java scratchpad

finalMethodsReview.java

2006-12-14T15:41:00.000-08:00

public static int randomUpTo(int n) // generate random num up to n
{
 Random generator = new Random();
 return generator.nextInt(n);
}
public static int randomBetween(int first, int second) // inclusive
{
 Random generator = new Random();
 return generator.nextInt(second - first + 1) + first;
}
public static void printLettersOnSeparateLines(String s)
{
 for(int i = ; i < s.length(); i++)
  System.out.println(s.charAt(i));
} 
public static boolean longerThanSecond(String first, String second)
{
 return first.length() > second.length();
public static boolean comesBeforeSecond(String first, String second)
{
 return first.compareTo(second) < 0;
}
public static int countVowels(String s)
{ 
 char ch;
 int count = 0;
 for(int i = ; i < s.length(); i++)
  {
   ch = s.charAt(i);
   if(ch == 'a' || ch == 'e' || ch == 'i' || ch == '0' || ch == 'u')
    count++; 
  }
 return count;
}
public static String replaceLetterWithAsterisk(String s, char letter)
{
 for(int i = 0; i < s.length(); i++)
  if(s.charAt(i) == letter) s.charAt(i) = '*';
 return s;
}
public static boolean isAdverb(String s) // check if s ends in "ly"
{
 String ending = new String();
 ending = s.substring(s.length() - 2);
 return ending.equals("ly");
}
public static void print(int[] list)
{
 for(int i = 0; i < list.length; i++)
  System.out.println(list[i]);
}
public static void printBackwards(int[] list)
{
 for(int i = list.length - 1; i >= 0; i--)
  System.out.println(list[i]);
}  
public static int sum(int[] list)
{
 int sum = 0;
 for(int i = 0; i < list.length; i++)
  sum += list[i];
 return sum;
}
public static double average(double list[])
{
 double sum = 0;
 for(int i = 0; i < list.length; i++)
  sum += list[i];
 return sum / list.length;
}
public static int countEvens(int[] list)
{
 int count = 0;
 for(int i = 0; i < list.length; i++)
  if(list[i] % 2 == 0) count++;
 return count;
}
public static void reverse(int[] list)
{
 int[] newList = new int[list.length];
 int k = 0;
 for(int i = list.length - 1; i >= 0; i--)
  newList[k++] = list[i];
 list = newList;
} 
public static void swapPairs(int [] list) // assume even sized list
{
 int temp;
 for(int i = 0; i <= list.length - 2; i += 2)
  {
   temp = list[i];
   list[i] = list[i+1];
   list[i+1] = temp;
  }
}
public static boolean allValuesUnique(int[] list)
{
 for(int i = 0; i < list.length; i++)
  for(int j = 0; j < list.length; j++)
   if(list[i] == list[j] && i != j) return false;
 return true;
}
public static void printTable(int[][] table)
{
 for(int row = 0; row < table.length; row++)
  for(int col = 0; col < table[row].length; row++)
   System.out.println(table[row][col]);
}
public static void printRow(int[][] table, int row)
{
 for(int col = 0; col < table.length; col++)
   System.out.println(table[row][col]);
}  
public static void printCol(int[][] table, int col)
{ 
 for(int row = 0; row < table[row].length; row++)
   System.out.println(table[row][col]);
}  


public static int search(int[] list, int n) // returns the index of n else returns -1
{
 for(int i = 0; i < list.length; i++)
  if(list[i] == n) return i;
 return -1;
}
public static boolean isInOrder(int[] list)
{
 for(int i = 0; i < list.length - 1; i++)
  if(list[i] > list[i+1])
   return false;
 return true;
}
public static void printArrayList(ArrayList list) // assume list contains String objects
{
 for(int i = 0; i < list.size(); i++)
  System.out.println(list.get(i));
}
public static int myIndexOf(ArrayList list, String s)// returns the indexOf s
{
 return list.indexOf(s);
}
public static void setAll(ArrayList list, String s) // sets all of the elements in list to s
{
 for(int i = 0; i < list.size(); i++)
  list.set(i,s); 
}
public static void removeFirstAndLast(ArrayList list) // removes first and last elements of list
{
 list.remove(0);
 list.remove(list.size()-1);
}

