CoordinateArray coordinateArray, coordinateArray1, coordinateArray2;
FileCopy fileCopy, fileCopy1, fileCopy2;
CoordinateArray c_arr, c_arr_1, c_arr_2;
FileCopy f_copy, f_copy_1, f_copy_2;
Readability and camelCase are the conventions in Java.
from the official docs:
Except for variables, all instance, class, and class constants are in mixed case with a lowercase first letter. Internal words start with capital letters. Variable names should not start with underscore _ or dollar sign $ characters, even though both are allowed.
Variable names should be short yet meaningful. The choice of a variable name should be mnemonic- that is, designed to indicate to the casual observer the intent of its use. One-character variable names should be avoided except for temporary "throwaway" variables. Common names for temporary variables are i, j, k, m, and n for integers; c, d, and e for characters.
Here's a link to an archived version of Oracles naming conventions: http://www.oracle.com/technetwork/java/codeconventions-135099.html