CODEWITHSUNDEEP
java
Omu
Omu

Reputation: 71188

Can I access an object selected from a Map after the Map has been cleared?

if I have something like this

Map<String, Foo> foos;
...

Foo f = foos.get("key1");
foos.removeAll();

Am I still able to do String s = f.getSomeProperty();

Upvotes: 1

Views: 197

Answers (5)

Sajad Bahmani
Sajad Bahmani

Reputation: 17459

Yes f is Foo object and if Foo have some property that is string use it
Code:

Map<String, Integer> mp = new HashMap<String, Integer>();
mp.put("key1", 48);
mp.put("key2", 50);
mp.put("key3", 52);
mp.put("key4", 54);
mp.put("key5", 56);
mp.put("key6", 58);
Integer mytemp = mp.get("key1");
mp.clear();
System.out.println(mytemp);

Out:

48

that see mytemp is your f that is full object not only pointer

Upvotes: 1

rynmrtn
rynmrtn

Reputation: 3419

The simple answer is yes. f contains a reference to the object that foos.Get("key1") returned (assuming it is non-null). When you remove all from foos, you're simply removing the references from the foos object - you are not actually destroying the data that foos used to contain.

Upvotes: 1

Tarquila
Tarquila

Reputation: 1207

Note that String (note the capital S) is the name of the Java class which represents character strings. But yes, yes you are.

Upvotes: 1

MBO
MBO

Reputation: 30985

foos holds only references to objects, not full objects. If you get something from foos, you get reference to that object and you can modify it. If you remove all elements from foos, then it no longer holds any reference, and those objects can be garbage collected only if there is no other references to that objects.

Upvotes: 11

Andreas Dolk
Andreas Dolk

Reputation: 114757

Yes, you are. You just cleared the map, but the local variable f still holds a valid reference to the Foo and you still can use it.

Upvotes: 6

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