Where can get the Android source code?

Such as when I use the ArrayAdapter 开发者_运维技巧class, I want to know what is be done in the class. Sometimes I want to go the source code to find answer. So, my question is where can get the source code ?

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http://source.android.com/source/index.html

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http://grepcode.com/snapshot/repository.grepcode.com/java/ext/com.google.android/android/2.3_r1/

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https://android.googlesource.com/platform/frameworks/base/+/froyo-release/core/java/android/widget/ArrayAdapter.java

is the link for ArrayAdapter used in the latest Froyo release from Googles open source repository. You can use the navigation links on that page to get to the other parts of the available source code and other releases of Android.