HashMap.containsKey（）返回false。 为什么？

Question

Here's my code:

class Main{
    static HashMap<Wrapper, Thing> map = new HashMap<Wrapper, Thing>();

    public static void main(String[] args){
        map.put(new Wrapper(1,2,3), new Thing(...));
        System.out.println(map.containsKey(new Wrapper(1, 2, 3)); // prints 'false'
    }

    private static class Wrapper{
        int[] array;
        public Wrapper(int... array){
            this.array = array;
        }
        public boolean equals(Object object){
            if(!(o instanceof Wrapper)) return false;
            return Arrays.equals(this.intervals, ((Wrapper) o).intervals);
        }
    }
}

Why does map.containsKey(new Wrapper(1, 2, 3) return false ?

Answer 1

The hashCodes have to match and unless you override hashCode() it is randomly generated by default.

Try

public int hashCode() { return Arrays.hashCode(array); }