什么是“：”在这个初学java做的示例程序中使用泛型？ [英] What is ":" doing in this beginners java example program using generics?

问题描述

好的，所以我需要帮助理解一些东西。我明白？：是如何一起使用的，但是阅读了一些Java开始，我发现这种情况在几个地方出现了。最近是这样的...

  public static< U> （box> box）{
 box.add（u）; 
 
 
 
 
 
 
 $ p我很困惑的是：是在做。任何帮助，将不胜感激。我正在Oracle网站的一个页面上看到这个例子： http ：//download.oracle.com/javase/tutorial/java/generics/genmethods.html  
解决方案
是Java的for-each循环结构。这与泛型没有任何关系，或者：不适用于泛型。它的简写如下：为集合中的每个类型框命名框执行以下操作...  
 
 
 
这里是链接到官方文档。
 
 
 
简单的代码示例：（而不是管理泛型执行int数组求和）
 
 
  int [] intArray = {1,5,9,3,5}; 
 int sum = 0; 
 for（int i：intArray）sum + = i; 
 System.out.println（sum）; 
  
 
 
 
 
 
输出：23 
 
 
 
Okay so I need help understanding something. I understand how "? :" are used together but reading over some beginning Java stuff I see this situation popping up in a few places. Most recently is this...
public static <U> void fillBoxes(U u, List<Box<U>> boxes) {
    for (Box<U> box : boxes) {
        box.add(u);
    }
}
What I am confused about is what exactly ":" is doing. Any help would be appreciated. I am looking at this example on a page at Oracle's website, located here: http://download.oracle.com/javase/tutorial/java/generics/genmethods.html
解决方案
That is Java's for-each looping construct. It has nothing to do with generics per-se or: is not for use exclusively with generics. It's shorthand that says: for every type box in the collection named boxes do the following...

Here's the link to the official documentation.

Simpler code sample: (instead of managing generics performing a summation of an int array)
int[] intArray = {1,5,9,3,5};
int sum = 0;
for (int i : intArray) sum += i;
System.out.println(sum);



  
Output: 23


                        
这篇关于什么是“：”在这个初学java做的示例程序中使用泛型？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！