Java ArrayList 索引
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Java ArrayList Index
提问by Woong-Sup Jung
int[] alist = new int [3];
alist.add("apple");
alist.add("banana");
alist.add("orange");
Say that I want to use the second item in the ArrayList. What is the coding in order to get the following output?
假设我想使用 ArrayList 中的第二项。为了获得以下输出，编码是什么？
output:
输出：
banana
香蕉
采纳答案by Buhake Sindi
You have ArrayListall wrong,
你ArrayList都错了，
- You can't have an integer array and assign a string value.
- You cannot do a
add()method in an array
- 您不能拥有整数数组并分配字符串值。
- 您不能
add()在数组中执行方法
Rather do this:
而是这样做：
List<String> alist = new ArrayList<String>();
alist.add("apple");
alist.add("banana");
alist.add("orange");
String value = alist.get(1); //returns the 2nd item from list, in this case "banana"
Indexing is counted from 0to N-1where Nis size()of list.
索引是从计算0到N-1这里N是size()名单。
回答by Jigar Joshi
回答by AlexR
Exactly as arrays in all C-like languages. The indexes start from 0. So, apple is 0, banana is 1, orange is 2 etc.
就像所有类 C 语言中的数组一样。索引从 0 开始。因此，apple 为 0，banana 为 1，orange 为 2，等等。
回答by stacker
In order to store Strings in an dynamic array (add-method) you can't define it as an array of integers ( int[3] ). You should declare it like this:
为了将字符串存储在动态数组（添加方法）中，您不能将其定义为整数数组（ int[3] ）。你应该这样声明：
ArrayList<String> alist = new ArrayList<String>();
alist.add("apple");
alist.add("banana");
alist.add("orange");
System.out.println( alist.get(1) );
回答by Ralph
Using an Array:
使用数组：
String[] fruits = new String[3]; // make a 3 element array
fruits[0]="apple";
fruits[1]="banana";
fruits[2]="orange";
System.out.println(fruits[1]); // output the second element
Using a List
使用列表
ArrayList<String> fruits = new ArrayList<String>();
fruits.add("apple");
fruits.add("banana");
fruits.add("orange");
System.out.println(fruits.get(1));
回答by Peter Lawrey
Here is how I would write it.
这是我将如何编写它。
String[] fruit = "apple banana orange".split(" ");
System.out.println(fruit[1]);
回答by aksarben
The big difference between primitive arrays & object-based collections (e.g., ArrayList) is that the latter can grow (or shrink) dynamically. Primitive arrays are fixed in size: Once you create them, their size doesn't change (though the contents can).
原始数组和基于对象的集合（例如，ArrayList）之间的最大区别在于后者可以动态增长（或收缩）。原始数组的大小是固定的：创建它们后，它们的大小不会改变（尽管内容可以）。
