Can Java use String as an index array key? (ex: array["a"]=1;)
Can Java use a String as an index array key? Example:
array["a"] = 1;
No.
To do something like this, you have to use a Map.
Map<String, Integer> aMap = new HashMap<String, Integer>();
aMap.put("a" , Integer.valueOf(1));
No - you want a map to do that:
Map<String, Integer> map = new HashMap<>();
map.put("a", 2);
Then to get it:
int val = map.get("a"); //2
You can only use the square bracket syntax for arrays, not for any of the collections. So something like:
int val = map["a"]; //Compile error
Will always be illegal. You have to use the get()
method.
No, that would be a Map in Java.
(The type would be Map<String,Integer>
.)
No they can't. But they can use chars the ASCII value of the alphabet will be used as the key index
Consider
String[] a = new String['a' + 1];
a['a'] = "Hello";
int[] b = new int['a' + 3];
b['c'] = 5;
System.out.println(a[97]);
System.out.print(b[99]);
This will output
Hello
5
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