Can we release memory variables in java and create them again?

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I am reading data from a file to an array.

The subscript of array are different, depending on the
input. Only one table is to remain in memory at any time. I
am using the same array for reading it to make the program
easy to understand, and to save on memory.

Can I release the previous array just before creating a new
array to read next entry from the file?

how?