Thread: Break it down

Ok, first of all the first line has a few syntax errors. It should be this:

class Car{}

This basically tells Java that you are creating a class named Car. Anything between the curly brackets defines what a Car is, and how it can be used. It's a dummy class because there's nothing in there

Car[] cars1;

This is NOT a null reference. Instead, this is a variable declaration. Variable declarations tell the compiler that you may sometime in the future want to use a variable called cars1, which holds an array of Car.

Car[] cars2 = new Car[10];

Again, this is not a null reference. Instead, this is another variable declaration, with an instantiation. Instantiation simply means setting the variable to that value. new Car[10] is creating an array of Car with 10 elements. The special thing about instantiating arrays is that they are set to a null default value, rather than being un-initialized.

for (int i = 0; i < cars2.length; i++)
{
     cars2[i] = new Car();
}

I changed what you originally had to make things a little clear-er. the first line is the declaration of a for loop. A for loop works like this:

for( intialization_step; condition; increment_step)
{
     // commands to run while condition is true
}

Here's how it gets executed:
1. Run the intialization_step
2. Test the condition
3. If true, run the commands between the curly brackets. Else, end.
4. run the increment_step
5. Go back to 2 and continue the process

Car[] cars3 = new {new Car(), new Car(), new Car(), new Car()};

This declares the variable cars3 and instantiates it. Arrays are special because you can use the curly brackets to create an initial array in this manner.

cars1 = {new Car(), new Car(), new Car()};

Since earlier we declared we wanted to use a variable called cars1, here we are actually using it. Again, like above it instantiates cars1.

lol, i missed that last one. And no, Json. Car[] cars1 does not create a null reference. It is un-initialized, and holds no value at all (not even null!). It's true that in other programming languages (C/C++) this line would auto-initialize to null if no custom initializing is done, but Java would prefer to throw a compile error if you tried to use a variable with no value at all.