Garbage Collector and finalize()

[arefeh]

Hello
I used from Garbage Collector and finalize(), but System.out.println("Error: checked Out"); does not run.

class Book
{
	boolean checkedOut=false;
	
	Book(boolean checkOut)
	{
		checkedOut=checkOut;
		System.out.println("checkedOut is= "+checkedOut);
	}
	void checkIn()
	{
		checkedOut=false;
	}
	protected void finalize()
	{
		if(checkedOut)
		{
			System.out.println("Error: checked Out");
		}
	}
}
public class TerminationCondition
{
	public static void main(String args[])
	{
		Book ob = new Book(true);
		ob.checkIn();
		new Book(true);
		System.gc();
                          [b]//Runtime.gc();has Error![/b]
	}
}

[JosAH]

Hello
I used from Garbage Collector and finalize(), but System.out.println("Error: checked Out"); does not run.

System.gc();
[b]//Runtime.gc();has Error![/b]

What is the exact error you receive? Please don't make us guess; be as exact as possible without guessing yourself.

kind regards,

Jos

[quad64bit]

Also, may I ask why you feel that you need to perform a manual garbage collection cycle? Unless this is just a quick example from a much bigger program, there isn't any reason I can think of that would necessitate calls to garbage collection in this program.

Usually you System.gc(); in between timed tests or when you're working with many megs of data, and even then its generally not required.

[arefeh]

Hello

What is the exact error you receive?....

I get this error:

can not make static reference to method void gc() in class java.lang.Runtime.

Also, may I ask why you feel that you need to perform a manual garbage collection cycle? Unless this is just a quick example from a much bigger program, there isn't any reason I can think of that would necessitate calls to garbage collection in this program.

Usually you System.gc(); in between timed tests or when you're working with many megs of data, and even then its generally not required.

This program is just for practice. when i read a new subject and did not get that result, it became a problem for me.
This is also a question for me that is manual garbage collection is necessary in java?

[quad64bit]

This is also a question for me that is manual garbage collection is necessary in java?

Rarely. I wrote an app that was loading 50+ large images into memory as buffered images, which can rapidly use 1+ gigs of ram. The images were used quickly and discarded, but the garbage collection did not happen rapidly enough to make way for new images in a timely fashion. I made a call to System.gc() in between sets of images to force the collection to occur - this greatly reduced the memory footprint and increased performance.

However, other than in a few very specific test cases (trying to accurately time certain algorithms), I've never used it otherwise. Calling it frequently actually slows your program down, since frequent garbage collection cycles have a lot of overhead.

[JosAH]

I get this error:

can not make static reference to method void gc() in class java.lang.Runtime.

Yes, you didn't read the API documentation for the Runtime class close enough; do this instead:

Runtime.getRuntime().gc();

kind regards,

Jos