for(String str :list){ }
时间: 2024-06-05 09:06:40 浏览: 7
This is a for-each loop in Java, also known as an enhanced for loop. It is used to iterate through a collection of objects, such as an array or ArrayList, and perform an action on each element in the collection.
In this specific code, the collection being iterated through is called "list", which is likely an ArrayList or another type of collection. The loop iterates through each element in the collection and assigns it to the variable "str". The code inside the loop would then perform some action on "str".
相关问题
JAVA中for(String str: list) 是什么意思
### 回答1:
Java中的`for-each`循环语法格式为`for (type variable : collection) { ... }`,其中`type`是指集合中元素的数据类型,`variable`是指在循环中用来表示集合中当前元素的变量名,`collection`则是指要进行遍历的集合。
换句话说,`for-each`循环用于遍历一个集合中的所有元素,而不需要使用传统的`for`循环中的索引变量。在每次循环中,变量`variable`会被赋值为集合中的下一个元素,直到所有元素都被遍历完为止。
例如,如果有一个`List`类型的集合对象`list`,可以使用`for-each`循环遍历它的所有元素:
```
List<String> list = new ArrayList<>();
list.add("apple");
list.add("banana");
list.add("orange");
for (String str : list) {
System.out.println(str);
}
```
输出结果将会是:
```
apple
banana
orange
```
在循环中,变量`str`会被分别赋值为`"apple"`、`"banana"`和`"orange"`,然后在每次循环中使用`System.out.println()`语句打印出来。
### 回答2:
在JAVA中,for(String str: list) 是一种增强的for循环语法,用于遍历集合或数组中的元素。其中,String是集合或数组中元素的类型,str是循环迭代变量,list是要遍历的集合或数组。
使用这种循环语法,可以方便地遍历集合或数组,不需要手动使用索引或迭代器来访问每个元素。循环每次迭代时,将集合或数组中的一个元素赋值给迭代变量str,执行循环体内的代码,然后进入下一次循环,直到遍历完所有的元素。
例如,如果有一个ArrayList<String>类型的集合list,其中包含了多个字符串元素。可以使用以下代码来遍历集合中的每个元素并打印出来:
for(String str: list) {
System.out.println(str);
}
这段代码会依次取出list中的每个元素赋值给str,然后打印出来。在循环的每次迭代中,str都会指向list中的一个元素,直到遍历完集合中的所有元素为止。
使用for(String str: list)语法,可以简化代码,提高可读性,减少出错的可能性,特别是在遍历集合或数组时非常实用。
for(String str:res)
This is a for-each loop in Java used to iterate through a collection of elements. In this case, the collection is an array or list of Strings named "res".
The loop iterates through each element of the collection, assigning it to the variable "str" for each iteration.
Here's an example code snippet to illustrate how it works:
```
String[] res = {"apple", "banana", "cherry"};
for(String str:res){
System.out.println(str);
}
// Output:
// apple
// banana
// cherry
```
In this example, the for-each loop will iterate through each element in the "res" array and print it to the console. The variable "str" is assigned to each element in turn, so "apple" is printed first, then "banana", and finally "cherry".