什么是“ continue”关键字，它在Java中如何工作？

本文翻译自：What is the “continue” keyword and how does it work in Java?

I saw this keyword for the first time and I was wondering if someone could explain to me what it does.

我第一次看到这个关键字，我想知道是否有人可以向我解释它的作用。

• What is the

  continue

  keyword? 什么是

  continue

  关键字？
• How does it work? 它是如何工作的？
• When is it used? 什么时候使用？

#1楼

参考：https://stackoom.com/question/1dO9/什么是-continue-关键字-它在Java中如何工作

#2楼

As already mentioned

continue

will skip processing the code below it and until the end of the loop.

如前所述，

continue

将跳过对它下面的代码的处理，直到循环结束。

Then, you are moved to the loop's condition and run the next iteration if this condition still holds (or if there is a flag, to the denoted loop's condition).

然后，将您移至循环的条件 ，如果该条件仍然成立（或如果存在标志，则为指定的循环的条件） ，则运行下一个迭代。

It must be highlighted that in the case of

do - while

you are moved to the condition at the bottom after a

continue

, not at the beginning of the loop.

必须强调的是，在

do - while

的情况下

do - while

您在

continue

之后而不是循环开始时移至底部的条件时。

This is why a lot of people fail to correctly answer what the following code will generate.

这就是为什么许多人无法正确回答以下代码将生成什么的原因。

Random r = new Random();
    Set<Integer> aSet= new HashSet<Integer>();
    int anInt;
    do {
        anInt = r.nextInt(10);
        if (anInt % 2 == 0)
            continue;
        System.out.println(anInt);
    } while (aSet.add(anInt));
    System.out.println(aSet);
           

*If your answer is that

aSet

will contain odd numbers only 100%... you are wrong!

*如果您的答案是

aSet

仅包含100％的奇数...您错了！

#3楼

A

continue

statement without a label will re-execute from the condition the innermost

while

or

do

loop, and from the update expression of the innermost

for

loop.

没有标签的

continue

语句将从最里面的

while

或

do

循环的条件以及最里面的

for

循环的更新表达式重新执行。

It is often used to early-terminate a loop's processing and thereby avoid deeply-nested

if

statements.

它通常用于尽早终止循环的处理，从而避免深层嵌套

if

语句。

In the following example

continue

will get the next line, without processing the following statement in the loop.

在下面的示例中，

continue

将获得下一行，而不在循环中处理以下语句。

while (getNext(line)) {
  if (line.isEmpty() || line.isComment())
    continue;
  // More code here
}
           

With a label,

continue

will re-execute from the loop with the corresponding label, rather than the innermost loop.

使用标签时，

continue

将使用相应的标签而不是最内部的循环从循环中重新执行。

This can be used to escape deeply-nested loops, or simply for clarity.

这可用于逃避深度嵌套的循环，或者只是为了清楚起见。

Sometimes

continue

is also used as a placeholder in order to make an empty loop body more clear.

有时，

continue

还用作占位符，以使空循环主体更清晰。

for (count = 0; foo.moreData(); count++)
  continue;
           

The same statement without a label also exists in C and C++.

C和C ++中也存在不带标签的相同语句。

The equivalent in Perl is

next

.

Perl中的等效项是

next

。

This type of control flow is not recommended, but if you so choose you can also use

continue

to simulate a limited form of

goto

.

不建议使用这种类型的控制流，但是如果您选择这样做，也可以使用

continue

模拟有限形式的

goto

。

In the following example the

continue

will re-execute the empty

for (;;)

loop.

在下面的示例中，

continue

将重新执行空的

for (;;)

循环。

aLoopName: for (;;) {
  // ...
  while (someCondition)
  // ...
    if (otherCondition)
      continue aLoopName;
           

#4楼

continue

is kind of like

goto

.

continue

有点像

goto

。

Are you familiar with

break

?

您对

break

熟悉吗？

It's easier to think about them in contrast:

相反，考虑它们会更容易：

• break

  terminates the loop (jumps to the code below it).

  break

  终止循环（跳至其下面的代码）。

• continue

  terminates the rest of the processing of the code within the loop for the current iteration, but continues the loop. 对于当前迭代，

  continue

  终止循环中其余代码的处理，但继续循环。

#5楼

Let's see an example:

让我们来看一个例子：

int sum = 0;
for(int i = 1; i <= 100 ; i++){
    if(i % 2 == 0)
         continue;
    sum += i;
}
                

This would get the sum of only odd numbers from 1 to 100.

这将得到从1到100的仅奇数之和。

#6楼

If you think of the body of a loop as a subroutine,

continue

is sort of like

return

.

如果您将循环的主体视为子程序，则

continue

类似于

return

。

The same keyword exists in C, and serves the same purpose.

C中存在相同的关键字，并且具有相同的用途。

Here's a contrived example:

这是一个人为的示例：

for(int i=0; i < 10; ++i) {
  if (i % 2 == 0) {
    continue;
  }
  System.out.println(i);
}
           

This will print out only the odd numbers.

这只会打印出奇数。