java 数据类型转换

int num1=12;
int num2=5;
double result4=num1/(num2+0.0);
System.out.println(result4);//2.4
//
double result5=(double)num1/num2;
System.out.println(result5);//2.4
//
double result6 =(double)(num1/num2);//2.4
System.out.println(result6);//2.0
result4，result5，result6结果如何为2.4 2.4 2.0

double result4=num1/(double)num2;

double result5=((double)num1)/num2;

double result6 =((double)num1)/num2;

or

double result4=num1/(num2/1.0);

double result5=(num1/1.0)/num2;

double result6 =(num1/1.0)/num2;