what is this error im ImageIO class in java (android)?

the error is :

02-22 22:58:11.208: ERROR/AndroidRuntime(498): FATAL EXCEPTION: main
02-22 22:58:11.208: ERROR/AndroidRuntime(498): java.lang.NoClassDefFoundError: javax.imageio.ImageIO
02-22 22:58:11.208: ERROR/AndroidRuntime(498):     at aynoo.forms.FreindMessagesActivity.convertInputStreamToString(FreindMessagesActi开发者_StackOverflowvity.java:493)
02-22 22:58:11.208: ERROR/AndroidRuntime(498):     at aynoo.forms.FreindMessagesA

That class isn't provided by the Dalvik JVM. Here is the list of packages the Android SDK includes:

http://developer.android.com/reference/packages.html