编程

while (条件表达式) {

// 循环体 - 要重复执行的代码

}

int sum = 0; int count = 1; while (count <= 100) {

sum += count;
count++;

} System.out.println("1到100的和是：" + sum);

int i = 0; while (i < 10) {

System.out.println("当前值：" + i);
// 忘记写 i++ 

}

初始化; while (条件) {

// 循环体
更新;

}

int i = 1; while (i <= 9) {

int j = 1;
while (j <= i) {
    System.out.print(j + "×" + i + "=" + (i * j) + "\t");
    j++;
}
System.out.println();  // 换行
i++;

}

import java.util.Scanner;

public class GradeManagement {

public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);
    int totalStudents = 0;
    double totalScore = 0;
    
    System.out.println("请输入学生成绩（输入-1结束）：");
    
    double score = scanner.nextDouble();
    while (score != -1) {
        if (score >= 0 && score <= 100) {
            totalScore += score;
            totalStudents++;
            System.out.println("已录入第" + totalStudents + "个学生成绩：" + score);
        } else {
            System.out.println("成绩无效，请输入0-100之间的分数");
        }
        
        score = scanner.nextDouble();
    }
    
    if (totalStudents > 0) {
        double average = totalScore / totalStudents;
        System.out.println("共录入" + totalStudents + "个学生成绩");
        System.out.println("平均分：" + String.format("%.2f", average));
    } else {
        System.out.println("未录入任何成绩");
    }
    
    scanner.close();
}

}