问题
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?
output:
banana
回答1:
You have ArrayList all wrong,
- You can't have an integer array and assign a string value.
- You cannot do a
add()method in an array
Rather do this:
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 0 to N-1 where N is size() of list.
回答2:
Read more about Array and ArrayList
List<String> aList = new ArrayList<String>();
aList.add("apple");
aList.add("banana");
aList.add("orange");
String result = alist.get(1); //this will retrieve banana
Note: Index starts from 0 i.e. Zero
- Resource
回答3:
Using an Array:
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
ArrayList<String> fruits = new ArrayList<String>();
fruits.add("apple");
fruits.add("banana");
fruits.add("orange");
System.out.println(fruits.get(1));
回答4:
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:
ArrayList<String> alist = new ArrayList<String>();
alist.add("apple");
alist.add("banana");
alist.add("orange");
System.out.println( alist.get(1) );
回答5:
Exactly as arrays in all C-like languages. The indexes start from 0. So, apple is 0, banana is 1, orange is 2 etc.
回答6:
Here is how I would write it.
String[] fruit = "apple banana orange".split(" ");
System.out.println(fruit[1]);
回答7:
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).
来源：https://stackoverflow.com/questions/4313457/java-arraylist-index