java比较器的两种实现

public class compater implements Comparator
{
    
    public int compare(Object arg0, Object arg1)
    {
        TestObject o1 =  null;
        TestObject o2 = null;
        int result = 0;
        if(arg0 instanceof TestObject && arg1 instanceof TestObject){
            o1 = (TestObject)arg0;
            o2 = (TestObject)arg1;
        }
        result = o1.getAge() - o2.getAge();
        return result>0?1:-1;
    }
    
}

public class TestObject implements Comparable<TestObject>
{
        ...

    public int compareTo(TestObject arg0)
    {
        int result = 0;
        TestObject o1 =  null;
        if(arg0 == null)   return -1;
        if(arg0 instanceof TestObject)
        {
            o1 = (TestObject)arg0;
            result = (this.age-o1.getAge())>0?1:-1;
        }
        return result;
    }
}