Java Basic Interview Questions

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    1. What can be learned from “Hello World”?
    2. How to build your own library?
    3. Whan and how a class is loaded and initialized?
    4. Static Type Checking
    5. How to get double?
    6. What is string immutability?
    7. Why string is immutable in Java?
    8. Is string passed by reference?
    9. length vs length()
    10. What exactly is null in Java?
    11. Comparator vs. Comparable
    12. The contract between hashCode() and equals()
    13. Overloading vs Overriding
    14. What is instance initializer?
    15. Fields can not be overridden?
    16. 4 types of Java inner classes
    17. Inner Interface in Java
    18. Constructors of Sub and Super classes？
    19. Public, protected, and private
    20. When to use private constructors?
    21. How exception handling works?
    22. Class hierarchy of exceptions
    23. Read file line by line
    24. Write file line by line
    25. FileOutputStream vs. FileWriter
    26. Should .close() be put in finally block or not?
    27. How to use properties file?(explain the code)

When multithreading is useful?

    1. Monitors – The Basic Idea of Java synchronization
    2. Class hierarchy of Collection and Map
    3. A TreeSet Example
    4. Deep Understanding of Arrays.sort(T[], Comparator < ? super T > c)
    5. ArrayList vs. LinkedList vs. Vector
    6. HashSet vs. TreeSet vs. LinkedHashSet
    7. HashMap vs. TreeMap vs. HashTable vs. LinkedHashMap
    8. Efficient Counter in Java
    9. Frequently Used Methods of Java HashMap
    10. What is Type Erasure?
    11. Why do we need Generic Types in Java?
    12. Set vs. Set<?>

Use Map or HashMap as declaration types?

    1. What’s the best way of converting Array to ArrayList?
    2. Java passes object by reference or by value?
    3. Reflection tutorial
    4. What is framework?
    5. Why do we need Java web frameworks like Struts 2?

What is JVM?

    1. JVM run-time data areas

How GC works?

    1. How does Java handle aliasing？
    2. What does an array look like in memory?
    3. What is memory leak?
    4. What is Servlet Container? What is Tomcat?
    5. Why do we need software testing?
    6. What is Aspect Oriented Programming?
    7. Library vs. Framework?
    8. Convert java jar file to exe
    9. Java and Computer Science Courses

How Compiler Works?
Type Checking for Object Oriented Features

    1. Generate Code for Overloaded and Overridden Methods?
    2. How CVS works?
    3. Top 8 Diagrams for Understanding Java
    4. Top 10 Methods for Java Arrays
    5. Top 10 questions of Java Strings
    6. Top 10 Questions for Java Regular Expression
    7. Top 10 Questions about Java Exceptions
    8. Top 10 questions about Java Collections
    9. Top 9 questions about Java Maps
    10. The Most Widely Used Java Libraries

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  16. JSoup
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  18. Create thread by overriding(another way, difference)
  19. join()
  20. notify() and wait() (output use other format maybe)
  21. Date Formatting(add more)
  22. Path of package and class
  23. Iteration vs. Recursion
  24. Why do we need reflection? (add more)
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