小编Spm*_*mmr的帖子

public class Primitive {
    public static void main(String []args) {


    byte x=5;
    Double y=(Double)x;  //Error :  Cannot cast from byte to Double.

    Byte n=7;
    Double m=(Double)n; //Error : cannot cast from Byte to Double.

    double c=n; //working right ..."double is primitive and Byte is object ".
    }
}

防止将Byte转换为Double的重点是什么？..如果我没有错,我知道Double to Byte的精确原因.

为什么不能将原始值(例如,double)强制转换为Object(例如,Byte)？

double x = 99;
Byte r = (Byte) x;     // Error: Cannot cast from double to Byte
System.out.println(r);