1. Recognize literal strings.
2. Be familiar with the 2 most common of String's 9 constructors.

• String ()
• String (String s)

3. Be aware that Strings are immutable objects.
4. Understand how Strings are initialized.

• String s1 = " ";                   //s1 is set to an empty String
• String s2 = new String();  //s2 is set to an empty String
• String s3;                           //s3 is set to null

5. Be aware that calling a String method with a String set to null will give run-time errors. (An empty string initialized to " " is not the same thing as a string initialized to null.)
6. Correctly use common String methods (See table on p. 265.)

• length()
• charAt (pos)    //Note that characters are counted starting at 0.
• substring (pos)
• substring (fromPos, toPos)
• compareTo (s2)  //returns neg int if s1 <s2, 0 if s1 = s2, pos int if s1>s2
• compareToIgnoreCase (s2)   //returns neg int if s1 <s2, 0 if s1 = s2, pos int if s1>s2 ignoring case
• equals(s2)   //returns a boolean true or false
• equalsIgnoreCase(s2)  //returns a boolean true or false ignoring case
• indexOf (ch)   //four types
• lastIndexOf (ch)   //four types
• trim()   //removes white space characters from beginning and end of string
• replace (oldChar, newChar)
• toUpperCase()
• toLowerCase()

7. Correctly use the various ways of doing concatenation (adding Strings). (p. 266)

• yourString += str;
• yourString = yourString1 + str;
• yourString.concat (str);

8. Correctly use relational operators with Strings. p. 268)
9. CANNOT use == , != , < , >, <= , >=
10. CAN use equals(s2), equalsIgnoreCase(s2), compareTo(s2) methods, compareToIgnoreCase (s2)
11. Correctly convert numbers into Strings and Strings into numbers.

examples

Integer.parseInt(yourString)

String.valueOf(yourNumber)

12. Explain the term wrapper class.
13. Correctly use the Character wrapper class methods. (p.275)
14. Correctly use the StringBuffer class (p. 278).

Homefun: Exercises 1-6;

Programming assignments: Lab 10.8

• Write a program that inputs 2 strings using command line input.
• Output the length of both strings, the 3rd character in both strings.
• Test the strings to see if they are the same and output whether they are. Concatenate the two strings and output the result.
• Output any capital letters in the concatenated string along with their position.

Test: Chap 10 Objectives 1-13

Chapter 11: Class Hierarchies and Interfaces

1. Name 2 reasons why duplicate code is a bad idea. (wasteful, hard to maintain)
2. Explain the purpose of having a hierarchy of classes and how it helps facilitate functional decomposition ( breaking down an overwhelmingly complex task into smaller doable tasks).
3. Define polymorphism and explain why it is useful (page 293).
4. Create and use abstract methods (methods that are declared but not defined).

   Example declaration:

   public abstract int tax();  // Note that there is no code, not even brackets.

5. Create abstract classes (classes with one or more abstract methods).

Example declaration:

public abstract class People {

     . . .

}

6. Correctly declare an interface.

Example declaration:

public interface Career {

     . . .

}

7. Define the term concrete class.

Has no abstract methods.

8. Be aware that all classes automatically extend the class Object.
9. State the difference between an interface, abstract class, and concrete class.
10. Be aware that Java does not allow the creation of objects (instances) of an abstract class or an interface.
11. Describe the reasons for using an interface.

• A class can only extend one class but can implement multiple interfaces.
• Interfaces make code readable a uniform by standardizing terms (fields) and procedures (methods).

12. Be aware that if a class implements an interface (and it can implement as many as it wants), it must supply all the methods specified in the interface.
13. Invoke a superclass's constructors (p.298).

• a superclass's constructors must be used to initialize private fields
• a superclass's constructors can be called inside the subclasses constructor using super (<appropriate arguments>);
• if the superclass's constructor is not called the no-arguments-constructor of the superclass is run by default
• if there is not a no-arguments-constructor, an error message results

14. Write programs that extend a given class using inheritance.
15. Write programs that implement interfaces.
16. Explain how polymorphism applies to interfaces.

Homefun: Exercises 1-5

Programming assignments: 6a

Test: Chap 11 Objectives 1-15

Chap. 12 Arrays and ArrayLists

1. Correctly declare and initialize arrays.

• int scores [ ] = new int[5];
• int scores [ ] =  { 93, 67, 99, 87, 91};

2. State the default values when initializing arrays

• numbers = 0
• boolean = false
• objects = null

3. Know that once declared and initialized, the size of an array cannot be changed.
4. Know that the elements of arrays are numbered starting with 0. These elements can be randomly accessed using the indices or subscripts.
5. Correctly use the array length field.
6. Be aware that arrays are always passed to methods by reference.
7. Correctly declare and initialize 2D arrays.

final int ROWS = 2;

final int COLS = 3;

double name2DArray [ ] [ ] = new double [ROWS][COLS];

    or

double name2DArray [ ] [ ] =

{

        {0.0, 2.7, 5.6},

        {4.3, 1.4, 7.2}

};

8. Be aware that the first dimension in a two dimension array is considered the number of rows while the second dimension is the number of columns.
9. Correctly use the length field to  find the number of rows and columns.

• twoDArray.length gives the number of rows
• twoDArray[0].length gives the number of columns

10. Be aware that arrays with more than 2 dimensions can be declared.
11. Correctly use parallel arrays.
12. State the advantage of using ArrayList. Can expand and contract as needed
13. Be familiar with ArrayList's constructors and methods (see page 331).
14. Be aware of the pitfalls of using ArrayLists.
15. Describe how classes and arrays are key elements used to form data structures.
16. Describe why abstraction is an important theme in data structures.
17. Be as one with Chapter 2 of GridWorld.

 

Homefun: Exercises 1-5;

Programming assignments: Lab 12.9, 12.11

 

12.1 Simple Data Base Program

Create a program with a class called Employees. In the main method create 3 parallel ArrayLists: 2 holding 6 first names and 6 last names plus a third ArrayList with the corresponding Salary for each employee. Use an output method concatenate the first and last names, and output the data in two columns as shown in the example:

 

Name                 Salary $1000/yr

Bob Arnold            90

Herb Bobo            12

Jane Cool             27

Alfred Nameless   49

Juan  Smith          200

Betty Taylor         142

Next, output the total of all salaries. Use a random number generator to fire two employees. Remove them from the Array List then add a new employee called Bob Newguy with a salary of $200,000. Again, output a table with the names of the current employees and their salaries. Also output the total of all salaries.

12.2 2-D Array Output

Create a program with a class called Alphabet with 3 local (inside main method) of 2-dimentional arrays: each will contain a large-sized letter respectively A, B, and C. Use a separate method to output the letters alphabetically in a column with A at the top.

Note: You need to write the letters on graph paper or in an Excel spread sheet in order to understand how many spaces are needed. To understand how the arrays should be initialized look at chapter 10 objective 7 above. You do not need to reproduce the grid lines in your program's output.

      

	0	1	2	3	4	5	6	7	8	9	10
0						A
1					A		A
2				A				A
3			A	A	A	A	A	A	A
4		A								A
5	A										A

     

 

GridWorld: Read Chapter 2, Exercises 1-4

Test: Chap 12 Objectives 1-16