Passing and Getting array as parameter to a function in java

Question

Can anyone help me with returning array from a function X(). I want to pass that array to a function Y() as parameter in same class.

What I have:

int[] create()throws IOException {
    System.out.println("Enter Size of Array");
    BufferedReader b=new BufferedReader(new InputStreamReader(System.in)); 
    n=Integer.parseInt(b.readLine());
    //A=new int[n];
    System.out.println("Enter Array"); for(i=0;i<n;i++) {
        int y=Integer.parseInt(b.readLine());
        A[i]=y;
    }
    return A;
}

void getarray() {
}

Do you have some code to share? I do not really understand what you mean, just creating a method with a parameter of type array? — home
– home, Commented Jan 26, 2012 at 13:46
int[] create()throws IOException { System.out.println("Enter Size of Array"); BufferedReader b=new BufferedReader(new InputStreamReader(System.in)); n=Integer.parseInt(b.readLine()); //A=new int[n]; System.out.println("Enter Array"); for(i=0;i<n;i++) { int y=Integer.parseInt(b.readLine()); A[i]=y;} return A; } void getarray() { } } — user1171354
– user1171354, Commented Jan 26, 2012 at 13:48

aioobe · Accepted Answer · 2012-01-26 14:18:55Z

5

You can store the argument to X() in a member variable, and then access the array through the member variable in Y().

class YourClass {

    private int[] someArray;

    public void X(int[] argArray) {
        someArray = argArray;         // save it like this
        ...
    }

    public void Y() {
        ...
        someArray[3] = 2;             // access it here
    }
}

Note that if you may want to consider storing such temporary variables in a ThreadLocal<int[]> if you want to be thread safe.

Regarding the update: If A is a member variable, you can access A in getarray(), either by just referring to A or, this.A if it is shadowed by some local variable.

edited Jan 26, 2012 at 14:18

answered Jan 26, 2012 at 13:44

aioobe

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6 Comments

hvgotcodes Over a year ago

+1 for mentioning ThreadLocal when the question is 'how do i pass an array to a function'. I lol'd ;)

aioobe Over a year ago

Hahaha, I know! But I've noticed that an answer to a complete noob-question, that still educates an average programmer a little, usually earns a couple of extra votes :D

hvgotcodes Over a year ago

that might be true, but for me, i actually involuntarily laughed when i saw it. So upvote for laughs, not education

aioobe Over a year ago

Hehe. Obviously. I know you're one of the Java-pros around here :)

user1171354 Over a year ago

One day i will become d best java programmer -.-". Then u will cal me pro :|

|

hvgotcodes · Accepted Answer · 2012-01-26 13:45:14Z

1

You pass an array into a method by declaring the method

public void myMethod(int[] ary);

and then, if you have an instance of an object, you do

int[] myAry = new int[9];
obj.myMethod(myArray);

now if your myMethod is calling your second method, it can just pass the reference to the array to the second method, which needs to accept an array argument. If not, then you need to store the array in a member field in your class.

class MyClass {
    int[] tmp;

    public void myMethod(int[] ary) {
        this.tmp = ary;
    }

    public void myMethod2(){
        // can use this.tmp, which will be null if it isn't set.
    }


}

answered Jan 26, 2012 at 13:45

hvgotcodes

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2 Comments

user1171354 Over a year ago

? =ob.array(); where array() is returning the array..How to store d value in ?

hvgotcodes Over a year ago

I don't understand you. To create an array of ints simply do int[] myArray = new int[10];

Tudor · Accepted Answer · 2012-01-26 13:46:05Z

1

To pass an array as parameter to a method you can use:

public void X(int[] array) {
}

If you want to access an array from two different methods of the same class, you can make the array a member of the class:

public class MyClass {
    int[] array = new int[10];

    public void X() {
    }

    public void Y() {
    }
}

Now both X and Y can access the array.

answered Jan 26, 2012 at 13:46

Tudor

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Comments

Aravind Yarram · Accepted Answer · 2012-01-26 13:46:55Z

0

class Z
{
  private int a[];

  public void x(int input [])
  {
     a=input.clone();//store input values in 'a' safely
  }

  public void y()
  {
   //work with a [] here
   System.out.println(a[0]);
   }
}

answered Jan 26, 2012 at 13:46

Aravind Yarram

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Comments

fireshadow52 · Accepted Answer · 2012-01-26 14:01:44Z

0

You can pass anything to a method, arrays included. All you have to do is add the square brackets [] after the object or simple variable type (e.g. int[] input, char[] input, JTree[] trees, etc. etc.)

public void X(int[] input) {
    //do stuff with 'input'
    Y(input);
}

public void Y(int[] input) {
    //do stuff with 'input'
}

Note that the method Y accepts an array of the simple variable type int. If it didn't, you would have to store the array in a member field in your class in order to use your array in the Y method.

edited Jan 26, 2012 at 14:01

answered Jan 26, 2012 at 13:56

fireshadow52

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