Java int += double syntax surprise

2018-06-03 19:52:26

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x += 0.5;

is equivalent to:

x = (int) (x + 0.5)

In general:

x += y is equivalent to x = (type of x) (x + y)

See 15.26.2. Compound Assignment Operators

x += 0.5; is the same as x = (int) (x + 0.5); .

这是因为复合赋值操作符会进行隐式转换 （自动转换）：所以

x+=0.5 => x =(int)(x + 0.5) => x = (int)(7.5) => x = 7

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