How to make an array from a method not change each time the method is called

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I made a method that uses the random class to generate a number. These numbers are used to fill in an array. This method returns the filled in array. So, I have a few other arrays that I made which are equal to the returned array. However, these arrays are all the same even though they should be random.

I tried printing how each array that calls the random, right under where it calls. This gave me different arrays. But if I move my prints to under all the calls then the arrays are all the same. Also I think this is an array issue because I only have this problem with arrays.

    public static int[] numberGenerator(int[] array) {
        Random rand = new Random();
        int min = 0;
        int max = 0;
        int x = 0;

        for (int j = 0; j < array.length; j++) {        

            if (j == 0) {
                min = 1;
                max = 15;
            }
            if (j == 1) {
                min = 16;
                max = 30;
            }
            if (j == 2) {
                min = 31;
                max = 45;
            }
            x = rand.nextInt((max - min) + 1) + min;
            array[j] = x;                               
        }
        return array;
    }

    public static void main(String[] args) {
        int[] array = {' ', ' ', ' '};
        int[] array1 = numberGenerator(array);  
        int[] array2 = numberGenerator(array);

        System.out.println(array1[1]);
        System.out.println(array2[1]);          
    }
}

Distinct arrays are what I'm looking for.

You're modifying the array that you pass into the method. Given that you don't use the existing content of the array anyway, it would be better to just pass in the length that you want, and create a new array in the method:

public static int[] numberGenerator(int length) {
    int[] array = new int[length];
    // Rest of method as before
}

Then change your main method to:

public static void main(String[] args) {
    int[] array1 = numberGenerator(3);  
    int[] array2 = numberGenerator(3);

    System.out.println(array1[1]);
    System.out.println(array2[1]);          
}

How to Return an Array in Java, Search the array for an element and returns its position To reuse the same array create it ouside the method and pass the same instance at every call. – Andrea Polci Apr 4 '10 at 8:44 @Troy: If that's the case, you may want to make the array static (just make sure to set every index each time through, because old values will still be there).

You have to understand how pass by reference and pass by value work in Java. Arrays are considered as objects, and they get passed into methods by reference. This means, in your code there is only one physical array array and that is getting passed along, and all the modifications are being done on it.

You can follow any of the designs suggested by other answers to solve your problem!

How to pass Arrays to Methods in Java?, Returns a Array Iteration Object, containing the keys of the original array The every() method checks if all elements in an array pass a test (provided as a function). The every() method executes the function once for each element present in the array: If it finds an array element where the function returns a false value, every() returns false (and does not check the remaining values) If no false occur, every() returns

You are passing the same array object to the two calls to numberGenerator, so of course they return the same array (since numberGenerator doesn't create a new array, it just fills the array you pass to it).

You can pass a different array in each call:

int[] array1 = numberGenerator(new int[3]);  
int[] array2 = numberGenerator(new int[3]);

Or, as an alternative, pass an array length to numberGenerator, and let that method create the array:

public static int[] numberGenerator(int length) {
    int[] array = new int[length];

    ... fill the array ...

    return array;
}

and use it with:

int[] array1 = numberGenerator(3);  
int[] array2 = numberGenerator(5);

JavaScript Array Reference, Are the array's elements copied when an array is passed to a method? A node list is not an array, but an enumeration object, containing each of the matched elements. This means the Array.forEach method is not available. The node list object does have a forEach method that functions the exact same as the Array forEach method.

Don't use the passed parameters to store the generated random number. You should create a new array in the method to store the random number. This is because the argument to the array type of the method is a reference. The array you return is actually a reference to this array. The value of this array depends on your last modification. The value of array1 above will become the last modification. This is why array1 is the same as array 2 because they all point to an array.

public static int[] numberGenerator(int[] array) {
    Random rand = new Random();
    int min = 0;
    int max = 0;
    int x = 0;
    int[] newArray = new int[array.length];
    for (int j = 0; j < array.length; j++) {

        if (j == 0) {
            min = 1;
            max = 15;
        }
        if (j == 1) {
            min = 16;
            max = 30;
        }
        if (j == 2) {
            min = 31;
            max = 45;
        }
        x = rand.nextInt((max - min) + 1) + min;
        newArray [j] = x;
    }
    return newArray ;
}

Are arrays passed by value or passed by reference in Java?, public static int[] returnArrayMethod() { // method code which includes creating an int array called vector2 return vector2; } As was mentioned earlier it is not possible for a method to change the value of its arguments. E.g. Note that in this particular case, since any value changes are made to data in the original area of  The each method takes two arguments—an element and a block. The element, contained within the pipes, is similar to a placeholder. Whatever you put inside the pipes is used in the block to represent each element of the array in turn. The block is the line of code that is executed on each of the array items and is handed the element to process.

Passing arrays to methods, Write code that creates an array named odds and stores all odd numbers between -6 and 38 into it using a for loop. Make the array's size exactly large enough to store the numbers. Your method should not modify the elements of the array. public static int (The order of the answer choices is randomly shuffled each time.) For a method to return an array the method should be declared as you might expect: public static int[] returnArrayMethod() { // method code which includes creating an int array called vector2 return vector2; } When a primitive data type, e.g. double, is passed to a method, its value is copied to the new method variable.

JAVA = ARRAYS Flashcards, With implementation hiding, you make a request to a method without knowing the the reservation method—you still call and provide your name, a date, and a time. that a method that calls another must know the name of the called method​, not change, you won't need to make any changes in any methods that call the​  Write a method called allLess that accepts two arrays of integers and returns true if each element in the first array is less than the element at the same index in the second array. Your method should return false if the arrays are not the same length. For example, if the two arrays passed are {45, 20, 300} and {50, 41, 600}, your method should

An Object-Oriented Approach to Programming Logic and Design, The splice method is also able to insert the elements without any removals. let arr = [ 1 , 2 ] ; // create an array from: arr and [3,4] alert ( arr . concat ( [ 3 , 4 ] ) ) ; // 1,2 The function is called for elements of the array, one after another: The call to arr.sort() sorts the array in place, changing its element order. Each time a method is invoked, the system stores parameters and local variables in an area of memory, known as _____, which stores elements in last-in first-out fashion. a stack Variables defined inside a method are called ________.

Comments
  • try adding print statements in between the method calls, see if that tells you more about where the problem lies
  • Use Debugger if you are using any IDE such as Eclipse. It will save a lot of time of yours (and stackoverflow users as well.) Happy Coding and welcome to the world of stackoverflow.
  • Maybe have a look at: Is Java "pass-by-reference" or "pass-by-value"?