ForEachExample.java

2006-11-26T14:26:00.000-08:00

public class ForEachExample { public static void main(String[] args) { int[] list = {1,2,3,4,5}; for(int num: list) System.out.println(num); } }

ArrayListLoops.java

2006-11-26T14:25:00.000-08:00

import java.util.*; public class ArrayListLoops { public static void main(String[] args) { ArrayList list = new ArrayList(); list.add("Washington"); list.add("Adams"); list.add("Jefferson"); list.add("Madison"); System.out.println("version 1"); for (int i = 0; i < list.size(); i++) System.out.println(list.get(i)); System.out.println("version 2"); ListIterator it = list.listIterator(); while (it.hasNext()) { System.out.println(it.next()); } System.out.println("version 3"); for(Object president: list) System.out.println((String)president); } }

DogTest.java

2006-11-02T08:15:00.000-08:00

public class DogTest{ public static void main(String[] args) { Dog d1 = new Dog("Buddy"); d1.setBreed("mutt"); d1.bark(); System.out.println(d1); System.out.println(d1.getName()); } } class Dog { private String name, breed; public Dog() { } public Dog(String name) { this.name = name; } public void setName(String name) { this.name = name; } public String getName() { return name; } public void setBreed(String breed) { this.breed = breed; } public String getBreed() { return breed; } public String toString() { return name; } public void bark() { System.out.println("bow wow"); } }

MethodsReview

2006-11-02T08:08:00.000-08:00

public static boolean isEven(int n) { return n % 2 == 0; } public static boolean isOdd(int n) { return n % 2 == 1; } public static boolean isPositive(int n) { return n > 0; } public static boolean isPrime(int n) { boolean isPrime = true; for(int i = 2; i < n; i++) if (n % i == 0) isPrime = false; return isPrime; } public static boolean isATriangle(int numSides) { return numSides == 3; } public static boolean isEquilateral(int side1, int side2, int side3) { return side1 == side2 && side2 == side3; } public static boolean isRightTriangle(int angle1, int angle2, int angle3) { return angle1 == 90 || angle2 == 90 || angle3 == 90; } public static boolean isVowel(char c) // precondition: c is lowercase { return c == 'a' || c == 'e' || c == 'i' || c == 'o' || c == 'u'; } public static int countVowels(String s) // use isVowel(char c) { int count = 0; for(int i = 0; i < s.length() i++) if(isVowel(c)) count++; return count; } public static boolean isAlphabetic(char c) { return ( c >= 'a' & c <= 'z') || ( c >= 'A' & c <= 'Z') ; public static boolean isConsonant(char c) // Use above methods { return isAlphabetic(c) && ! isVowel(c); } public static double areaSquare(double side1, double side2) { return side1 * side2; } public static double areaCircle(double radius) { return Math.PI * Math.pow(radius,2); } public static boolean isInRange(int num, int bottom, int top) { return n >= bottom && num <= top; } public static int sumRange(int bottom, int top) // inclusive { int sum = 0; for (int i = bottom; i <= top; i++) sum += i; return sum; } public static int averageRange(int bottom, int top) // inclusive { int count = top - bottom + 1; return sumRange(top, bottom) / count; } public static int min(int num1, int num2) { if(num1 < num2) return num1; else return num2; } public static int max(int num1, int num2) { if(num1 > num2) return num1; else return num2; }

CarTest

2006-10-24T11:03:00.000-07:00

public class CarTest { public static void main(String[] args) { Car c1 = new Car("Toyota"); c1.drive(50); System.out.println(c1 + " mileage = " + c1.getMileage()); c1.drive(50); System.out.println(c1 + " mileage = " + c1.getMileage()); System.out.println("total cars = " + Car.getCount()); Car c2 = new Car("Honda"); c2.drive(10); System.out.println(c2 + " mileage = " + c2.getMileage()); c2.drive(15); System.out.println(c2 + " mileage = " + c2.getMileage()); System.out.println("total cars = " + Car.getCount()); } } class Car { private String make; private int mileage; private static int count = 0; public Car(String make) { this.make = make; count++; } public String getMake() { return make; } public int getMileage() { return mileage; } public static int getCount() { return count; } public String toString() { return make; } public void drive(int miles) { mileage += miles; } }

