[ ( 'public' | 'private' | 'protected' ) ]
  [ ( 'final' | 'volatile' ) ]
    [ 'static' ] [ 'transient' ]
      data_type field_name [ '=' expression ] ';'


class Employee
{
   String name; // The employee's name.
   double salary; // The employee's salary.
   int jobID; // The employee's job identification code (e.g., accountant, payroll clerk, manager, and so on).
}


class MyClass
{
   int fred;
}


class Employee
{
   private double salary;
}


public class Employee
{
   public String name;
}


public class Body
{
   public Eye leftEye, rightEye;
   private Heart heart;
   private Lung leftLung, rightLung;
}


public class Employee
{
   protected String name;
}


class Employee
{
   final int ACCOUNTANT = 1;
   final int PAYROLL_CLERK = 2;
   final int MANAGER = 3;

   int jobID = ACCOUNTANT;
}


class SomeClass1
{
   int i = 5;

   void print ()
   {
      System.out.println (i);
   }

   public static void main (String [] args)
   {
      SomeClass1 sc1 = new SomeClass1 ();
      System.out.println (sc1.i);
   }
}


class SomeClass2
{
   static int i = 5;

   void print ()
   {
      System.out.println (i);
   }

   public static void main (String [] args)
   {
      System.out.println (i);
   }
}


class Global
{
   static String name;
}

class UseGlobal
{
   public static void main (String [] args)
   {
      Global.name = "UseGlobal";
      System.out.println (Global.name);
   }
}


Exception in thread "main" java.lang.NoSuchMethodError: main

class Constants
{
   final int FIRST = 1;
   final static int SECOND = 2;

   public static void main (String [] args)
   {
      int iteration = SECOND;

      if (iteration == FIRST) // Compiler error.
   System.out.println ("first iteration");
   else
   if (iteration == SECOND)
   System.out.println ("second iteration");
   }
}


Listing 1. Zoo1.java

// Zoo1.java

class CircusAnimal
{
   final static int TIGER = 1;
   final static int LION = 2;
   final static int ELEPHANT = 3;
   final static int MONKEY = 4;
}

class Zoo1
{
   private int animal;

   public static void main (String [] args)
   {
      Zoo1 z1 = new Zoo1 ();
      z1.animal = CircusAnimal.TIGER;

      // Some time later ...

      if (z1.animal == CircusAnimal.TIGER)
         System.out.println ("This circus animal is a tiger!");
      else
      if (z1.animal == CircusAnimal.MONKEY)
         System.out.println ("This circus animal is a monkey!");
      else
         System.out.println ("Don't know what this circus animal is!");
   }
}



Listing 2. Zoo2.java

// Zoo2.java

class CircusAnimal
{
   static final CircusAnimal TIGER = new CircusAnimal ("Tiger");
   static final CircusAnimal LION = new CircusAnimal ("Lion");
   static final CircusAnimal ELEPHANT = new CircusAnimal ("Elephant");
   static final CircusAnimal MONKEY = new CircusAnimal ("Monkey");

   private String animalName;

   private CircusAnimal (String name)
   {
      animalName = name;
   }

   public String toString ()
   {
      return animalName;
   }
}

class Zoo2
{
   private CircusAnimal animal;

   public static void main (String [] args)
   {
      Zoo2 z2 = new Zoo2 ();
      z2.animal = CircusAnimal.TIGER;

      // Some time later ...

      if (z2.animal == CircusAnimal.TIGER)
         System.out.println ("This circus animal is a tiger!");
      else
      if (z2.animal == CircusAnimal.MONKEY)
         System.out.println ("This circus animal is a monkey!");
      else
         System.out.println ("Don't know what this circus animal is!");
   }
}


[ ( 'public' | 'private' | 'protected' ) ]
  ( [ 'abstract' ] | [ 'final' ] [ 'static' ] [ 'native' ] [ 'synchronized' ] )
    return_data_type method_name '(' [ parameter_list ] ')'
    compound_statement


class MathUtilities
{
   int sum (int limit)
   {
      System.out.println ("limit = " + limit);

      System.out.println ("total = " + total); // Compiler error.

      int total;

      for (int i = 1; i <= limit; i++)
         total += i; // Compiler error.

