Getting 2D Array of Objects to Randomly Scale

[kll]

starArray[i][j]= new Star(i *10, j* 10);

you want random try random
https://processing.org/reference/random_.html

starArray[i][j]= new Star( random(0,width), random(0,height) );

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or did you mean the array size ( number of stars ) need to be random?