1. CSE 1030: Implementing Non-Static Features
Mark Shtern

2. Summary Utility Class Contracts Javadoc /** */, tags
@param Parameter_Name Parameter_Description
@return Description_Of_Value_Returned
@throws Exception_Type Explanation
@deprecated
@see Package_Name.Class_Name
@author Author
@version Version_Information

3. Ex03
Write a static method majority() that takes three boolean arguments and returns true if at least two of the arguments have the value true, and false otherwise. Do not use an if statement.

4. Ex04 Write a utility class with two methods
“testWord”: takes a String as an argument and returns false if it has received this argument before, otherwise returns true
“getDifferentWordCounter”: returns the number of different words that were tested
Write application which calculates how many different words in an input
Write application which calculates how many different words in a text file

5. Ex05
Develop ErrUtils utility which helps to print error messages. The utility will have the following interface
ErrUtils{
public static void printErr(String error);
public static void setBeepMode(boolean);
public static boolean getBeepMode();
public static final String DISK_FAILURE = “Disk Failure”; }

6. Summary Boolean expression Utility state Attributes Set &&, ||
private static Set<String> set = new TreeSet<String>()
Set
add, contains, size, remove, clear
HashSet, TreeSet

7. Class Attributes associated with instance
Class needs to be instantiated
Every class has a constructor

8. Class Attributes Methods Constructors public Counter(long a) Example
private long counter;
Methods
public double add (long a)
Constructors
public Counter(long a)

9. The this Parameter
this must be used if a parameter or other local variable with the same name is used in the method
Otherwise, all instances of the variable name will be interpreted as local
int someVariable = this.someVariable
local
instance

10. The methods equals, hashCode and toString
Java expects certain methods, such as equals, hashCode and toString, to be in all, or almost all, classes
The purpose of equals, a boolean valued method, is to compare two objects of the class to see if they satisfy the notion of "being equal"
Note: You cannot use == to compare objects
public boolean equals(ClassName objectName)
The purpose of the toString method is to return a String value that represents the data in the object
public String toString()
The purpose of the hashCode method is to return an integer that can serve a hash code for the object – it should be the same for objects that are equals
public int hashCode()

11. Tip
It is generally better to override toString, equals and hashCode methods with version that are appropriate to the class being define

12. Memory
public static void main(String[] args) { int a = 5; Point p = new Point(1.5,1.5); move(5, p); } static int move (int a,Point p){ Point p1 = p; double x = p.getX() + a; double y = p.getY() + a; p1.setLocation(x,y);
This !!!!!!!!!!!!!!!!!!!!
Note: this parameter

13. compareTo
x.compareTo(y) returns 0 if and only if y.compareTo(x) returns 0
x.compareTo(y) < 0 if and only if y.compareTo(x)>0
If x.compareTo(y) <0 & y.compareTo(z)<0 than x.compareTo(z) < 0
If x.compareTo(y) = 0 & y.compareTo(z) = 0 than x.compareTo(z) = 0

14. Ex10 Design and implement a Rectangle class
Attributes
Width
Height
Methods
getArea
Assessors, Mutators
Write application that sorts Rectangles by area