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javaarraysarraylistcontains

Using contains on an ArrayList with integer arrays

I have an ArrayList<int[]>, and I add an array to it.

ArrayList<int[]> j = new ArrayList<int[]>();
int[] w = {1,2};
j.add(w);

Suppose I want to know if j contains an array that has {1,2} in it without using w, since I will be calling it from another class. So, I create a new array with {1,2} in it...

int[] t = {1,2};
return j.contains(t);

...but this would return false even though w was added to the list, and w contains the exact same array as t.

Is there a way to use contains such that I can just check to see if one of the elements of the ArrayList has the array value {1,2}?

Solution

  • Arrays can only be compared with Arrays.equals().

    You probably want an ArrayList of ArrayLists.

    ArrayList<ArrayList<Integer>> j = new ArrayList<ArrayList<Integer>>();
ArrayList<Integer> w = new ArrayList<Integer>();
w.add(1); w.add(2);
j.add(w);
ArrayList<Integer> t = new ArrayList<Integer>();
t.add(1); t.add(2);
return j.contains(t); // should return true.