为什么three前不能加int？
public class HelloWorld{
public static void main(String[] args) {
int one = 10 ;
int two = 20 ;
int three = 0 ;
int three=one+two;
System.out.println("three="+three);
int three+=one;
System.out.println("three="+three);
int three-=one;
System.out.println("three="+three);
int three*=one;
System.out.println("three="+three);
int three/=one;
System.out.println("three="+three);
int three%=one;
System.out.println("three="+three);
}
}
