I installed Android Studio but it was giving me error that I need to install JDK but JDK was already installed. Then I realized it is asking to install 64bit version of JDK.
I had exactly the same problem. In my case I finally installed JRE to "C:\Program Files..." and the JDK to my default destination , which is "E:\Program Files..." It seems that the JDK and JRE cannot point to the same place for Android Studio .
I had the same error -- tools.jar seems to be not in Studio classpath. Please ensure JAVA_HOME points to JDK rather than JRE.
I have a few Java JDKs downloaded. JAVA_HOME was pointing to C:\java\jdk1.7.0_45. When I switched to C:\java\jdk1.7.0_75, it worked. It makes no sense - both have lib/tools.jar. I did a jar tvf on each of the tools.jar files and they were fine. I ran java -version on each java & it ran ok. Dunno - makes no sense.
Platform: Windows 7 Professional - 64-bit v1.10.00.AG B11 Service Pack 1
I tried everything I could but it didn't help. So I reinstalled Windows and installed Android Studio and now everything works.
And the irony is, there is no JAVA_HOME or JDK_HOME variable defined but it still works.
Installing it to the default installation path instead of a custom one did solve the issue for me.
Source: https://code.google.com/p/android/issues/detail?id=187048#c9