Program3_5

2006-09-21T08:14:00.000-07:00

import java.util.*; public class Program3_5 { public static void main(String[] args) { Scanner scan = new Scanner(System.in); String s; System.out.print("Enter a string: "); s = scan.next(); for(int i = 0; i < s.length(); i++) System.out.println(s.charAt(i)); } }

ForLoopExample

2006-09-21T08:03:00.002-07:00

public class ForLoopExample { public static void main(String[] args) { for(int num = 1; num <= 10; num++) System.out.println(num); } }

WhileExample2

2006-09-21T08:03:00.001-07:00

public class WhileExample2 { public static void main(String[] args) { int num = 1; while(num <= 10) { System.out.println(num); num++; } } }

WhileExample

2006-09-21T08:03:00.000-07:00

import java.util.*; public class WhileExample { public static void main(String[] args) { String response = "y"; Scanner scan = new Scanner(System.in); while (response.equalsIgnoreCase("y")) { //code goes here System.out.print("Again? (y/n): "); response = scan.next(); } } }

AreaRectangle2

2006-08-31T08:45:00.000-07:00

import java.util.*; public class AreaRectangle2 { public static void main(String[] args) { Scanner scan = new Scanner(System.in); int area, length, width; System.out.print("Enter length: "); length = scan.nextInt(); System.out.print("Enter width: "); width = scan.nextInt(); area = length * width; System.out.println("The area of the rectangle is " + area); } }

Demo2.java

2006-02-18T15:52:00.002-08:00

public class Demo2 { public static void main(String[] args) { for (int i = 0; i < args.length; i++) System.out.println("You entered " + args[i]); } }

WrapperDemo.java

2006-02-18T15:52:00.001-08:00

import java.util.*; public class WrapperDemo { public static void main(String[] args) { ArrayList numList = new ArrayList(); numList.add(2006); int num; // num = numList.get(0); this won't work num = (Integer)numList.get(0); System.out.println(num); } }

BookTest.java

2006-02-18T15:52:00.000-08:00

import java.util.*; public class BookTest { public static void main(String[] args) { ArrayList aList = new ArrayList(); Book b1 = new Book("Catcher In The Rye"); Book b2 = new Book("Crime and Punishment"); aList.add(b1); aList.add(b2); for (int i = 0; i < aList.size(); i++) { // System.out.println(aList.get(i).getName()); THIS WON'T WORK Book b = (Book) aList.get(i); // ArrayList object must be typecast as Book System.out.println(b.getName()); } System.out.println("There are " + Book.getCount() + " books."); } }

Total.java

2006-02-18T15:51:00.001-08:00

public class Total { public static void main(String[] args) { int total = 0; for(int i = 0; i < args.length; i++) total += Integer.parseInt(args[i]); System.out.println("total equals " + total); } }

Book.java

2006-02-18T15:51:00.000-08:00

public class Book { private String name; static int count = 0; public Book() { count++; } public Book(String name) { this.name = name; count++; } public void setName(String name) { this.name = name; } public String getName() { return name; } public String toString() { return name; } public static int getCount() { return count; } }

Demo.java

2006-02-18T15:49:00.003-08:00

public class Demo { public static void main(String[] args) { System.out.println("You entered " + args[0]); } }

ArraysAsParameters.java

2006-02-18T15:49:00.002-08:00

public class ArraysAsParameters { public static void main(String[ ] args) { String president = "Bill Clinton"; String[] list = {"John","Paul","George","Pete"}; change(president); change(list); System.out.println(president); for(int k = 0; k < list.length; k++) System.out.println(list[k]); } public static void change(String[] list) { list[3] = "Ringo"; } public static void change(String president) { president = "George Bush"; } }

