新手求助，一个练习题

这个怎么做呢， for循环那个不理解，前面的类型变量我会，就是for循环那个我不懂它想让我干什么

for(int i=0;i<10000;i++){
    System.out.println(i);
}

这道题目的意思就是说

要测试从0-9999所用的时间

public static void main(String[] args){
    long start = System.currentTimeMillis();
    for(int i=0;i<10000;i++){
        System.out.println(i);
    }
    long end = System.currentTimeMillis();
    System.out.println(end-start);
}

public class Test1 {
public static void main(String []args) {
long start = System.currentTimeMillis();
for (int i = 0; i < 9999; i++){
System.out.println(i);
}
long end = System.currentTimeMillis();
System.out.println("end - start = " + Long.toString(end - start) + "ms");
exit();
}

private static void exit() {
    System.out.println("finished!");
}

}

public class Test1 {
        public static void main(String []args) {
        long start = System.currentTimeMillis();
        for (int i = 0; i < 9999; i++){
            System.out.println(i);
        }
        long end = System.currentTimeMillis();
                System.out.println("end - start = " + Long.toString(end - start) + "ms");
            exit();
    }

    private static void exit() {
        System.out.println("finished!");
    }
}

就是让你在控制台把1到9999都输出出来，类似：
1
2
3
4
5
...
9999