Double 未转换为 int

Question

This code I have written to convert double into int getting an exception.

Exception in thread "main" java.lang.Error: Unresolved compilation problem: 
Cannot cast from Double to int

This is my code

Double d = 10.9;    
int i = (int)(d);

Answer 1

Double is a wrapper class on top of the primitive double . It can be cast to double , but it cannot be cast to int directly.

If you use double instead of Double , it will compile:

double d = 10.9;    
int i = (int)(d); 

You can also add a cast to double in the middle, like this:

int i = (int)((double)d); 

Answer 2

thats because you cant mix unboxing (converting your Double to a double primitive ) and casting. try

int i = (int)(d.doubleValue());

Answer 3

This

Double d = 10.9;

is your error. You are using wrapper classes instead of data types. Use

double d = 10.9;

Answer 4

You can not cast wrapper like Double to primitive type like int directly.

You can try this -

int i = (int)((double)d);

For more check following link - http://docs.oracle.com/javase/specs/jls/se7/html/jls-5.html