Determine if two Java objects are of the same clas

问题:

I am attempting to do the equivalent of

if ( object1.class == object2.class )
{
    //do something
}  

which of course doesn't work, what method am I overlooking?

回答1:

If they're from the exact same class:

boolean result = object1.getClass().equals( object2.getClass());

Now if they are compatible classes (if one is of a descendent class to the other):

HashMap<String,Object> hashMap = new HashMap<String,Object>();
LinkedHashMap<String,Object> linkedHashMap = new LinkedHashMap<String,Object>();
boolean result = hashMap.getClass().isAssignableFrom( linkedHashMap.getClass() );

As LinkedHashMap is a subclass of HashMap this result variable will be true, so this might probably be better for you as it's going to find exact and subclass matches.

Also, you should avoid using ".class" on variables, as it might not give you the correct result, example:

Object someText = "text value";
System.out.println( someText.class.getName() ); //this will print java.lang.Object and not java.lang.String

When you're using ".class" you're acessing the variable static property and not the class of the object itself.

回答2:

You're missing the getClass() method,

if (object1.getClass().equals(object2.getClass())) 
{ 
    // do something 
}

回答3:

object1.getClass() == object2.getClass()

回答4:

You're looking for the getClass method, defined in java.lang.Class.

(Source: http://download.oracle.com/javase/7/docs/api/java/lang/Class.html)