how to initialize array in java??

[abhilashm86]

i was just started with java, here in player class, i want to initialize play integer variable a, so i tried different ways to pass arguements to initialize array,
so how to do initialize??

public class play {
int a[];
int display(int size)
{
for(int i=0;i<size;i++)
System.out.println(+a[i]);
}
}

class player {
public static void main(String args[]) {
play abc=new play();
abc.a={1,2,3,4,5,6,7,8,9,10}; // upto 10
abc.display(10);

}
}
which is easiest method to initialize by passing array?

[Zugzwang]

Your question is hard to understand, maybe you are searching for something like the "arraycopy" function?

http://java.sun.com/j2se/1.4.2/docs/api/java/lang/System.html#arraycopy(java.lang.Object,%20int,%20j ava.lang.Object,%20int,%20int

Also, for such fundamental questions, consider diving into the Java Tutorials (http://java.sun.com/docs/books/tutorial/) for answers.

[abhilashm86]

should we really use copyarray?? Well in c++ and c, we can pass it through functions right,
so is it hard to pass values between classes, is there any other method to initialize??

[Ariel David Moya Sequeira]

As far as I understood the original question, you want to initialize a "play" object with "a" equal to the array {1, 2, ..., 10} (called from "player").

First of all, you need a constructor for "play". This is achieved by declaring a method named exactly as the class:

public class play {
private int[] a;

public play(int[] anArray) {

}
}

After that, you can assign "anArray" to "a" inside the constructor:

public class play {
private int[] a;

public play(int[] anArray) {
a = anArray;
}
}

Finally, you can type down the rest of the class methods. The "display" method can return void if it doesn't need to return anything (like when you want to print something). Also, you can get the array's size by using the length attribute of the array:

public class play {
private int[] a;

public play(int[] anArray) {
a = anArray; // Initialized by reference
}

public void display() {
for (int index = 0; index < a.length; index++) {
System.out.println(a[index])
}
}

}

To make a new "play" object, you just have to use:

play abc = new play({0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10});

If the above code doesn't work, then try:

play abc = new play( (int[]) {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10} );

[abhilashm86]

To make a new "play" object, you just have to use:

play abc = new play({0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10});

If the above code doesn't work, then try:

play abc = new play( (int[]) {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10} );

yes thanks a lot, well both the arrays we passed is not recieved by class, the error says,
play abc = new play({0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10});
cannot convert int to play(class)
play abc = new play( (int[]) {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10} );
constructor play(int[],int ,int.......)is undefined

so maybe its better to use copyarray, i'll try and see

[Ariel David Moya Sequeira]

If that didn't work, then I'd try using:

int[] anArray = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
play abc = new play(anArray);
Sorry, I'm working in something else right now, so I don't have a chance to test the examples I give right now. Add the fact I never used the direct initialization of an array before, so this question made me investigate a little bit; thanks for posting!

[abhilashm86]

If that didn't work, then I'd try using:

int[] anArray = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
play abc = new play(anArray);
Sorry, I'm working in something else right now, so I don't have a chance to test the examples I give right now. Add the fact I never used the direct initialization of an array before, so this question made me investigate a little bit; thanks for posting!

this is so meaning full :) it worked, thanks a lot............

[pbrockway2]

OP: The approach you took originally is workable - but you need to create the int array properly. (Depending on context, though, using an explicit constructor may well be better)

Here's a variation with nit-picky comments.



// start class names with a capital
public class Play {
int a[];
// (a) the method must have a return type void
// since it doesn't return anything
// (b) keep the brace style consistenet
void display(int size) {
// use braces
for(int i=0;i<size;i++) {
// a[i] *is* +a[i]
// + in this context means "positive", not "concatenate"
System.out.println(a[i]);
}
}
}

// start class names with a capital
class Player {
public static void main(String args[]) {
Play abc = new Play();
// abc.a must use "new" to create an int array
abc.a = new int[] {1,2,3,4,5,6,7,8,9,10};
abc.display(10);
}
}


Check out "Creating, Initializing, and Accessing an Array" in Sun's Tutorial (http://java.sun.com/docs/books/tutorial/java/nutsandbolts/arrays.html).

[jespdj]

Instead of this:

abc.a={1,2,3,4,5,6,7,8,9,10}; // upto 10
Do this:

abc.a = new int[] {1,2,3,4,5,6,7,8,9,10}; // upto 10

[abhilashm86]

Instead of this:

abc.a={1,2,3,4,5,6,7,8,9,10}; // upto 10
Do this:

abc.a = new int[] {1,2,3,4,5,6,7,8,9,10}; // upto 10

well i tried this initially, but it gives an error


abhilash@abhilash:~$ javac j12.java
j12.java:19: variable abc might not have been initialized
abc.a =new int[] {0,1,2,3,4,5,6};
^
1 error

so there is a compulsory to create a constructor(zero or parametarized) in order to initialize.........