android java --key is same but containsKey return false

manpreet Best Answer 2 years ago

 public class TestClass{
        public String one;
        public String two;
        TestClass(String one, String two){
            this.one=one;
            this.two=two;
        }
    }
    public void testPersonWord(){
        LinkedHashMap<TestClass, Integer> testMap= new LinkedHashMap<>();
        TestClass temp= new TestClass("hdy","hello");
        testMap.put(temp,3);
        TestClass temp2= new TestClass("hdy","hello");
        if(testMap.containsKey(temp2)){
            testMap.replace(temp2,5);
        }else{
            testMap.put(temp2,8);
        }
    }

manpreet 2 years ago

Here is containKey method. The hashCode is used for comparing so definitely the hashCode of two object is difference so it can not be equal.
You can consider to use primitive key or use TestClass.getOne() to compare String.

/**
 * Returns true if this map contains a mapping for the
 * specified key.
 *
 * @param   key   The key whose presence in this map is to be tested
 * @return true if this map contains a mapping for the specified
 * key.
 */
public boolean containsKey(Object key) {
    return getNode(hash(key), key) != null;
}