Thread: Static in a non static

Hey!

The the code that i have must be able to, via a method, take an array of numbers and make them into a string and then return to print them out.
There is two parts of this code so far (two methods other than the main).

The first method adds numbers in an array and prints out the sum and it works fine.
But the second one, aka the string one, doesn't work.


Any tips?

	public static void main(String[] args) {
		// First part!
		int[] Array = { 3, 4, 5, 6, 7 };
		int hellfire = sum(Array);
		System.out.println(hellfire);
 
		// Second part...
		System.out.println(toString());
 
	}
 
//Works! 
	public static int sum(int[] Array) {
 
		int n = 0;
		for (int i : Array) {
			n += i;
		}
		return n;
	}
 
//Can't get it to do anything.. 
	public static String toString(int[] k) {
		int[] n = { 3, 4, 5, 6, 7 };
		String str = Arrays.toString(n);
		System.out.println("n = " + str);
		return str;
	}
 
}

Originally Posted by Norm

Please explain. If there are error messages, copy the full text and paste it here.


How are you calling the method? Where is the code that passes it an int array?

I get "Cannot make a static reference to the non-static method toString() from the type Object".
I thought that i could call it from "System.out.println(toString());" in the main, but i guess that is a wrong way of doing it?

This is what my task says I should be able to do.


The method String toString (int [] arr) that builds a string and it prints out the content of the array.
It should be able to be used as follows with good results:

int[] n = {3,4,5,6,7};
String str = Arrays.toString(n);
System.out.println("n = " + str);

I just don't get what i should be doing here... Maybe anyone in here knows? Becuse even when i changed it and did as you told me to do
then it just crashes.

Originally Posted by Norm

Please copy the full text of the error message and paste it here. It has important info about the error.

Those 3 lines of code in post#5 work for me.

Exception in thread "main" java.lang.StackOverflowError
at km222nb_lab3.Arrays.toString(Arrays.java)
at km222nb_lab3.Arrays.toString(Arrays.java:32)
at km222nb_lab3.Arrays.toString(Arrays.java:32)

	public static String toString(int[] k) {
		int[] n = { 3, 4, 5, 6, 7 };
		String str = Arrays.toString(n); //Says that something is going on here...
		System.out.println("n = " + str);
		return str;
	}

Originally Posted by Norm

The code is calling itself repeatedly until the callstack exceeds the available memory.

You should NOT give your class the same name (Arrays) as a java SE class: java.util.Arrays.
Change the name of your class to something else.
The Arrays class's toString method is a wellknown and used method for displaying the contents of arrays. Don't confuse things by using the same class name.

Well that's good to know however.. i am not allowed to use any of the help from the lib.
And on top of that i think that i should be able to get the info from the n array and not from the
static one, aka from the one in which the toString method exists.

Originally Posted by Norm

Sorry, I have no idea what you are asking.

Can you post the code and a description of what it is supposed to do?

Yeah.
Been altering the code much too from what they wanted from post 5.

public class arraykm {
	static int[] arr = { 3, 4, 5, 6, 7 };
 
	public static void main(String[] args) {
 
		int hellfire = sum(arr);
		System.out.println(hellfire);
 
		// The main method is here as a tester.
		// So it tests out the other static methods.
		// The second static method should be able to print
		System.out.println(toString(arr));
		//But it doesn't work.. no matter what i do. 
	}
 
	public static int sum(int[] arr) {
 
		int n = 0;
		for (int i : arr) {
			n += i;
		}
		return n;
	}
 
	public static String toString(int[] arr) {
		String str = arr.toString();
		System.out.println("n = " + str);
		return str;
	}
 
}

Well lets start back at the begining then....
I have this class that i need to make a couple of static methods, i am not allowed to use the lib.
The main method is there to act as a testprogram to show how each method can be used.
The first method is done but it is the second one that i have difficultiy with...

The second one says: Make the method String toString(int[] arr) that builds up a string and that when it prints out it prints the content
of the array. It should be used in the following way with good results:

     int[] n = {3,4,5,6,7};
     String str = Arrays.toString(n);
     System.out.println("n = " + str);

Forget about the codes above then. Lets just pretend that we have a clean main method and want to make a
new method from the info from the second question.
Any ideas of how i should make this work?

Originally Posted by Norm

What should the method return? Given this array: int[] arr = { 3, 4, 5, 6, 7 };
What should be in the String the method returns?
Post what the desired String would look like for that array.

You can not write any code Until you decide what should be in the String.

I want to get the numbers from the array without touching any lib and pass them to a string
and print them out.

Originally Posted by Norm

Please post the exact String that the method should return for this array: int[] arr = { 3, 4, 5, 6, 7 };
For example: "34567"

Once we get that we can work on how to build that String.

Lets just say this. I want a code that takes the info from an array, can be static or in main, and prints it out from its String method when we call for it.
Say take this one step at the time. And i will get to the end result when i get there because this is the best way for me to learn. Otherwise i don't..

n = 3 4 5 6 7. Thats what it should print out!

Originally Posted by Norm

Ok so the String returned by the toString method should have the elements of the array separated by a single space.
To do that write a loop that iterates though the array and concatenates each element of the array and a space to a String.
Define the String before the loop and assign it an empty String: "".

Thanks, i got it working now!
Atleast i think so haha.

	public static String tostring(int[] arr) {
		String str1 = null;
		String strk = " "; 
		for (int i = 0; i < Arr.length; i++) {
			System.out.print(Arr[i] + strk);
			str1 = Integer.toString(i);
		}
		return str1;

In main i say

	System.out.println(tostring(Arr));

And i use "Arr" as a static method alone with the numbers 34567.