Saturday 2 March 2013

EXAMPLE PROGRAMS


EXAMPLE-1
/* A program on instance variables.
   Call this file Demo1.java
*/
class B {
  double a;
  double b;
  double c;
}

// This class declares an object of type B
class Demo1 {
  public static void main(String args[]) {
    B bb = new B ();
    double v;

    // assign values to b instance variables
    bb.a= 10;
    bb.b = 20;
    bb.c = 15;

    // compute
    v=    bb.a *    bb.b *    bb.c;
    System.out.println("v value" + v);
  }
}

OUTPUT
C:\SATYA>javac Demo1.java
C:\SATYA>java Demo1
C:\satya>
V value is 3000.0
C:\satya>

EXAMPLE-2

// This program declares two B objects.

class B {
  double a;
  double b;
  double c;

}
 
class Demo2 {
  public static void main(String args[]) {
        B bb1 = new B ();

        B bb2 = new B ();
    double v;

    // assign values to bb1's instance variables
        bb1.a= 10;
    bb1.b = 20;
    bb1.c = 15;



    /* assign different values to bb2       instance variables */
    bb2.a= 1;
    bb2.b = 2;
    bb2.c = 1;


    // compute v firstbb1
    v=    bb1.a *    bb1.b *    bb1.c;
;
    System.out.println("V is " + v);

    // compute volume of second bb2
        v=    bb2.a *    bb2.b *    bb2.c;

    System.out.println("V is " + v);
  }
}
/* Here, B  uses a constructor to initialize */
class B {
  double a;
  double b;
  double c;



  // This is the constructor for B.
  B() {
    System.out.println("Constructing B");
   a = 10;
   b = 10;
    c = 10;
  }

  // compute and return v
  double v() {
    return a *b *c;
  }
}
 
class Demo6 {
  public static void main(String args[]) {
    // declare, allocate, and initialize Box objects
B bb1 = new B ();
        B bb2 = new B ();

    double v;

    // get v of first B
    v = bb1.v();
    System.out.println("V is " + v);

    // get v of second B
    v = bb2.v();
    System.out.println("V is " + v);
  }
}
OUTPUT
C:\SATYA>javac Demo2.java
C:\SATYA>java Demo2

C:\satya>
V value is 3000.0
V is 3.0

EXAMPLE-3
// This program includes a method inside the B class.
class B {
  double a;
  double b;
  double c;


  // display v of a B
  void v () {
    System.out.print("V is ");
    System.out.println(a* b * c);
  }
}
 
class Demo3 {
  public static void main(String args[]) {
        B bb1 = new B ();
        B bb2 = new B ();

    // assign values to bb1s instance variables
        bb1.a= 10;
    bb1.b = 20;
    bb1.c = 10;


    /* assign different values to bb2
       instance variables */
        bb2.a= 1;
    bb2.b = 2;
    bb2.c = 1;


    // display vof first B
   bb1.v();

    // display v of second B
    bb2.v();
  }
}
OUTPUT
C:\SATYA>javac Demo3.java
C:\SATYA>java Demo3
C:\satya>
 V is 2000.0
V is 2.0

EXAMPLE-4

// Now, v () returns the v value of a B.

class B {
  double a;
  double b;
  double c;



  // compute and return v
  double v () {
    return a * b * c;
  }
}
 
class Demo4 {
  public static void main(String args[]) {
        B bb1 = new B ();
        B bb2 = new B ();

    double v;

    // assign values to bb1's instance variables
        bb1.a= 10;
    bb1.b = 20;
    bb1.c = 10;

    /* assign different values to bb2
       instance variables */
            bb2.a= 1;
    bb2.b = 2;
    bb2.c = 3;


    // get v of first B
    v = bb1.v();
    System.out.println("V is " + v);

    // get v of second B
    v = bb2.v();
    System.out.println("V is " + v);
  }
}
OUTPUT
C:\SATYA>javac Demo4.java
C:\SATYA>java Demo4
C:\satya>
V is 2000.o
V is 6.0


