[Android] Build & Tools (proguard etc)

1. Build from command line (use ant)
   
   • Create build.xml
     
     1. For old sdk (such 1.5)
        activitycreator --out
     2. For new sdk
        android update project -t -p
        Notes: you can run 'android list target' list all supported targets. the relationship among sdk version, api level, and target are:
        SDK Ver       API Level       Target
        1.5           3               1
        1.6           4               2
        2.1           7               3
        2.2           8               4
        
     3. xxx
        
   • Build
     Run 'ant [debug|release]' on command line to start build.
     
   • xxx
     
2. Proguard
1. Intro
   The ProGuard tool shrinks, optimizes, and obfuscates your code by removing unused code and renaming classes, fields, and methods with semantically obscure names. 
2. Docs
• http://developer.android.com/guide/developing/tools/proguard.html
• 
  
3. Command
   
   • keep
     
     1. What need to be kept
        All classes name and methodes that will be accessed out of application need to be kept, such as:
        
        • Native methods
          
        • The class name and methods that are referenced in JNI
        • The constructor of classes that will be initiated by System
          
     2. What need NOT to be kept
        
        • Methods inherit from classes defined in SDK
        • private method/fields
        • the methods/files that are only used with in app
          
     3. xxx
        
   • keepattributes
     
     1. InnerClasses
        Preserve the name of inner class, so that the inner class be referenced outside of outer class. By default, the name of inner class is OuterClass$InnerClass, while if this attribute is present, the name of inner class becomes InnerClass.
        
     2. xxx
        
   • xxx
4. FAQ
• [Question] Class members to be accessed in JNI are removed after optimized by ProGuard even if you added the following lines:
  -keep
  [Solution] Modify the line as following:
  -keep {
      ;
  }
  
  i.e. if you want to prevent helloworld.output from being removed, you need to add the following lines:
  -keep class com.helloworld {
      public void output(int, java.lang.String);
  }
  
5. Issue
   
   • java.lang.NoClassDefFoundError
     
     1. Reverse .apk
        Please refer to: http://blogold.chinaunix.net/u/9577/showart.php?id=2260443
        
     2. Check the reversed source code to see which classes and/or their methods should be preserved but actually they are obfuscated. To resolve this issue, just keep corresponding classes name and/or methods name.
        
   • Unknown Source
     App crashes on launch when built with Proguard 4.3 due to verify errors
     
     
   • xxx
     
6. xxx
   
3. xxx