Q:

Forced to add JRE System Library to android project

On one machine my android library builds and runs fine.  On another, with identical build path it would not build until I added JRE System Runtime. 
Why might this be? 

A:

The solution should be somewhere in these :

Make sure both the jre library paths for the machines are identical. 
And with that you should also see if the android sdk is placed
identical to the other machine
And machines should be having same OS's 32 bit or 64 bit

