private static final double is 0

Question

我试图使用以下行来指定一个双常量，任何人都可以帮我解释为什么在运行时这个常量的值为0.0 ：

private static final double CONSTANT = 1/2;

Answer 1

1 and 2 are interpreted as integers and produce integer result of division. Add D at the end to make them interpreted as doubles.

private static final double CONSTANT = 1D/2D;

Answer 2

The constant ends up with a value of 0.0 because the result of integer division is an integer, truncated. So your the value of your initialization is 0 , not 0.5 . To force a double result, make one or both of the operands a double :

private static final double CONSTANT = 1/2.0;  // or 1/2D, or even 1D/2D