Thread: Calling up array methods from main

I'm having trouble just calling up the methods from main. I just need to test them to see if they work.

public static void main(String[] args) {
        // TODO code application logic here
    }
 
    public static int randomInt(int low, int high) {
	int difference = high - low;
	return (int)(Math.random()*(difference + 1)) + low;
	}
 
    public static int[] randomIntArray (int n, int low, int high) {
        int[] a = new int[n];
        for (int i = 0; i<a.length; i++) {
        a[i] = randomInt (low, high);
    }
    return a;
  }
 
    public static int indexOfMaxInRange(int[] arr, int lowIndex, int highIndex) {
	int indexOfMax = lowIndex;
 
	for (int i = lowIndex+1; i <= highIndex; i++) {
		if (arr[i] > arr[indexOfMax]) {
			indexOfMax = i;
			}
		}
		return indexOfMax; 
	}
 
    public static void swapElement(int[] arr, int index1, int index2) {
	int temp = arr[index1];
	arr[index1] = arr[index2];
	arr[index2] = temp; 
	}
 
    public static void sort(int[] arr) {
	int length = arr.length;
		//use length-1 because do not need to swap last element with itself
	for (int i = 0; i < length-1; i++) {
		int indexOfMax = indexOfMaxInRange(arr, i, length-1);
		swapElement(arr, i, indexOfMax); 
		}
	}	
}

Since all the methods are static, you just need to call them without creating an instance of the class and make sure you assign a variable that is of the same data type as the return (for your non-void return methods only).

I still don't understand what you mean. Could you provide me with an example?

Could you provide me with an example?

An example of calling a method?!

I don't mean to mock you. But read your textbook, notes, or any other source of Java code you have available and give it a go. It doesn't matter at all if the compiler complains about what you try. That's where we all started! Post the code you are trying and the compiler messages as Norm suggests.

I'm having problems outputting or testing the methods by main.

public static void main(String[] args) {
 
    }
public static int randomInt(int low, int high) {
	int difference = high - low;
	return (int)(Math.random()*(difference + 1)) + low;
	}
 
    public static int[] randomIntArray (int n, int low, int high) {
        int[] a = new int[n];
        for (int i = 0; i<a.length; i++) {
        a[i] = randomInt (low, high);
    }
    return a;
  }
 
  public static int indexOfMaxInRange(int[] arr, int lowIndex, int highIndex) {
	int indexOfMax = lowIndex;
 
	for (int i = lowIndex+1; i <= highIndex; i++) {
		if (arr[i] > arr[indexOfMax]) {
			indexOfMax = i;
			}
		}
		return indexOfMax; 
	}
 
    public static void swapElement(int[] arr, int index1, int index2) {
	int temp = arr[index1];
	arr[index1] = arr[index2];
	arr[index2] = temp; 
	}
 
    public static void sort(int[] arr) {
	int length = arr.length;
	for (int i = 0; i < length-1; i++) {
		int indexOfMax = indexOfMaxInRange(arr, i, length-1);
		swapElement(arr, i, indexOfMax); 
		}
	}

Well, how do you call a method? From just a quick overview I can say those are some nice looking methods. All your methods have the parameters that are passed in already written in their headers, so in your main you have to call those methods and pass in the appropiate variables. Just do one at a time and make sure each one works before going to the next one.

Originally Posted by my21

I still don't understand what you mean. Could you provide me with an example?

No offence but, how is it you can write your own methods, use static, return statements and single-dimension arrays, yet don't know how to call them? Use whatever source(s) you're studying or learning from to see examples.

I got it! Thanks for your help!

Re: Calling up array methods from main
Try this with some of your own effort...

public static void main(String[] args) {
int rndInt = randomInt(int low, int high);
int arr[]= randomIntArray (int n, int low, int high);
int MaxRange = indexOfMaxInRange(randomIntArray (int n, int low, int high), int lowIndex, int highIndex);
System.out.println( sort(randomIntArray (int n, int low, int high)) );
}

Thank you norm, i am new with the forums. Thank you i will take care of it in future.