Important Android Topics To Study If You Are Going To Be Android Developer

Most important Android topics to be studied :

1. Java Basics & OOP Concepts
2. Java Collections.
3. Java Class / Objects 
4. Threading.
   - Life Cycle  & Types
5. Java Exceptions Handling
6. Synchronization
   -Types. 
7. Serialization/Di serialization
8. Interface
9. String /String Buffer/String Builder.
  - difference between these three.
  - Where to use /usage.
10. Static, Final  
  - Uses of static keyword.
11. Access Modifiers
  - public, private, protected
12. Sorting Algorithms 
  - Bubble sort
  - Quick sort.
  - selection sort.
  - Insertion sort.
  - Merge sort
13. Java Data structure.
   - Stack.
   - Queue.
   - Linked list.
14. Java Annotations.
  - @Deprecated
  - @Override
  - @SuppressWarnings
15. Java Basic I/O Operations.
  I/O Streams :
    - Byte Streams handle I/O of raw binary data.
    - Character Streams handle I/O of character data, automatically handling translation to and from the local character set.
    - Buffered Streams optimize input and output by reducing the number of calls to the native API.
    - Scanning and Formatting allows a program to read and write formatted text.
    - I/O from the Command Line describes the Standard Streams and the Console object.
    - Data Streams handle binary I/O of primitive data type and String values.
    - Object Streams handle binary I/O of objects.
  File I/O :
    -  Java - Streams, Files and I/O
16. Basic Networking concepts.
17. Nested classes.
       If a class is declared within another class or interface is called nested class.
    Types of nested classes are as given below:
    - Static Member Classes: It is defined as static member in a class or an interface.
    - Non-static Member Classes: It is defined as instance members of another classes.
    - Local Classes: It is defined in a block, like inside a method body or a local block.
    - Anonymous Classes: It can be defined as expressions and instantiated on the fly.
19. Basics of Regular Expression.
20. Garbage Collection
   In Java unused objects are deleted by a process known as garbage collection. 
The JVM automatically runs garbage collection periodically. Garbage collection:
    Identifies objects no longer in use (no references)
    Finalizes those objects (deconstructs them)
    Frees up memory used by destroyed objects
    Defragments memory 
Garbage collection introduces overhead, and can have a major affect on Java application performance.
    The goal is to avoid how often and how long GC runs.
    Programmatically, try to avoid unnecessary object creation and deletion.
    Most JVMs have tuning parameters that affect GC performance. 



Note: For each topics this question should be asked  Q. Where to use /When to use / How to use/How to create ???