Second Summer 2002


Lab Notes Four: The warm-ups.

Questions:

  1. Explain the difference between an object and a class.

  2. Give the Java code for an

  3. Explain the differences between an instance variable and a local (or method) variable.

  4. Explain the difference between
    new BankAccount(5000); 
    and
    BankAccount b;

  5. What are the construction parameters for a BankAccount object?

  6. What is default construction?

  7. Give Java code to construct the following objects:

    Write just objects, not object variables.

  8. Repeat the preceding exercise, but now

  9. Find the errors in the following statements:
    Rectangle r = (5, 10, 15, 20); 
    
    double x = BankAccount(10000).getBalance(); 
    
    BankAccount b;
    b.deposit(10000); 
    b = new BankAccount(10000);
    b.addCoins(new Coin(0.25, "quarters")); 
    
    Purse p = null; 
    p.addCoins(new Coin(0.25, "quarters")); 
    
    Purse p = new Purse(); 
    p.addCoins(new Coin()); 
    

  10. Describe all constructors of the BankAccount class. List all methods that can be used to change a BankAccount object. List all methods that don't change the BankAccount object.

  11. What is the value of b after the following operations?
    BankAccount b = new BankAccount(10); 
    b.deposit(5000);
    b.withdraw(b.getBalance() / 2); 

  12. If b1 and b2 store objects of class BankAccount, consider the following instructions.
    b1.deposit(b2.getBalance());
    b2.deposit(b1.getBalance());
    Are the balances of b1 and b2 now identical? Explain.

  13. What is the this reference?

These are all questions from the book.


Last updated: Jun 16, 2002 by Adrian German for A201