Binding 2 arraylists android

Question

At first Sorry if title doesn't really explain the problem as it should be.

I have 2 ArrayList in my android (java) code

as example lets say the first is made of strings and the second is made of integers.

ArrayLis<String> strings = new ArrayList<String>();
strings.add("s1");
strings.add("s2");
strings.add("s1");
strings.add("s3");
strings.add("s4");
strings.add("s1");
strings.add("s2");

ArrayList<Integer> ints = new ArrayList<Integer>();
ints.add(1);
ints.add(2);
ints.add(5);
ints.add(3);
ints.add(4);
ints.add(3);
ints.add(2);

Taking this example, lets say each value in array list strings correspond to a value of array ints but the int value might change

I want to remove the repetition in the string array, I used LinkedHashSet to do so:

LinkedHashSet<String>hashset = new LinkedHashSet<>(strings);
strings = new ArrayList<> hashset;

The issue now is i removed the duplicate string entries but i also removed the link between each string and its int value.

how can I get the new "ints" array using the minimal int value for the string for example for s1 that has 1, 5 and 3 as bound values get the 1 value as so:

strings = ["s1", "s2", "s3", "s4"];
ints = [1, 2, ,3, 4];

I thought of using maps. but is it the best way to do it? (map the string to the int and whenever a repetition occures check int if smaller and replace map value)

Mureinik · Accepted Answer · 2020-04-13 07:43:21Z

1

I'd iterate over the string list and convert it to a linked map for the string value to the minimal int. Once that's done, if you really want to, you could re-create the two lists:

Map<String, Integer> map = new LinkedHashMap<>();
for (int index = 0; index < strings.size(); ++i) {
    final int i = index;
    map.compute(
        strings.get(i), (k, v) -> v == null ? ints.get(i) : Math.min(v, ints.get(i)));
}

// If you want two lists again:
strings = new ArrayList<>(map.keySet());
ints = new ArrayList<>(map.values());

edited Apr 13, 2020 at 7:43

answered Apr 11, 2020 at 17:42

Mureinik

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2 Comments

EYakoumi Over a year ago

Thanks for the response. but i faced some issue with it. i am using 1.7 java so lambdas cant be used. also i am targetting os 5 (API 21) and compute will require 24. But i followed the Main idea behind it (the MAP) and it worked with me. Thanks again. (PS: in your response the loop will never be used as it is used on a new map of size 0)

Mureinik Over a year ago

@EYakoumi yikes, thanks for noticing! It was supposed to loop until strings.size(), not map.size(). Edited and fixed.

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