Q:

Building a particular module in the android source code

I am working on an android source code which I have downloaded from source.android.com. 
After a full build I went through this site http://elinux.org/Android_Build_System which explains the android build system. 
When I make changes in external/webkit code and build it with 
make -j4 libwebcore it compiles the corresponding file and updates the libwebcore.so, and it save me a lot of time. 
The same thing is applied to applications and also for building apks. 
The problem arises when I make changes in the framework and give the command as
make -j4 framework  its not compiling the corresponding files. 
Can any one help me! 

A:

The folder frameworks contains many things, you have to be more specific about telling make what to build. 
For example I made a change in:
frameworks/base/cmds/input/src/com/android/commands/input/Input.java. 
Now the corresponding Android.mk file is located in:
frameworks/base/cmds/input/Android.mk, which contains a line saying: LOCAL_MODULE := input. 
Thus the module being build from the source is called input, so I call:
$ make input

Which rebuilds that specific module. 
As a bonus info, you can use the mmm helper and you can specify the path of the module to build like this:
$ mmm frameworks/base/cmds/input

or using mm which just builds the module in you current working directory:
$ cd frameworks/base/cmds/input
$ mm

I normally use mmm as my preferred tool. 

Update
Oh, I see you might be talking specifically about the module called framework
I just tried to modify: frameworks/base/core/java/android/app/Dialog.java, and do a: make framework. 
This seems to recompile the framework just fine.  Which file exactly are you making changes in before running make framework ? 

In response to your comment
I just tried to modify frameworks/base/core/java/android/webkit/WebView.java.  mmm frameworks/base as well as make framework works perfectly fine for me. 
If it does not work for you, can you update your question with additional information about which android version you are building, which commands you are typing exactly, and the output your are seeing? 

A:

Here are fuller descriptions of mm, mmm, and other convenient functions provided by sourcing the build/envsetup.sh file:
Invoke .  build/envsetup.sh from your shell to add the following functions to your environment:
   lunch:   lunch <product_name>-<build_variant>
   tapas:   tapas [<App1> <App2> ...] [arm|x86|mips|armv5] [eng|userdebug|user]
   croot:   Changes directory to the top of the tree. 
   m:       Makes from the top of the tree. 
   mm:      Builds all of the modules in the current directory, but not their dependencies. 
   mmm:     Builds all of the modules in the supplied directories, but not their dependencies. 
            To limit the modules being built use the syntax: mmm dir/:target1,target2. 
   mma:     Builds all of the modules in the current directory, and their dependencies. 
   mmma:    Builds all of the modules in the supplied directories, and their dependencies. 
   cgrep:   Greps on all local C/C++ files. 
   jgrep:   Greps on all local Java files. 
   resgrep: Greps on all local res/*.xml files. 
   godir:   Go to the directory containing a file. 

Plese check build/envsetup.sh file's comments to see full list of functions.