You can add one or several random numbers into your array variables, but Java does not guarantee that each number is unique. Right-click the Java file you want to edit and select "Open With." ...

Listing 1. Java guarantees that an assign to an array component preserves the general dynamic type of the array. T[] x; ... x = new T’[10]; /*legal, T’[] is a subtype of T[] */ ... T’ a = new T’(); ...