yes, APK files only run on android. sis runs only on symbian, ipa only on ios. they all are programmed differently and that's why only the specific OS can handle it.
jar files, which is Java, can run on most OS, except for iOS, on a Java emulator. the Java emulator comes stock on most phones. however, you might not get full functionality on the newer phones - touch might not work and it might not be full screen. you have to check the phone specs to see if it supports Java.