Java:在循环中声明对象 [英] Java : declaring objects in a loop

问题描述

两者之间是否有任何区别

Is there any difference between

for (...) {
  String temp = "temp";
}

和

String temp;
for (...) {
  temp = "temp";
}

我的意思是，Java是否会浪费很多资源来循环创建/删除对象?

I mean, does Java waste many resources creating/deleting objects in loop?

谢谢.

推荐答案

差异在于变量的作用域.

• 在循环内部定义是指仅在循环内部可见.

• Defined inside loop means visible only inside the loop.

在循环外部定义意味着在循环内部和外部可见.

Defined outside the loop means visible inside and outside the loop.

Java是否会浪费很多资源来循环创建/删除对象?

does Java waste many resources creating/deleting objects in loop?

如果在循环内定义，那么它将在每次迭代时重新初始化，这意味着额外的可执行语句.如果您想在每次迭代时重新初始化它，那么最好将其移出以保存该语句所浪费的cpu.

if defined inside the loop then it will be re-intialized with every iteration, which means an extra executable statement. If you want to re-intialize it with each iteration then good otherwise move it out to save wasted cpu for that statement.

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