Resources for the textbook An Introduction to JAVA Programming

Keyboard Class

import java.io.*;
 public class Keyboard {
     public static String readString() {
         BufferedReader br;
         try {
             br = new BufferedReader(new InputStreamReader(System.in));
             return br.readLine();
         } catch (Exception e) {}
         return null;
     }
     public static int readInt() {
         return Integer.parseInt(readString());
     }
     public static byte readByte() {
         return Byte.parseByte(readString());
     }
     public static short readShort() {
         return Short.parseShort(readString());
     }
     public static long readLong() {
         return Long.parseLong(readString());
     }
     public static float readFloat() {
         return Float.parseFloat(readString());
     }
     public static double readDouble() {
         return Double.parseDouble(readString());
     }
     public static char readChar() {
         return readString().charAt(0);
     }
     public static boolean readBoolean() {
         return Boolean.parseBoolean(readString());
     }
 }

EasyScanner class

import java.util.*;
public class EasyScanner {
    public static int readInt() {
        Scanner sc = new Scanner(System.in);
        int i = sc.nextInt();
        return i;
    }
    public static double readDouble() {
        Scanner sc = new Scanner(System.in);
        double d = sc.nextDouble();
        return d;
    }
    public static String readString() {
        Scanner sc = new Scanner(System.in);
        String s = sc.nextLine();
        return s;
    }
    public static char readChar() {
        Scanner sc = new Scanner(System.in);
        char c = sc.next().charAt(0);
        return c;
    }
}
EasyScanner.java

Appendix 2 – Solutions

2.1   Paper 1 – Type question

• total, num
• for loop
• public, class, int, for

2.2   Paper 2A – Type question

1. A class defines a new data type which once defined can be used to create objects of that type.
2. public class Ellipse { double radius1, radius2;double Calc_Area( ) { return (Math.PI * radius1 * radius2); } }
3. public class Shapes { public static void main (String args[]) {Ellipse e1 = new Ellipse(); Ellipse e2 = new Ellipse();e1.radius1 = 1 + Math.random() * 10; e1.radius2 = 1 + Math.random() * 10; e2.radius1 = 1 + Math.random() * 10; e2.radius2 = 1 + Math.random() * 10;System.out.println(“Ellipse 1 has radii :”+ e1.radius1 +” and ” + e1.radius2); System.out.println(“Ellipse 2 has radii :”+ e2.radius1 +” and ” + e2.radius2);System.out.println(“The area of Ellipse 1 is : ” + e1.Calc_Area()); System.out.println(“The area of Ellipse 2 is : ” + e2.Calc_Area()); } }

2.3   Paper 2B – Type question

1. A class defines a new data type which once defined can be used to create objects of that type.
2. public class Square { int length; void displayArea() { System.out.println(“Area of Square : ” + (length*length)); } void displayPerimeter() { System.out.println(“Perimiter of Square : ” + (4 * length)); } }
3. public class Shapes { public static void main (String args[]) { Square s = new Square(); s.length = 5; s.displayArea(); s.displayPerimeter(); } }

Download files (see contents of zip file below)

Code shown above

KeyboardClass.java KeyboardClass.class EasyScanner.class

Solution 1

Time.java

Solution 2

Numbers.java

Solution 3

Pizza.java

Solution 4

Calc.java UseCalc.java

Solution 5

BMI.java

Solution 6

Circle.java useCircle.java