Various methods to disassemble dex files -
This how-to documents various methods and tools in disassembling DEX files for the Android OS. An example "Hello Android" APK file developed from the Android SDK example is used to demonstrate the various tools. The various tools and methods are listed below in the subsections.
Tools
The HelloAndroid.apk package was decompressed using a standard zip-utility. The output from the zip utility produced the following files:
$unzip HelloAndroid.apk Archive: HelloAndroid.apk inflating: res/layout/main.xml inflating: AndroidManifest.xml extracting: resources.arsc extracting: res/drawable-hdpi/icon.png extracting: res/drawable-ldpi/icon.png extracting: res/drawable-mdpi/icon.png inflating: classes.dex 
The file of importance in analyzing the various methods of disassembly is 'classes.dex'. The various tools listed below will use this file.
dedexer
A disassembler (available at https://dedexer.sourceforge.net/) to turn the DEX format into an "assembly-like format". The format uses Jasmin like syntax and various Dalvik opcodes. The command used to disassemble the classes.dex file is:
$ java -jar ddx1.11.jar -d HelloAndroidOoutput classes.dex Processing com/example/helloandroid/HelloAndroid Processing com/example/helloandroid/R$attr Processing com/example/helloandroid/R$drawable Processing com/example/helloandroid/R$layout Processing com/example/helloandroid/R$string Processing com/example/helloandroid/R 
The command produced several files, but the important file is located at com/example/helloandroid/HelloAndroid. The disassembly listing for that file is below.
$ cat com/example/helloandroid/HelloAndroid.ddx .class public com/example/helloandroid/HelloAndroid .super android/app/Activity .source HelloAndroid.java .method public <init>()V .limit registers 1 ; this: v0 (Lcom/example/helloandroid/HelloAndroid;) .line 7 invoke-direct {v0},android/app/Activity/<init> ; <init>()V return-void .end method .method public onCreate(Landroid/os/Bundle;)V .limit registers 4 ; this: v2 (Lcom/example/helloandroid/HelloAndroid;) ; parameter[0] : v3 (Landroid/os/Bundle;) .line 11 invoke-super {v2,v3},android/app/Activity/onCreate ; onCreate(Landroid/os/Bundle;)V .line 12 new-instance v0,android/widget/TextView invoke-direct {v0,v2},android/widget/TextView/<init> ; <init>(Landroid/content/Context;)V .line 13 const-string v1,"Hello, Android" invoke-virtual {v0,v1},android/widget/TextView/setText ; setText(Ljava/lang/CharSequence;)V .line 14 invoke-virtual {v2,v0},com/example/helloandroid/HelloAndroid/setContentView ; setContentView(Landroid/view/View;)V .line 15 return-void .end method 
baksmali
The baksmali disassembler (available at https://code.google.com/archive/p/smali) disassembles the DEX file into a format loosely based on the Jasmin's/dedexer's syntax. The command used in this analysis to generate the disassembly is:
$ java -jar baksmali-1.2.4.jar classes.dex 
The command outputs several files and produces the /out/com/example/helloandroid directory structure, but the main file to investigate is HelloAndroid.smali. HelloAndroid.smali displays the Jasmin syntax and partial Dalvik opcodes as:
.class public Lcom/example/helloandroid/HelloAndroid; .super Landroid/app/Activity; .source "HelloAndroid.java" # direct methods .method public constructor <init>()V .registers 1 .prologue .line 7 invoke-direct {p0}, Landroid/app/Activity;-><init>()V return-void .end method # virtual methods .method public onCreate(Landroid/os/Bundle;)V .registers 4 .parameter "savedInstanceState" .prologue .line 11 invoke-super {p0, p1}, Landroid/app/Activity;->onCreate(Landroid/os/Bundle;)V .line 12 new-instance v0, Landroid/widget/TextView; invoke-direct {v0, p0}, Landroid/widget/TextView;-><init>(Landroid/content/Context;)V .line 13 .local v0, tv:Landroid/widget/TextView; const-string v1, "Hello, Android" invoke-virtual {v0, v1}, Landroid/widget/TextView;->setText(Ljava/lang/CharSequence;)V .line 14 invoke-virtual {p0, v0}, Lcom/example/helloandroid/HelloAndroid;->setContentView(Landroid/view/View;)V .line 15 return-void .end method 
dex2jar
An easier method for disassembling DEX files is to reproduce the Java files. The procedure for performing this task is to take the Dalvik opcodes to the Java byte codes (JAR file). The next step is to take a Java decompiler, which will produce several java files. The two tools used in the section are dex2jar (available at https://github.com/pxb1988/dex2jar) and a java decompiler of choice. The steps performed to complete this transformation are:
$ ./dex2jar.bat classes.dex
Load the produced JAR file from dex2jar into the java decompiler.
The main class produced from the decompilation process using dex2jar is listed below.
package com.example.helloandroid; import android.app.Activity; import android.os.Bundle; import android.widget.TextView; public class HelloAndroid extends Activity { public void onCreate(Bundle paramBundle) { super.onCreate(paramBundle); TextView localTextView = new TextView(this); localTextView.setText("Hello, Android"); setContentView(localTextView); } }