List< String>的迭代与modyfing字符串 [英] Iteration of List<String> with modyfing String

问题描述

我不能修改List的这种方式的元素：

  for（String s：list）
 { 
s =x+ s; 
} 
  

执行后此列表的代码元素不变
如何 c >对象是不可变的，你不能改变你迭代的值。此外，你不能修改在这样的循环中迭代的列表。唯一的方法是使用标准循环迭代列表索引或使用 ListIterator 接口：

  for（int i = 0; i  {
 list.set（i，x+ list。 get（i））; 
} 
 
 for（ListIterator i = list.listIterator（）; i.hasNext（）;）
 {
 i.set（x+ i。下一个（））; 
} 
  

I can't modyfing element of List this way:

for (String s : list)
{
   s = "x" + s;
}

After execution this code elements of this list are unchanged How to achieve iteration with modyfing through List in the simplest way.

解决方案

Since String objects are immutable, you cannot change the values you're iterating over. Furthermore, you cannot modify the list you're iterating over in such a loop. The only way to do this is to iterate over the list indexes with a standard loop or to use the ListIterator interface:

for (int i = 0; i < list.size(); i++)
{
    list.set(i, "x" + list.get(i));
}

for (ListIterator i = list.listIterator(); i.hasNext(); )
{
    i.set("x" + i.next());
}

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