Java中=+和+=的区别？
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Difference between =+ and += in Java?
提问by d0001
Can anyone explain what is happening when you use =+ ?
谁能解释一下当你使用 =+ 时发生了什么？
int one = 1 ;
int two = 2 ;
int sum1 = 0 ;
int sum2 = 0 ;
sum1 =+ one ;
sum2 += two ;
sum1 =+ two ;
sum2 += one ;
System.out.println(sum1) ;
System.out.println(sum2) ;
Output:
输出：
2
3
Why is 1st line 2?
为什么第一行是 2？
回答by Daniel Williams
Java doesn't care too much for white space. =+is being interpreted as =for assignment and +for the unary plus operator which doesn't have any effect here. It is a little used operator and you can read about exactly what it does here http://docs.oracle.com/javase/specs/jls/se8/html/jls-15.html#jls-15.15.3
Java 不太关心空白。=+被解释=为赋值和+一元加运算符，在这里没有任何影响。这是一个很少使用的运算符，您可以在这里阅读它的确切作用http://docs.oracle.com/javase/specs/jls/se8/html/jls-15.html#jls-15.15.3
You can read more about the different operators in Java here https://docs.oracle.com/javase/tutorial/java/nutsandbolts/opsummary.html
您可以在此处阅读有关 Java 中不同运算符的更多信息https://docs.oracle.com/javase/tutorial/java/nutsandbolts/opsummary.html
回答by ΦXoc? ? Пepeúpa ツ
Doing this
这样做
sum1 += one ;
is the same as sum1 = (sum1_type)(sum1 + one);
是相同的 sum1 = (sum1_type)(sum1 + one);
and doing this
并这样做
sum2 =+ two ;
is the same as
是相同的
and doing this sum2 = two;(Unary plus operator; indicates positive value)
and is not affecting the sign of variable two
并且这样做sum2 = two;（一元加运算符；表示正值）并且不影响变量二的符号
