I've a char array:
private char[] chars = "qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM1234567890-_".toCharArray();
I want get a Map when key is char symbol and value is index this char in array. Like this:
{q=0, w=1,....}
I want use a Stream api:
Map<Character, Integer> charToInt = IntStream.rangeClosed(0, chars.length)
But I do not understand what to do next
You can go by this way and use the String instead of its charArray :
private String s = "qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM1234567890-_";
And then create the Map like this :
Map<Character, Integer> charToInt = s.chars()
.mapToObj(i -> (char) i)
.collect(Collectors.toMap(c -> c, c -> s.indexOf(c)));
So create a Map wit as key the char, and as value its index in the String
P.S. We have previous similar answer as I was writing my own. But I keep it as alternative, using Pair class.
To solve this problem, you have to implement Pair class or use any available implementation (as example I give you easiest one):
final class Pair {
private char ch;
private int pos;
public Pair(char ch, int pos) {
this.ch = ch;
this.pos = pos;
}
public char getChar() {
return ch;
}
public int getPos() {
return pos;
}
}
Then you could use streams to solve your problem:
Map<Character, Integer> res = IntStream.range(0, chars.length)
.mapToObj(pos -> new Pair(chars[pos], pos))
.collect(Collectors.toMap(Pair::getChar, Pair::getPos));
If you want to go with IntStream:
Map<Character, Integer> charToInt =
IntStream.rangeClosed(0, chars.length-1)
.mapToObj(i -> Integer.valueOf(i)))
.collect(Collectors
.toMap(i -> Character.valueOf(chars[i]), i -> i));
zipWithIndexwould be useful. Unfortunately Java's streams don't support anything similar yet. Have a look on this question. It might give you a hint what to do.