How can I convert file size human-readable format into byte size in Java?

Question

I basically need to do the opposite of this: How can I convert byte size into a human-readable format in Java?
Input: 10.0MB
Outpt: 10000000

Answer 1

Based on HariHaravelan's answer

public enum Unit {
    B(1), KB(1024), MB(1024*1024), GB((1024L*1024L*1024L)
    ;
    private final long multiplier;

    private Unit(long multiplier) {
        this.multiplier = multiplier;
    }
    
    // IllegalArgumentException if the symbol is not recognized
    public static long multiplier(String symbol) throws IllegalArgumentException {
        return Unit.valueOf(symbol.toUpperCase()).multiplier;
    }
}

to be used as in
long bytes = (long) (10.0 * Unit.multiplier("MB"))

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for scientific units (KB = 1000), replace first line inside the enum (underscore between digits are ignored by Java):

public enum Unit {
    B(1), KB(1_000), MB(1_000_000), GB((1_000_000_000)
    ... rest as above

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More units can be added as needed - up to the limit of long, if more are required, the multiplier declaration can be changed to BigDecimal or double according use case/requirement.