Multiply.java

2006-02-18T15:49:00.001-08:00

public class Multiply { public static void main(String[] args) { int num1 = Integer.parseInt(args[0]); int num2 = Integer.parseInt(args[1]); int product = num1 * num2; System.out.println("Product equals " + product); } }

CreateArrayLists.java

2006-02-18T15:49:00.000-08:00

import java.util.*; public class CreateArrayLists { public static void main(String[ ] args) { ArrayList planets = new ArrayList(); planets.add("Mercury"); planets.add("Venus"); planets.add("Mars"); planets.add("Earth"); for(int k = 0; k < planets.size(); k++) System.out.println(planets.get(k)); System.out.println(); planets.set(2,"Earth"); planets.set(3,"Mars"); Iterator it = planets.iterator(); // ArrayLists implement the List interface while (it.hasNext()) { System.out.println(it.next()); } String s = (String)planets.get(2); System.out.println(s); } }

CreateArrays.java

2006-02-18T15:48:00.000-08:00

public class CreateArrays { public static void main(String[] args) { int[] intArray = new int[5]; // create array using new operator int[] intArray2 = {1492, 1776, 1860, 1917, 1945}; // initalizer list String[] stringArray = new String[5]; String[] stringArray2 = {"mon","tue","wed","thu","fri"}; printIntArray(intArray); printIntArray(intArray2); printStringArray(stringArray); printStringArray(stringArray2); } public static void printIntArray(int[] list) { for(int i = 0; i < list.length; i++) System.out.println(list[i]); System.out.println(); } public static void printStringArray(String[] list) { for(int i = 0; i < list.length; i++) System.out.println(list[i]); System.out.println(); } }

Server.java

2006-02-16T16:40:00.002-08:00

import cs1.*; import java.text.*; public class Server { private String name; public Server(String name) { this.name = name; } public String getName() { return name; } public String toString() { return name; } public void greet() { System.out.println("Hello, my name is " + name); System.out.println("I will be your server today."); } public void serve(Customer c, Menu m) { System.out.println(); System.out.println("Menu"); m.display(); for (;;) { System.out.print("Please select from the menu (0 to quit): "); int item = Keyboard.readInt(); if (item <= 0) { break; } if (item > m.numberOfMenuItems()) { System.out.println("Sorry, that's not a valid item number."); } else { c.order(item); } } System.out.println("\n" + "Order summary for customer #" + c.getNumber() + ": "); c.displayOrder(); double subtotal = c.getSubtotal(); NumberFormat money = NumberFormat.getCurrencyInstance(); System.out.println("Subtotal = \t" + money.format(subtotal)); System.out.println("Tax = \t\t" + money.format(c.getTax(subtotal))); System.out.println("Total = \t" + money.format(c.getTotal(subtotal))); System.out.println("==================================="); } }

Menu.java

2006-02-16T16:40:00.001-08:00

import java.text.*; import java.util.*; public class Menu { ArrayList item = new ArrayList(); ArrayList price = new ArrayList(); public Menu() { } public void display() { NumberFormat money = NumberFormat.getCurrencyInstance(); for (int i = 0; i < item.size(); i++) { System.out.println((i + 1) + "\t" + item.get(i) + "\t" + money.format(price.get(i))); } System.out.println(); } public void addItem(String s, double d) { item.add(s); price.add(new Double(d)); } public String getItem(int i) { return (String) item.get(i); } public double getPrice(int i) { return ((Double) price.get(i)).doubleValue(); } public int numberOfMenuItems() { return item.size(); } }

Restaurant.java

2006-02-16T16:40:00.000-08:00

import java.util.*; import cs1.*; public class Restaurant { public static void main(String[] args) { Locale.setDefault(Locale.US); // So monetary output uses $ Orders orders = new Orders(); Menu m1 = new Menu(); boolean nextCustomer = false; String response; m1.addItem("Hamburger", 2.50); m1.addItem("French fries", 1.50); m1.addItem("Soft drink", 1.00); Server s1 = new Server("Kevin"); do{ Customer c = new Customer(m1); orders.addCustomer(c); s1.greet(); s1.serve(c, m1); System.out.print("Next customer? (y/n): "); response = Keyboard.readString(); nextCustomer = response.equals("y"); } while (nextCustomer); orders.displayOrders(); orders.displayTotal(); } }

