What happens to objects when you redeclare a new object?

Question

... and is there a more proper way of "deleting" them from memory, or is it a case of waiting until the garbage collector in java sweeps them up?
i.e.
private CustomObjectType myObject;
public final void myMethod() {
myObject = new CustomObjectType("I am the first object");
// do some temporary work with myObject
/// now I need to do more work with another temporary object, so just replace the "link"
myObject = new CustomObjectType("I am a second object");
Is it better to declare new variables to hold this second object?
Should a person declare the object to be null when no longer required?
Do I ever need to worry about this, does the garbage collector sort out references for me?
(Please go easy, still learning and don't really need to know this right now but I'm curious! :)

Answer 1

What happens to objects when you redeclare a new object?If you go:
Dog myDog = new Dog();
and then go:
Dog myDog = new Dog();
you are replacing the first reference to Dog() with another one. I don't think it would make sense to do this because it is redundant.
But if you go:
static Dog myDog = new Dog();
and then go:
static Dog myDog = new Dog();
then then second one will be ignored because the first one already assigned Dog() to myDog.. so the second one won't replace the first one - it will just be ignored or generate an error.
is there a more proper way of "deleting" them from memory, or is it a case of waiting until the garbage collector in java sweeps them up?In c and c++ you have to think about when the life of an object ends and destroy the object to prevent a memory leak. But in Java the garbage collector takes this task on if a certain amount of memory is used. If you don't use a lot of memory the gc won't bother and the objects will be destroyed when you exit the program.
You can use:
finalize(){
// insert code to be executed before the gc cleans up
and if you call System.gc() (which you probably won't need to do) then the code in the finalize() method will run first e.g. to erase a picture from the screen before collecting the object.
private CustomObjectType myObject;public final void myMethod() {
myObject = new CustomObjectType("I am the first object");
// do some temporary work with myObject
/// now I need to do more work with another temporary object, so just replace the "link"
myObject = new CustomObjectType("I am a second object");
you could do:
public class CustomObjectType{
    //this constructs an instance of the class using a string of your choice
    CustomObjectType(String str) {
        System.out.println(str);
    static void main(String[] args){
        CustomObjectType myObject = new CustomObjectType("I am the first object");//  This sends the constructor the string you want it to print
        CustomObjectType myObject2 = new CustomObjectType("I am the second object");//  This sends the constructor the string you want it to print
}Bruce eckel wrote Thinking in Java 4th edition considered to be the best book on Java because of how much depth he goes into, although some recommend you should have atleast basic programming knowledge and a committment to learn to get through the book.
I just started it and it helps a lot. Maybe u could borrow it from the library.. good luck!