I Disassembled my APK using apktool. I encrypted all of the constant strings in smali files. After that, I tried to reassemble the app using apktool, but it is showing an exception:
Exception in thread "main" brut.androlib.AndrolibException: Could not smali file: java.io.FileInputStream@349471
at brut.androlib.src.DexFileBuilder.addSmaliFile(DexFileBuilder.java:45)
at brut.androlib.src.DexFileBuilder.addSmaliFile(DexFileBuilder.java:33)
at brut.androlib.src.SmaliBuilder.buildFile(SmaliBuilder.java:64)
at brut.androlib.src.SmaliBuilder.build(SmaliBuilder.java:48)
at brut.androlib.src.SmaliBuilder.build(SmaliBuilder.java:35)
at brut.androlib.Androlib.buildSourcesSmali(Androlib.java:222)
at brut.androlib.Androlib.buildSources(Androlib.java:179)
at brut.androlib.Androlib.build(Androlib.java:170)
at brut.androlib.Androlib.build(Androlib.java:154)
at brut.apktool.Main.cmdBuild(Main.java:182)
at brut.apktool.Main.main(Main.java:67)