Arrays

[Mathangi Shankar]

Hi,

Please let me know in the following code at the commented line why does the compiler give error?

We are just assigning a value in the array of type int!!!

class ArrayTest {

static int [ ] intArray = new int [5] ;
static int[ ] intArray1 = new int [1] ;

// intArray1[0] = 5;
static char [ ] charArray = new char [5] ;

public static void main (String [ ] args) {
System.out.println (charArray [1] ) ;
intArray1 = intArray ;
}
}

[Sanju Thomas]

Originally posted by Mathangi Shankar:

class ArrayTest {

static int [ ] intArray = new int [5] ;
static int[ ] intArray1 = new int [1] ;

// intArray1[0] = 5;
static char [ ] charArray = new char [5] ;

public static void main (String [ ] args) {
System.out.println (charArray [1] ) ;
intArray1 = intArray ;
}
}

Please initialize it in the method.

 
class ArrayTest {
 
static int [ ] intArray = new int [5] ;
static int[ ] intArray1 = new int [1] ;
static char [ ] charArray = new char [5] ;
 
public static void main (String [ ] args) {
intArray1[0]=1;
System.out.println (charArray [1] ) ;
intArray1 = intArray ;
}
} 

[Mathangi Shankar]

Are there any more rules regarding initialization of arrays that we need to do in a local method only.

Thanks,
Mathangi

[Sanju Thomas]

You can do it in this way too.

 
 
class ArrayTest {
 
static int [ ] intArray = new int [5] ;
static int[ ] intArray1 = {1};
 
static char [ ] charArray = new char [5] ;
 
public static void main (String [ ] args) {
 
System.out.println (charArray [1] ) ;
intArray1 = intArray ;
 
}
}

Now you must have understood the rule, right ?

[levani dvalishvili]

Sanju! I have t admit that in both of your answers you are more like challenging Mathangi than actualy answering his question , I do not think tha's what he asked for,
as of your examples: as far as I see you try to explain that array needs to be initialized before asigning
but you never explained to him why?
'there is the short hand of initializing and declaring an array that is what Sanju showed on second example, that is: int[] arr = {1,2,3,}; etc... that will create array and will automaticly adjust the size of array based on how many parametes you pass to it .
See B&K book's Chapter 1 it is explained there greatly

[M Rama]

Mathangi,

The reason you got the error is because, you can only declare items outside a method, but shouldn't use other statements

for ex:

class Test {
 
 
 static int abc ;
 abc =5 ;//line 1
 

public static void main(String[] args) {

}
}

you will get an error in line 1

however in the following code:

class Test {
 
 
 static int abc = 5 ;//line 1
 

public static void main(String[] args) {

}
}

is valid.

So is the following code:

class Test {
 
 
 static int abc =5 ;
 static int xyz = abc+ 5 ;//line 1
 

public static void main(String[] args) {

}
}

[M Rama]

The following is valid as well:

class Test {
 
static int abc;
 
static {
abc = 5;
}
 
public static void main(String[] args) {
 
}
}

so, i have to rephrase my intial statement. you can declare items outside a block, but can't use other statements.

[Sanju Thomas]

Mathangi,

Declaration and initialization of instance variables and class variables as seperate statement is not legal. But you can do it in the case of member variables.

I think now you got a clear idea.
[ April 14, 2005: Message edited by: -Sanju Thomas- ]

[Mathangi Shankar]

Hi Dudes,

Thanks a lot for all your answers. Finally I got one thing clear that declaration and initialization in seperate statements is illegal.

However I one doubt in what Sanju has answered. You said that class for variables and instance variables declaration and initialization in seperate statements is illegal but for member variables it holds good.

Can you quote me an example please where member variables are used in such a case?

Thanks,

Mathangi.

[Sanju Thomas]

Sorry Mathangi, I mean local variables.

[Parameswaran Thangavel]

hi sanju
i didn't get what u mean here
can u please explain me

Declaration and initialization of instance variables and class variables as seperate statement is not legal. But you can do it in the case of member variables

[Sanju Thomas]

Declaration and initialization of instance variables and class variables as seperate statement is not legal. But you can do it in the case of member variables

Hi Parameswaran,

That one I have mistakenly written . What I mean is, Declaration and initialization of instance variables and class variables as seperate statement is not legal. But it is legal in the case of local variables.

see the example code.

 class VariableInit{
 
// this is fine
 
int var = 100; // instance variable
static int var1 =100; // class variable
 

/*

Declaration and initialization of both instance variable and class 
variables as seperate statement will produce compile time error.

// this will produce a compile time error

int x;
x=100;

static int y;
y=100;
*/
 


 
public void myMethod(){
 
// but in local variable's case, it is legal.
// you can use two statments for declaration and initialization.
 

int var ;
var =100;

// this is too valid
 
int var1 =100;
 

}
 
} 

You may clear now.

[Gjorgi Var]

Originally posted by Mathangi Shankar:
Hi,


We are just assigning a value in the array of type int!!!

class ArrayTest {

static int [ ] intArray = new int [5] ;
static int[ ] intArray1 = new int [1] ;

// intArray1[0] = 5;
static char [ ] charArray = new char [5] ;

public static void main (String [ ] args) {
System.out.println (charArray [1] ) ;
intArray1 = intArray ;
}
}

Show me where are you assigning a value of type int or of any type in any array that you've declared and constructed but not initialized.
Also, you can initialize arrays wherever you may please, it doesn't have to be in the main(). The fact that they're static only means that they can be used without instantiating the class.
As they are now, your arrays are full of default null values (for int is 0, for char is '\u0000'. If they weren't static, and were declared and constructed in main() as local, you would have real problems compiling...