      System.out.println ("i = " + i); // Compiler error.

      return total; // Compiler error.
   }
}


// Compiler error
System.out.println ("total = " + total);


MathUtilities mu = new MathUtilities (); int sumTotal = mu.sum (10);


class Temperature
{
   private int degrees;

   void setDegrees (int d)
   {
      degrees = d;
   }

   int getDegrees ()
   {
      return degrees;
   }
}


class MathUtilities
{
   private int factorial (int n)
   {
      if (n == 0)
         return 1; // 0! (0 factorial) returns 1

      int product = 1;

      for (int i = 2; i <= n; i++)
         product *= i;

      return product;
   }

   int permutation (int n, int r)
   {
      return factorial (n) / factorial (n - r);
   }
}


public class Color
{
   private int color;

   public int getColor () { return color; }
}


class Employee
{
   // Several fields are declared but not shown in this example.

   protected double computeSalary ()
   {
      return hoursWorked * hourlyRate;
   }
}


class Employee
{
   private double salary;

   void setSalary (double s)
   {
      salary = s;
   }
}


class Employee
{
   private double salary;

   void setSalary (double salary)
   {
      this.salary = salary;
   }
}


class MyClass
{
   void first () { second (true); }

   void second (boolean firstFlag)
   {
      if (firstFlag)
         System.out.println ("First flag.");
      else
         System.out.println ("Second flag.");
   }
}


class AnotherClass
{
   void callSecond ()
   {
      MyClass mc = new MyClass ();
      mc.second (false);

      new MyClass ().second (false);
   }
}


class HelloGoodBye
{
   public static void main (String [] args)
   {
      new HelloGoodBye ().hello ().goodbye ();
   }

   HelloGoodBye hello ()
   {
      System.out.println ("Hello");

      return this;
   }

   void goodbye ()
   {
      System.out.println ("Goodbye");
   }
}


class Employee
{
   private static int numEmployees;

   static void setEmployeeCount (int numEmp)
   {
      numEmployees = numEmp;
   }
}


class Employee
{
   private static int numEmployees;

   static void setEmployeeCount (int numEmployees)
   {
      this.numEmployees = numEmployees; // Compiler error.
   }
}


class FirstAndSecond
{
   static void first ()
      {
      System.out.println ("first");
      second ();
   }

   static void second ()
   {
      System.out.println ("second");
   }
}


class UseFirstAndSecond
{
   public static void main (String [] args)
   {
      FirstAndSecond.first ();
      FirstAndSecond.second ();
   }
}


Listing 3. CBDemo.java

// CBDemo.java

class Employee
{
   private double salary;

   double getSalary () { return salary; }

   void setSalary (double salary) { this.salary = salary; }
}

class CBDemo
{
   public static void main (String [] args)
   {
      int v = 12;
      Employee e = new Employee ();
      e.setSalary (50000.0);

      System.out.println ("v = " + v);
      System.out.println ("e salary = " + e.getSalary ());

      changeArgs (v, e);

      System.out.println ("v = " + v);
      System.out.println ("e salary = " + e.getSalary ());
   }

   static void changeArgs (int x, Employee y)
   {
      x = 30;
      y.setSalary (30000.0);
   }
}


v = 12
e salary = 50000.0
v = 12
e salary = 30000.0


void print ()
{
   System.out.println ("Default");
}

void print (String arg)
{
   System.out.println (arg);
}


int sum (int x, int y)
{
   return x + y;
}

long sum (int x, int y)
{
   return x + y;
}


CODemo2 obj1 = new CODemo2 ();


class X
{
}


class X
{
   X ()
   {
   }
}


class X
{
   private int i;

   X (int i)
   {
      this.i = i;
   }
}

class UseX
{

   public static void main (String [] args)
   {
      X x1 = new X (2);

      X x2 = new X (); // Compiler error.
   }
}


class X
{
   int i = 5;

   X ()
   {
      System.out.println (i);
   }
}

class UseX
{
   public static void main (String [] args)
   {
      X x = new X ();
   }
}


Listing 4. Geometry.java

// Geometry.java

class Circle
{
   private int x, y, r;

   Circle ()
   {
      // System.out.println ("Before");
      this (0, 0, 1);
      System.out.println ("After");
   }

   Circle (int x, int y, int r)
   {
      this.x = x;
      this.y = y;
      this.r = r;
      }

   int getX () { return x; }
   int getY () { return y; }
   int getRadius () { return r; }
}

class Geometry
{
   public static void main (String [] args)
   {
      Circle c1 = new Circle ();
      System.out.println ("Center X = " + c1.getX ());
      System.out.println ("Center Y = " + c1.getY ());
      System.out.println ("Center Radius = " + c1.getRadius ());

      Circle c2 = new Circle (5, 6, 7);
      System.out.println ("Center X = " + c2.getX ());
      System.out.println ("Center Y = " + c2.getY ());
      System.out.println ("Center Radius = " + c2.getRadius ());
   }
}


public class NetworkConnection
{
   private static NetworkConnection singleton;

   private NetworkConnection ()
   {
      // The code in this constructor establishes the network connection.
      // This code deals with situations in which the connection is down.
   }

   public static NetworkConnection getInstance ()
   {
      if (singleton == null)
         singleton = new NetworkConnection ();

      return singleton;
   }
}


NetworkConnection nc = NetworkConnection.getInstance ();