I won't be much help, since I don't know the Java libraries well.
I do own several of these sensors though and have used them in competition.
This sensor connects to an Analog input and is read using the Java equivalent of Get Voltage.
The voltage (0-5v) will need to be converted to psi if you want a human readable value. To derive the equation you can start with a series of psi readings from a pressure gauge while noting the corresponding voltage reading (just dump the raw voltage to the screen or a print). Then to calculate a best curve fit you can use the LINEST function in Excel.
For LINEST highlight two cells and SHIFT/CTRL+ENTER to get both the slope and the y-intercept.
psi = analog_reading *slope + y-intercept
The sensors have slight reading differences between them, but we used the following for our robot this past season:
psi = voltage *29.5433-10.4115 (this was for a different model, so the numbers will be different)