赋值的左侧必须是变量 [英] The left-hand side of an assignment must be a variable

问题描述

为什么这不起作用?

private List<Integer> xShot = new ArrayList<Integer>();
     ...codes
     ...codes
     ...codes
     ...codes
     xShot.get(0) += 5;

无法理解为什么赋值的左侧不是变量..

Can't understand why the left-hand side of an assignment´isn't is a variable..

有人帮忙吗?

推荐答案

如果你只是想增加 5 并且不限于 List，你可以避免有争议的冗长 <代码>xShot.set(0, xShot.get(0) + 5) 并改为这样做:

If you just want to increment by 5 and aren't limited to List<Integer> specifically, you could avoid arguably verbose xShot.set(0, xShot.get(0) + 5) and do this instead:

List<AtomicInteger> xShot = new ArrayList<AtomicInteger>();
xShot.get(0).addAndGet(5);

这将增加 AtomicInteger 在 xShot.get(0) 中由 5 就地就位.

This will increment the value of the AtomicInteger in xShot.get(0) by 5 in-place without further ado.

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