Customer.java

2006-02-16T16:39:00.002-08:00

import java.text.*; import java.util.*; public class Customer { final static double TAXRATE = 0.0825; private static int nextCustomerNumber; private int customerNumber; private ArrayList orderList = new ArrayList(); private Menu menu; // the menu the customer is ordering from private double total; public Customer(Menu m) // customer will order from menu m { menu = m; customerNumber = nextCustomerNumber + 1; nextCustomerNumber++; } public int getNumber() { return customerNumber; } public String toString() { return Integer.toString(customerNumber); } public void order(int item) { // If the menu has N items, someone orders an item using a number // from 1 through N. Internally, our program will represent these // using the numbers 0 through N-1. orderList.add(new Integer(item - 1)); } public void displayOrder() { NumberFormat money = NumberFormat.getCurrencyInstance(); for (int i = 0; i < orderList.size(); i++) { int itemNumber = ((Integer) orderList.get(i)).intValue(); System.out.println(menu.getItem(itemNumber) + "\t" + money.format(menu.getPrice(itemNumber))); } System.out.println(); } public double getSubtotal() { double subtotal = 0.0; for (int i = 0; i < orderList.size(); i++) { int itemNumber = ((Integer) orderList.get(i)).intValue(); subtotal += menu.getPrice(itemNumber); } return subtotal; } public double getTax(double subtotal) { return subtotal * TAXRATE; } public double getTotal(double subtotal) { total = subtotal + getTax(subtotal); return subtotal + getTax(subtotal); } public double returnTotal() { return total; } }

Orders.java

2006-02-16T16:39:00.001-08:00

import java.text.*; import java.util.*; public class Orders { private ArrayList customerList = new ArrayList(); private Customer c; private double totalSales = 0.0; public Orders() { } public void addCustomer(Customer c){ customerList.add(c); } public void displayOrders(){ System.out.println("All Orders"); System.out.println("----------"); for(int i = 0; i < customerList.size(); i++){ c = (Customer)customerList.get(i); c.displayOrder(); } } private double calcTotalSales(){ for(int i = 0; i < customerList.size(); i++){ c = (Customer)customerList.get(i); totalSales += c.returnTotal(); } return totalSales; } public void displayTotal() { NumberFormat money = NumberFormat.getCurrencyInstance(); System.out.println("Total Sales (including tax)"); System.out.println("----------"); System.out.println(money.format(calcTotalSales())); } }

Fahrenheit.java

2006-02-02T15:38:00.000-08:00

public class Fahrenheit { public static void main (String[] args) { FahrenheitGUI converter = new FahrenheitGUI(); converter.display(); } }

FahrenheitGUI.java

2006-02-02T15:33:00.000-08:00

//******************************************************************** // FahrenheitGUI.java Author: Lewis/Loftus/Cocking // // Demonstrates the use of JFrame and JTextArea GUI components. //******************************************************************** import java.awt.*; import java.awt.event.*; import javax.swing.*; public class FahrenheitGUI { private int WIDTH = 300; private int HEIGHT = 75; private JFrame frame; private JPanel panel; private JLabel inputLabel, outputLabel, resultLabel; private JTextField fahrenheit; //----------------------------------------------------------------- // Sets up the GUI. //----------------------------------------------------------------- public FahrenheitGUI() { frame = new JFrame ("Temperature Conversion"); frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE); inputLabel = new JLabel ("Enter Fahrenheit temperature:"); outputLabel = new JLabel ("Temperature in Celsius: "); resultLabel = new JLabel ("---"); fahrenheit = new JTextField (5); fahrenheit.addActionListener (new TempListener()); panel = new JPanel(); panel.setPreferredSize (new Dimension(WIDTH, HEIGHT)); panel.setBackground (Color.yellow); panel.add (inputLabel); panel.add (fahrenheit); panel.add (outputLabel); panel.add (resultLabel); frame.getContentPane().add (panel); } //----------------------------------------------------------------- // Displays the primary application frame. //----------------------------------------------------------------- public void display() { frame.pack(); frame.setVisible(true); } //***************************************************************** // Represents an action listener for the temperature input field. //***************************************************************** private class TempListener implements ActionListener { //-------------------------------------------------------------- // Performs the conversion when the enter key is pressed in // the text field. //-------------------------------------------------------------- public void actionPerformed (ActionEvent event) { int fahrenheitTemp, celsiusTemp; String text = fahrenheit.getText(); fahrenheitTemp = Integer.parseInt (text); celsiusTemp = (fahrenheitTemp-32) * 5/9; resultLabel.setText (Integer.toString (celsiusTemp)); } } }

