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Beta |
Frozen |
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Vocabulary & Concepts 1 question
State the significance of the following acronyms : JCP, JSR, JDBC ... other suggestions are welcome
Know how Sun counts (1.0, 1.1, 1.2 = Java 2, 1.3, 1.4, 1.5 = Java 5, 1.6 = Java 6) and that there was no Java 3 or Java 4.
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15 |
0 |
96 |
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Language Syntax
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Flow Control 2 questions
Create Loops
- Write code using all kind of Java loops : for, while, do-while and for each (introduced in Java 5)
- Predict behavior of nested loops
- Use break and continue in nested loops, both unlabeled and labeled syntaxes.
Define Branching
- Write syntactically correct tests using if, switch structures
- Define correct types of arguments for both keywords
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80 |
434 |
114 |
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Operators 2 questions
Ternary Operator
- Use correct syntax and explain the ternary x ? y : z operator
- Identify correct operands and return type compatibility
Bitwise Operators
- Manipulate primitives using the bitwise manipulation operators ~, & and |
Shift Operators
- Understanding shift operators
- >> (SHIFT RIGHT operator)
- << (SHIFT LEFT operator) and
- >>> (UNSIGNED SHIFT RIGHT operator)
- Code Snippets using the >>, <<, and >>>
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64 |
280 |
135 |
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Primitive Types 1 question
Types
- For each Java primitive type explain its purpose, its default value, its value range
Literals
- For the char literals, explain the meaning of \u, \n, \t, \', \" literals
- For the integral literals, only the decimal notation is covered (neither octal nor hexadecimal)
- For the floating point literals
- explain the meaning of the e, f, d suffixes
- use the Float/Double.NaN, .NEGATIVE_INFINITY, .POSITIVE_INFINITY constants
- Use the L(l) suffix to get a long literal instead of an int
Conversion
- Explain the widening conversion chain byte -> short -> int -> long -> float -> double
- Given code, spot valid and invalid primitive types casting operations
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14 |
509 |
69 |
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Keywords 1 question
Keywords
- Recognize reserved Java keywords
- In general terms, explain the application of each keyword
static
- Write code that defines class attributes using the static keyword and manipulate them
- Define class method, explain how to call them
final
- Explain how to define constant attributes using final
- Identify places where blank final can be initialized
- Describe the meaning of final applied to methods
- Prevent classes from being subclassed by declaring them final
transient
- Explain the usefulness of the transient modifier in the Serialization process
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11 |
563 |
31 |
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Assertions 1 question
- Write code that uses Assertions
- State how to enable Assertions
- Identify the exception type raised when reaching a false assertions
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20 |
77 |
101 |
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Class
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Lifecycle 2 questions
- Understand the new operator to create an object.
- Determine the initialization sequence of fields, static fields, static block, constructor, ancestor constructors
- Explain the use of this() and super() in constructors and identify where you can call them
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83 |
190 |
102 |
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Inner class 2 questions
- Write code that define basic inner classes (anonymous or not)
- Explain the usage of the outer class "this", in the inner class
- Use final modifier for local variables in enclosing classes to get access to it
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67 |
259 |
108 |
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Class Loading 1 question
- Explain the Java SE classpath mechanism
- Understand the ClassLoader hierarchy and implications on the static scope.
- Given an object instance get its ClassLoader from its Class
- Get the system classloader using ClassLoader.getSystemClassLoader()
- Write code that uses ClassLoader to load external resources on the file system.
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18 |
0 |
61 |
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Overloading 1 question
- Explain the overloading mechanism
- Identify the method name, arguments types and order differentiates 2 method signatures
- Explain why the return type does not differentiate 2 methods
- Given code, determine method resolution behavior when using polymorphism in parameters including Java 5 Autoboxing and varargs
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16 |
248 |
27 |
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Inheritance
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Object 1 question
- Identify methods inherited from the Object class.
- Explain correct implementation of the equals() and hashCode() and the contract between them. Describe the behavior of the default implementation.
- Write correct implementation of the toString() method.
- Write code that given an instance gets an instance of the Class class.
- Explain the meaning of the clone() method.
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16 |
239 |
27 |
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Overriding 1 question
- Explain the overriding mechanism and late binding
- Identify correct overriding syntax, distinguish between the overriding and overloading mechanism.
- State what you can and cannot do with access specifiers in overriding methods
- State what you can and cannot do with thrown exceptions in overriding methods
- Establish the difference between super. and super()
- Explain data hiding
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8 |
373 |
31 |
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Abstract 2 questions
- Write code that declares abstract classes and methods
- Explain why an abstract class cannot be instantiated but has a constructor
- Identify correct modifiers combinations, ex: Can a method be declared as final abstract ?
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74 |
94 |
104 |
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Interfaces 1 question
- Write code that declares an interface and its containing methods
- Explain the particular nature of attributes declared in interfaces
- Identify the modifiers that can be applied to interface methods; given code spot which are needed and which are redundant
- Troubleshoot class that implements multiple interfaces
- declaring methods with same name but different return type
- declaring attributes having the same name
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15 |
545 |
32 |
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RTTI 1 question
- Write code that uses the instanceof operator for run-time type identification.
- Identify correct operands of the instanceof operator
- Given an instance, retrieve an instance of the Class class and state how to get the fully qualified class name of the class
- Explain the Class.isInstance() method usage
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26 |
1 |
64 |
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Exceptions 3 questions
- Create and throw a custom exception class.
- Use the throws keyword.
- Know the java standard exception hierarchy for: Throwable, Error, OutOfMemoryError, Exception, RuntimeException, NullPointerException, IOException...
- Understand execution flow for nested try/catch/finally clauses.
- Understand and use nested exceptions.
- Differentiate checked and unchecked exceptions.
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118 |
236 |
120 |
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Threads 2 questions
Create and Start a new Thread
- Write code that creates a new Thread by extending the Thread class
- Write code that creates a new Thread by implementing a Runnable object
- Write code that creates a new Thread by implementing a Callable object
- State how to start a thread (using the .start() method)
- State what happens when you explicitly call the run() method
Synchronized
- Use a synchronized block to lock object instances and prevent concurrent access
- Use the synchronized modifier on methods, define the equivalent syntax using a synchronized block
- Explain the locking mechanism.
Lifecycle and methods
- Explain what a daemon is and write code that turns a Thread into a daemon
- Write code that
- gets the current Thread using Thread.currentThread()
- tests if a thread is active using Thread.isAlive()
- makes a thread wait using Thread.sleep(long millis)
- makes a thread wait for another thread using Thread.join()
- create cooperative thread using Thread.yield()
Wait and Notify
- Explain the wait() and notify() mechanism
- Identify in which circumstances a class can call wait() on an object
- Explain scenarios where an IllegalMonitorStateException can be thrown
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20 |
664 |
80 |
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Java SE Core - Intermed
