Static String Return Type

[Java_Developer]

Hello,

I have an array interface and I should write the methods for them,I have a question in the following method.
I should write a method String toString(int[] arr) that returns a string which, if printed, provides a niprint out of the array content. Used as:
int n = {3,4,5,6,7};
String str = Arrays.toString(n);
System.out.println("n = " + str);

I have written my method like this :

static String toString(int[] arr)
	{
		System.out.print("\n"+ "All the values in the array are: " );
		int i;
		String array = null;
		for ( i = 0; i < arr.length; i++ ) 
		{
			array=Integer.toString(arr[i]);
			System.out.print(" "+ array);
		}
		return " "+ array;
	}

& the return type return NULL !I would like to know what I can I call as a return type.

Thanks all in advance.

[r035198x]

Di you call the method with array that has values.

[Java_Developer]

Yes Actually Like this
int[] array = new int[] {1,2,3,10,5};
Arrays.toString(array);

& It prints :
All the values in the array are: 1 2 3 10 5
Which is correct but It's the System.out.println that shows this line if I remove it wont show anything I mean the return " "+ array; won't return anything !

[masijade]

You do realise that this

array=Integer.toString(arr[i]);

results in only the last element being "saved" in the String, right?

[Java_Developer]

Yes you are right!But I couldn't find a better way to implement that method.

[r035198x]

..
Which is correct but It's the System.out.println that shows this line if I remove it wont show anything I mean the return " "+ array; won't return anything !

The println won't change the value that is returned by the method.

[masijade]

Yes you are right!But I couldn't find a better way to implement that method.

+= maybe?

[Java_Developer]

& then I will get the following return type which is totally wrong :

All the values in the array are: null1 null12 null123 null12310 null123105

[masijade]

String array = "";
...
array += " " + Integ....
System.out.println(array);//this is obviously only debug

[Java_Developer]

You mean like this:

static String toString(int[] arr)
	{
		System.out.print("\n"+ "All the values in the array are: " );
		int i;
		String array = "";
		for ( i = 0; i < arr.length; i++ ) 
		{
			array+=" " + Integer.toString(arr[i]);
			
		}
		return array;

But still array won't return anything :(

[masijade]

Show the "calling" code. You probably doing something wrong outside of this method.

[Java_Developer]

The calling code is simple one :

int[] array = new int[] {1,2,3,10,5};
Arrays.toString(array);

[masijade]

That has nothing to do with the method you just wrote, and you are not storing the result of that anywhere.

[Java_Developer]

Yes and the test is like :
String test=Arrays.toString(array);
System.out.print(test);

and it will show the last element in the array just 5 !

[r035198x]

Read Masi's reply #9 above again.

[masijade]

So, you've written your own class Arrays? You do know that there is already an Arrays class, right?

[Java_Developer]

Yes I know and then testing this class with Junit .

[Java_Developer]

Thanks for helping me,the problem solved now :)