EXAMPLE-5

// This program uses a parameterized method.

class B {
  double a;
  double b;
  double c;



  // compute and return v
  double v () {
    return a * b * c;
  }


  // sets dimensions of B
  Void D(double w, double h, double d) {
    a = w;
   b = h;
    c = d;
  }
}
 
class Demo5 {
  public static void main(String args[]) {
    B bb1 = new B ();
        B bb2 = new B ();

    double v;

    // initialize each B
   bb1.D(10, 20, 15);
    bb2.D(3, 6, 9);   

    // get v of first B
    v = bb1.v();
    System.out.println("V is " + v);

    // get v of second B
    v = bb2.v();
    System.out.println("V is " + v);
  }
}
OUTPUT
C:\SATYA>javac Demo5.java
C:\SATYA>java Demo5

C:\satya>
V is 30000.0
V is 162.0


EXAMPLE-6

/* Here, B  uses a constructor to initialize */
class B {
  double a;
  double b;
  double c;



  // This is the constructor for B.
  B() {
    System.out.println("Constructing B");
   a = 10;
   b = 10;
    c = 10;
  }

  // compute and return v
  double v() {
    return a *b *c;
  }
}
 
class Demo6 {
  public static void main(String args[]) {
    // declare, allocate, and initialize Box objects
B bb1 = new B ();
        B bb2 = new B ();

    double v;

    // get v of first B
    v = bb1.v();
    System.out.println("V is " + v);

    // get v of second B
    v = bb2.v();
    System.out.println("V is " + v);
  }
}

OUTPUT
C:\SATYA>javac Demo6.java
C:\SATYA>java Demo6
C:\satya>
 Constructing B
Constructing B
V is 1000.0
V is 1000.0

EXAMPLE-7

/* Here, B uses a parameterized constructor to  initialize */  
class B {
  double a;
  double b;
  double c;



  // This is the constructor for B.
  B(double w, double h, double d) {
    a = w;
    b = h;
    c = d;
  }

  // compute and return v
  double v() {
    return a * b * c;
  }
}
 
class Demo7 {
  public static void main(String args[]) {
    // declare, allocate, and initialize B objects
    B bb1 = new B(10, 20, 15);
    B bb2 = new B(3, 6, 9);

    double v;

    // get v of first B
    v = bb1.v();
    System.out.println("Vis " + v);

    // get v of second B
    v = bb2.v();
    System.out.println("V is " + v);
  }
}

OUTPUT
C:\SATYA>javac Demo7.java
C:\SATYA>java Demo7
C:\satya>
V is 3000.0
V is 162.0
EXAMPLE-8

// This class defines an integer stack that can hold 10 values.
class Stack {
  int stck[] = new int[10];
  int tos;
 
  // Initialize top-of-stack
  Stack() {
    tos = -1;
  }

  // Push an item onto the stack
  void push(int item) {
    if(tos==9)
      System.out.println("Stack is full.");
    else
      stck[++tos] = item;
  }

  // Pop an item from the stack
  int pop() {
    if(tos < 0) {
      System.out.println("Stack underflow.");
      return 0;
    }
    else
      return stck[tos--];
  }
}




class TestStackDemo {
  public static void main(String args[]) {
    Stack st1 = new Stack();
    Stack st2 = new Stack();

    // push some numbers onto the stack
    for(int i=0; i<10; i++) st1.push(i);
    for(int i=10; i<20; i++) st2.push(i);

    // pop those numbers off the stack
    System.out.println("Stack in mystack1:");
    for(int i=0; i<10; i++)
       System.out.println(st1.pop());

    System.out.println("Stack in mystack2:");
    for(int i=0; i<10; i++)
       System.out.println(st2.pop());
  }
}
OUTPUT
C:\SATYA>javac TestStackDemo.java
C:\SATYA>java TestStackDemo
C:\satya>
Stack in my stack1:
9
8
7
6
5
4
3
2
1
0
Stack in my stack2:
19
18
17
16
15
14
13
12
11
10
EXAMPLE-9

