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Win a copy of Helidon Revealed: A Practical Guide to Oracle’s Microservices Framework this week in the Java in General forum!
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1. Section Title: Declarations and Access Control
1.1 Write code that declares, constructs and initializes arrays of any base type using any of the permitted
forms both for declaration and for initialization.
1.2 Declare classes, nested classes, methods, instance variables, static variables and automatic (method
local) variables making appropriate use of all permitted modifiers (such as public, final, static, abstract,
etc.). State the significance of each of these modifiers both singly and in combination and state the effect
of package relationships on declared items qualified by these modifiers.
1.3 For a given class, determine if a default constructor will be created and if so state the prototype of that
constructor.
1.4 Identify legal return types for any method given the declarations of all related methods in this or parent
classes.
2. Section Title: Flow Control, Assertions, and Exception Handling
2.1 Write code using if and switch statements and identify legal argument types for these statements
2.2 Write code using all forms of loops including labeled and unlabeled, use of break and continue, and state
the values taken by loop counter variables during and after loop execution.
2.3 Write code that makes proper use of exceptions and exception handling clauses (try, catch, finally) and
declares methods and overriding methods that throw exceptions.
2.4 Recognize the effect of an exception arising at a specified point in a code fragment. Note: The
exception may be a runtime exception, a checked exception, or an error (the code may include try, catch,
or finally clauses in any legitimate combination).
2.5 Write code that makes proper use of assertions, and distinguish appropriate from inappropriate uses of
assertions.
2.6 Identify correct statements about the assertion mechanism.
3. Section Title: Garbage Collection
3.1 State the behavior that is guaranteed by the garbage collection system.
3.2 Write code that explicitly makes objects eligible for garbage collection.
3.3 Recognize the point in a piece of source code at which an object becomes eligible for garbage collection.
4. Section Title: Language Fundamentals
4.1 Identify correctly constructed package declarations, import statements, class declarations (of all forms
including inner classes) interface declarations, method declarations (including the main method that is
used to start execution of a class), variable declarations, and identifiers.
4.2 Identify classes that correctly implement an interface where that interface is either java.lang.Runnable or
a fully specified interface in the question.
4.3 State the correspondence between index values in the argument array passed to a main method and
command line arguments.
4.4 Identify all Java programming language keywords. Note: There will not be any questions regarding
esoteric distinctions between keywords and manifest constants.
4.5 State the effect of using a variable or array element of any kind when no explicit assignment has been
made to it.
4.6 State the range of all primitive formats, data types and declare literal values for String and all primitive
types using all permitted formats bases and representations.
5. Section Title: Operators and Assignments
5.1 Determine the result of applying any operator (including assignment operators and instance of) to
operands of any type class scope or accessibility or any combination of these.
5.2 Determine the result of applying the boolean equals (Object) method to objects of any combination of
the classes java.lang.String, java.lang.Boolean and java.lang.Object.
5.3 In an expression involving the operators &, |, &&, || and variables of known values state which operands
are evaluated and the value of the expression.
5.4 Determine the effect upon objects and primitive values of passing variables into methods and performing
assignments or other modifying operations in that method.
6. Section Title: Overloading, Overriding, Runtime Type and Object Orientation
6.1 State the benefits of encapsulation in object oriented design and write code that implements tightly
encapsulated classes and the relationships "is a" and "has a".
6.2 Write code to invoke overridden or overloaded methods and parental or overloaded constructors; and
describe the effect of invoking these methods.
6.3 Write code to construct instances of any concrete class including normal top level classes and nested
classes.
7. Section Title: Threads
7.1 Write code to define, instantiate and start new threads using both java.lang.Thread and
java.lang.Runnable.
7.2 Recognize conditions that might prevent a thread from executing.
7.3 Write code using synchronized wait, notify and notifyAll to protect against concurrent access problems
and to communicate between threads.
7.4 Define the interaction among threads and object locks when executing synchronized wait, notify or
notifyAll.
8. Section Title: Fundamental Classes in the java.lang package
8.1 Write code using the following methods of the java.lang.Math class: abs, ceil, floor, max, min, random,
round, sin, cos, tan, sqrt.
8.2 Describe the significance of the immutability of String objects.
8.3 Describe the significance of wrapper classes, including making making appropriate selections in the
wrapper classes to suit specified behavior requirements, stating the result of executing a fragment of code
that includes an instance of one of the wrapper classes, and writing code using the following methods of
the wrapper classes (e.g., Integer, Double, etc.):
� doubleValue
� floatValue
� intValue
� longValue
� parseXxx
� getXxx
� toString
� toHexString
9. Section Title: The Collections Framework
9.1 Make appropriate selection of collection classes/interfaces to suit specified behavior requirements.
9.2 Distinguish between correct and incorrect implementations of hashcode methods.
I understand it already.
public class Test026
{
static Test026 t = new Test026();
String str; //this is initialised to null
public static void main(String args[]) {
Test026 t = new Test026();
t.method("0");
}
void method(String str) {
str = str;
System.out.println(str);
System.out.println(t.str); //this called the instance variable str which is null
System.out.println(this.str); //this also call the instance variable str
}
}