PoundstoKilograms.java

2006-02-01T22:06:00.000-08:00

public class PoundstoKilograms { public static void main(String[] args) { String title = new String("Weight conversion"); String label1 = new String("Pounds"); String label2 = new String("Kilograms"); PoundstoKilogramsGUI converter = new PoundstoKilogramsGUI(title, label1, label2); converter.display(); } }

PoundstoKilogramsGUI.java

2006-01-31T16:29:00.000-08:00

import java.awt.*; import java.awt.event.*; import javax.swing.*; public class PoundstoKilogramsGUI { private int WIDTH = 300; private int HEIGHT = 75; private JFrame frame; private JPanel panel; private JLabel inputLabel, outputLabel, resultLabel; private JTextField pounds; public PoundstoKilogramsGUI(String title, String label1, String label2) { frame = new JFrame (title); frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE); inputLabel = new JLabel (label1); outputLabel = new JLabel (label2); resultLabel = new JLabel ("---"); pounds = new JTextField (5); pounds.addActionListener (new TempListener()); panel = new JPanel(); panel.setPreferredSize (new Dimension(WIDTH, HEIGHT)); panel.setBackground (Color.yellow); panel.add (inputLabel); panel.add (pounds); panel.add (outputLabel); panel.add (resultLabel); frame.getContentPane().add (panel); } public void display() { frame.pack(); frame.setVisible(true); // book has old version } private class TempListener implements ActionListener { public void actionPerformed (ActionEvent event) { Double poundsTemp, kilogramsTemp; String text = pounds.getText(); poundsTemp = Double.parseDouble(text); kilogramsTemp = poundsTemp / 2.2 ; resultLabel.setText (Double.toString (kilogramsTemp)); } } }

MyClassTest.java

2006-01-31T16:07:00.000-08:00

import java.util.*; public class MyClassTest { public static void main(String[] args) { MyClass object1 = new MyClass("sam"); MyClass object2 = new MyClass("bruce"); MyClass object3 = new MyClass("fred"); MyClass[] list = {object1, object2, object3}; for(int i = 0; i < list.length; i++) System.out.println(list[i]); ArrayList alist = new ArrayList(); alist.add(object1); alist.add(object2); alist.add(object3); Iterator it = alist.iterator(); while(it.hasNext()) { System.out.println(it.next()); } System.out.println("There are " + MyClass.getCount() + " objects."); } }

MyClass.java

2006-01-31T15:48:00.000-08:00

public class MyClass { private String name; private static int count; public MyClass() { count++; } public MyClass(String name) { this.name = name; count++; } public void setName(String name) { this.name = name; } public String getName() { return name; } public String toString() { return name; } public static int getCount() { return count; } }

Dog.java

2006-01-31T15:40:00.000-08:00

public class Dog implements Animal { private String name; public Dog() { } public Dog(String name) { this.name = name; } public void setName(String name) { this.name = name; } public String getName() { return name; } public String toString() { return name; } public void speak() { System.out.println("bow wow"); } }

Animal.java

2006-01-31T15:39:00.000-08:00

public interface Animal { public void speak(); }