Write down a complete Java program that declares an integer array, intArray, and initialize it to {1, 2, 3, 4, 5, 6, and 7}. The program must have the following methods:

1) void displayOddPositions ()

This method displays array elements in the odd positions only, named as, 2, 4, 6.

2) void displayReverse ()

This function shows the array elements in the reverse order so the last item emerges first and vice versa.

3) void multiplyByFactor (int factor)

This method multiplies all the elements within the array by a given factor.

4) void addArray(int[] givenArray)

This method is utilized to add an array to the current data field intArray. First, check that the givenArray is same length as the data field array. If they are the same length, then add each element within the givenArray to the corresponding element in intArray.

5) Write down the main method in order to test and display the functionality of the above methods.