How to merge multiple arrays into one?

Question

I should write a method that returns all cousins of the Person as an array of Person objects. A Person object has mother, father, children[] etc. as its instance variables and I should use this method to find all siblings of a Person's uncles and aunts then their children.

    public Person[] allSiblings(){
        int a = this.mother.children.length - 1;
        Person[] siblings = new Person[a];
        for(i=0; i<siblings.length; i++){
            if(this.mother.children[i] == this)
                continue;
            else{
                siblings[i] = this.mother.children[i];
                }
        }
        return siblings;
    }

So how can I merge these children arrays and return as one Person array in allCousins() method. I know it would be easier to use ArrayList but we are not allowed.

Thanks in advance.

Answer 1

Have a look at How can I concatenate two arrays in Java? There are some methods on how to do that. The trick is to either use a ready made function (which you probably are not allowed if Lists are forbidden) or to create a new Array with the sum of the two original Arrays as length.

Answer 2

The link mentioned by JoshOvi is good one. If you want to create your own implementation, consider ArrayUtils as reference -

public Object[] mergeArray(final Object[] arr1, final Object[] arr2) {
    if (arr1 == null) {
        return clone(arr2);
    }
    else if (arr2 == null) {
        return clone(arr1);
    }

    Object[] mergedArray = new Object[arr1.length+arr2.length];
    System.arraycopy(arr1, 0, mergedArray, 0, arr1.length);
    System.arraycopy(arr2, 0, mergedArray, arr1.length, arr2.length);
    return mergedArray;
}

public Object[] clone(Object[] array) {
    if (array == null) {
        return null;
    }
    return (Object[]) array.clone();
}