When is the appropriate time to use the 'new' keyword?

Question

When is it necessary to use the new keyword in Java. I know you are supposed to use it when you create an instance of an object like this:

TextView textView = new TextView(this);

Sometimes in code I notice that new isn't used and I get confused.. In this line of code:

    AssetManager assetManager = getAssets();

Why isn't an instance of the AssetManager created like this:

AssetManager assetManager = new AssetManager();

then it is set equal to getAssests()?

When should new be used?

Thanks!

Answer 1

You use the new keyword when an object is being explicitly created for the first time. Then fetching an object using a getter method new is not required because the object already exists in memory, thus does not need to be recreated.

if you want a more detailed description of new visit the oracle docs

An object will need the 'new' keyword if it is null (which is fancy for not initialized).

EDIT:

This will always print "needs new" under the current circumstances.

Object mObj = null;
if (mObj == null)
    System.out.println("needs new");
else
    System.out.println("does NOT need new");

OUTPUTS: needs new

So to fix it, you would do something like:

Object mObj = new Object();
if (mObj == null)
    System.out.println("needs new");
else
    System.out.println("does NOT need new");
OUTPUTS: does NOT need new

And under those circumstances we will always see "does NOT need neW"