java - 不同类型的for循环结构

Question

这个问题已经有答案了:

why are there two different kinds of for loops in java? (8 个回答)

已关闭 7 年前。

我见过的所有 for 循环基本上如下所示:

for(int i = 0; i < thing.length; i++){
    // Does this each iteration
}

但是在一个项目中，我遇到了(我认为是)如下所示的不同类型的 for 循环。有人可以向我解释这种类型的循环是如何工作的吗？有名字吗？

Component[] squares = getComponents();
for (Component c : squares)
{
    Square s = (Square) c;
    // Set the color of the squares appropriately
    int status = model.getOccupant(s.getRow(), s.getCol());
    if (status == P1)
    {
        s.setColor(P1_COLOR);
    }
    else
    {
        s.setColor(BACKGROUND_COLOR);
    }
}

Answer 1

 for (Component c : squares)
    {
}

The is enhanced for=loop called for-each loop, introduced in release 1.5. Provides good readability of the code, but it misses the index.

When you see the colon (:), read it as “in.” Thus, the loop above reads as “for each element e in elements.” Note that there is no performance penalty for using the for-each loop, even for arrays.

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