The Big Programming Thread - Page 680

On November 22 2015 09:39 Acrofales wrote:
Better to see interfaces as Java's slightly quirky way of dealing with multiple inheritance. It's not wrong what you're saying, but it's a rather dry statement of the definition that doesn't show an understanding of what what the purpose of Interfaces are in Java and what their intended use is.

Interfaces are, quite literally, ways to standardize how to interface with your objects. Other classes can now be written without knowing anything about that object, except that it implements the needed Interface. Just as the user interface abstracts away the nasty details of your program, so does an Interface abstract away from the nasty details of your object.

There is no simple prefixing scheme in which an interface's methods are displayed at fixed offsets within every class that implements that interface. Instead, in the general (non-monomorphic) case, an assembly-coded stub routine must fetch a list of implemented interfaces from the receiver's InstanceKlass, and walk that list seeking the current target interface.

Once that interface is found (within the receiver's InstanceKlass), things get a little easier, because the interface's methods are arranged in an itable, or "interface method table", a display of methods whose slot structure is the same for every class that implements the interface in question. Therefore, once the interface is found within the receiver's InstanceKlass, an associated offset directs the assembly stub to an itable embedded in the InstanceKlass (just after the vtable, as one might expect). At that point, invocation proceeds as with virtual method calls.

On November 22 2015 09:39 Acrofales wrote:
Better to see interfaces as Java's slightly quirky way of dealing with multiple inheritance. It's not wrong what you're saying, but it's a rather dry statement of the definition that doesn't show an understanding of what what the purpose of Interfaces are in Java and what their intended use is.

Interfaces are, quite literally, ways to standardize how to interface with your objects. Other classes can now be written without knowing anything about that object, except that it implements the needed Interface. Just as the user interface abstracts away the nasty details of your program, so does an Interface abstract away from the nasty details of your object.

On November 23 2015 00:23 travis wrote:
Okay, so a string is already an array, yeah?

So when my comp sci class asks me to write a 2 dimensional string array, is that really just a 3 dimensional character array?

(like, I won't write it that way - but that's what it really is?)


Why am I having to put that in braces???

On November 23 2015 01:45 travis wrote:
ah ok, it looks like it's not necessary in main but outside of main it is

On November 23 2015 04:34 Housemd wrote:
It compiles but I'm not entirely sure if it works 100% and since I don't really have anything to test it on, could someone who knows more than me check if it will work as intended?

On November 23 2015 03:04 Blisse wrote:
The problem isn't your code, it's where you're putting them. Damn this will be hard to explain over the Internet...

All of your stringArray stuff is being declared as member variables, which is invalid.

You have a class ewt that has a member variable stringArray and function returnedArray. Those are legal declarations for classes. But stringArray[0][1] = "hello" is an assignment, and that isn't a legal declaration (or a declaration at all). Assignments are only valid inside functionsmethods (like main).

Someone else can explain this better because I'm at a loss at explaining this better (not in position to write/post code).

public class ewt {

    private String[][] stringArray;

    public ewt(String a, String b, String c, String d) {
        this.stringArray = new String[2][2];
        this.stringArray[0][0] = a;
        this.stringArray[0][1] = b;
        this.stringArray[1][0] = c;
        this.stringArray[1][1] = d;
    }
}

On November 23 2015 03:04 Blisse wrote:
The problem isn't your code, it's where you're putting them. Damn this will be hard to explain over the Internet...

All of your stringArray stuff is being declared as member variables, which is invalid.

You have a class ewt that has a member variable stringArray and function returnedArray. Those are legal declarations for classes. But stringArray[0][1] = "hello" is an assignment, and that isn't a legal declaration (or a declaration at all). Assignments are only valid inside functions (like main).

Someone else can explain this better because I'm at a loss at explaining this better (not in position to write/post code).

String [][] stringArray = {
  {'hello', 'hallo'},
  {'hullo', 'hyllo'}
}