Lazy activation

Lazy activation involves waiting to activate something until it is first used. It's similar to lazy instantiation where instead of creating an instance in advance, you wait until someone actually requests the instance.

For example:class Instantiator {

private Object eagerMember; // we'll use eager instantiation for this one

private Object lazyMember; // we'll use lazy instantiation for this one

public EagerInstatiator() {

// instantiate eager member as soon as this object is created

eagerMember = new String("Big string taking up memory and time upon creation of this");

}

public Object getEagerMember() {

// return immediately, the member is already available

return member1;

}

public Object getLazyMember() {

// instantiate lazyMember only when this method gets called for the first time

if(lazyMember == null) {

lazyMember = new String("Newly created string taking up memory and time upon first request");

}

return lazyMember;

}

}

Herko_ter_Horst at 2007-7-6 21:08:27 >

I think that u r enforcing the Singleton type of situatin using

public Object getLazyMember() {

// instantiate lazyMember only when this method gets called for the first time

if(lazyMember == null) {

lazyMember = new String("Newly created string taking up memory and time upon first request");

}

Butall u have to check is wether " this method gets called for the first time" and for that y u check "lazyMember == null" offcousre only if the method if called for the first time the lazyMember will be null but here single ton kind of situation gets unnecessarily implemented .

As per ur idea lazy instantiation some thing which will happen only during first time methid call r can be said as "instanciated only wen needed" (some thing like late binding) but using if(lazyMember == null) makes it so that U can create only one instance.

Is this rite?

ganeshramhere at 2007-7-6 21:08:27 >

I generally use it for two reasons:

1. faster startup times. If you instantiate all the variables your program is ever going to need right away, it could take a long time for your application to start up. On a smaller scale: all object creation takes time, which is why you want to avoid creating objects you don't need right away.

2. memory usage. Instantiated objects take up space in memory. If you don't need an object right away (or at all), you save memory by not instantiating it.

Herko_ter_Horst at 2007-7-6 21:08:27 >