Question

java编译时错误，需要标识符

public class Hellojava{
puplic static void main(string[] args){
system.out.println("Hello java, I like you.");
}
}
第二行错误，需要标识符，

Answer 1

这个需要两个类，你的Point类没有写，正确却写法是：
Point类：
public class Point{
float x;
float y;
public double distance(Point that){
double xdiff=x-that.x;
double ydiff=y-that.y;
return Math.sqrt(xdiff*xdiff+ydiff*ydiff);
}
}
PointDistance类：
public class PointDistance{
public static void main(String[] args){
Point lowerleft = new Point();
Point upperright=new Point();
lowerleft.x = 0;
lowerleft.y = 0;
upperright.x = 100;
upperright.y = 100;
double d=lowerleft.distance(upperright);
System.out.println("the distance between both points is"+d);
}
}

这两个类应该在同一个文件夹下。

Answer 2

java连连看~，第二行public 关键字拼错 ， main方法中参数类型s为大写，第三行第一个s大写，完毕~

Answer 3

把system改成System试试。

Answer 4

拼写错误，public，不是puplic

Answer 5

system 应该大写开头System