java 的问题...

这个是我自己想着玩编的，高手看看错在哪里啊，编译器说是identifier expected
class People{
folat size;
folat height;
String name;
folat IBM;
IBM=height/(size*size);
void healthTest(){
if(IBM>30.0f){
System.out.println("你太胖了!");
}else if(IBM>20.0f){
System.out.println(" Well done!");
}else {
System.out.println("你太瘦了");
}
}
}
public class HealthTest{
public void main(String[] args){
People[] young=new People[3];
young[0].name="Frank";
young[1].name="Rose";
young[2].name="Jack";
young[0].size=85.0f;
young[1].size=60.0f;
young[2].size=50.0f;
young[0].height=180.0f;
young[1].height=170.0f;
young[2].height=165.0f;
int x=0;
while(x<3){
young[x].healthTest();
x=x+1;
}
}
}

class People{
float size; //folat是啥类型？是float吧
float height; //folat是啥类型？是float吧
String name; //folat是啥类型？是float吧
float IBM;//folat是啥类型？是float吧

void healthTest(){
IBM=height/(size*size);//把这段话拿下来了
if(IBM>30.0f){
System.out.println("你太胖了!");
}else if(IBM>20.0f){
System.out.println(" Well done!");
}else {
System.out.println("你太瘦了");
}
}
}
public class HealthTest{
public static void main(String[] args){ //你的main方法没static
People[] young=new People[3];
young[0].name="Frank";
young[1].name="Rose";
young[2].name="Jack";
young[0].size=85.0f;
young[1].size=60.0f;
young[2].size=50.0f;
young[0].height=180.0f;
young[1].height=170.0f;
young[2].height=165.0f;
int x=0;
while(x<3){
young[x].healthTest();
x=x+1;