Generating random numbers

Good day people,am struggling with a problem and i hope you can be of help.i want to generate 15 random interger numbers between 0-75,and none of the numbers once generated is repeated,e.g once 2,5,or 11 are generated by the subroutine or function they are not repeated again instead ,math.random() is called again to generate new intergers until new integers different from those generated are produced...hw do i do this,do i get a variable to save the generated numbers and check this value against a new generated number.
i am developing this application for j2ME so icant work with vectors or arrays.thanks