Computer Programming
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- Can you access an instance variable from a static method? Explain why or why not.
- Can you access a static variable from an instance method? Explain why or why not.
- Consider the case where you have two classes, ClassA and ClassB, such that ClassA contains a member variable defined as ClassB myBobj. ClassB contains a constructor which takes a String parameter. ClassA provides a constructor which accepts a String parameter which is to be provided to myBobj. What needs to be done to initialize the ClassB member variable with the value from the ClassA constructor?
- Here are some class definitions with questions that follow.
public class BaseClass { // methods of BaseClass }
public SomeClass extends BaseClass
{ // methods of SomeClass }
a. SomeClass scobj = new SomeClass( );
b. BaseClass bcobj = scobj;
c. SomeClass scobj2 = bcobj;
d. bcobj.aMethodOfSomeClass( ); // does not exist in BaseClass
A. Is statement babove legal, or is casting required?
B. Statement c is trying to assign the SomeClass object referred to by bcobj to a SomeClass reference variable scobj2. What is wrong with this statement and how would you fix it.
C. In statement d, a BaseClass reference is trying to access a SomeClass class method that is not part of BaseClass. Is this legal? Explain.
- Give an example using Java syntax of how some class Y can be setup to inherit from some other class X.
- What is a significant difference between C++ and Java inheritance?
- How is the keyword super used? Give two different uses for it and include Java examples.
- Explain the difference betweenpublic, private, and protectedaccess specifiers. Give some guidelines of when each should be used.
- Explain what package access means and how it is specified.
- What can you do in Java to prevent a method from being overridden in a derived class? Give example code in your answer.
- How do you prevent a class from being extended? Give example code in your answer.
- Explain how dynamic binding works in Java.