/* This program demonstrates the difference between   public and private */
class Access {
  int a; // default access
  public int b; // public access
  private int c; // private access

  // methods to access c
  void setc(int i) { // set c's value
    c = i;
  }
  int getc() { // get c's value
    return c;
  }
}
 
class AccessTestdemo {
  public static void main(String args[]) {
    Access ob = new Access();

    // These are OK, a and b may be accessed directly
    ob.a = 10;
    ob.b = 20;

    // This is not OK and will cause an error
//  ob.c = 100; // Error!

    // You must access c through its methods
    ob.setc(100); // OK
  
    System.out.println("a, b, and c: " + ob.a + " " +
                       ob.b + " " + ob.getc());
  }
}
OUTPUT
C:\SATYA>javac AccessTestDemo.java
C:\SATYA>java AccessTestDemo
C:\satya>
a,b and c:10  20  100
EXAMPLE-10
// Objects are passed by reference.

class TestArg {
  int a, b;

  Test(int i, int j) {
    a = i;
    b = j;
  }

  // pass an object
  void meth(Test o) {
    o.a *=  2;
    o.b /= 2;
  }
}

class CallByRefDemo {
  public static void main(String args[]) {
    TestArg ob = new TestArg(10, 20);
        System.out.println("ob.a and ob.b before call: " +
                       ob.a + " " + ob.b);
    ob.meth(ob);
    System.out.println("ob.a and ob.b after call: " +
                       ob.a + " " + ob.b);
  }}

OUTPUT
C:\SATYA>javac CallByRefDemo.java
C:\SATYA>java CallByRefDemo
C:\satya>
ob.a  and  ob.b  beforecall: 10  20
Ob.a  and  ob.b  aftercall: 20  10

EXAMPLE-11

// Simple Types are passed by value.
class CallByValue{
  void meth(int i, int j) {
    i *= 2;
    j /= 2;
  }
}

class CallByValueDemo {
  public static void main(String args[]) {
    CallByValue ob = new CallByValue ();
    int a = 150, b = 200;
   
    System.out.println("a and b before call: " +
                       a + " " + b);

    ob.meth(a, b);

    System.out.println("a and b after call: " +
                       a + " " + b);
  }
}

OUTPUT
C:\SATYA>javac InnerClassDemo2.java
C:\SATYA>java InnerclassDemo2
C:\satya>
a and b before call:150  200
A and  b after call:200  150
EXAMPLE-12

// Display all command line arguments.
class CommandLineDemo {
  public static void main(String args[]) {
    for(int i=0; i<args.length; i++)
      System.out.println("args[" + i + "]: " +
                          args[i]);
  }
}
OUTPUT
C:\SATYA>javac CallByValueDemo.java
C:\SATYA>java CallByValueDemo
              C:\satya>

EXAMPLE-13

// A simple example of recursion.
class Fact {
  // this is a recusive function
  int fact(int n) {
    int result;

    if(n==1) return 1;
    result = fact(n-1) * n;
    return result;
  }
}

class RecursionDemo {
  public static void main(String args[]) {
    Fact f = new Fact();

    System.out.println("Factorial of 3 is " + f.fact(3));
    System.out.println("Factorial of 4 is " + f.fact(4));
    System.out.println("Factorial of 5 is " + f.fact(5));
  }
}
// Demonstrate method overloading.
class OverloadDemo {
  void test() {
    System.out.println("No parameters");
  }

  // Overload test for one integer parameter.
  void test(int a1) {
    System.out.println("a1: " + a1);
  }

  // Overload test for two integer parameters.
  void test(int a, int b) {
    System.out.println("a1 and b1: " + a 1+ " " + b1);
  }

  // overload test for a double parameter
  double test(double a1) {
    System.out.println("double a: " + a1);
    return a1*a1;
  }
}
 
class Overload {
  public static void main(String args[]) {
    OverloadDemo ob = new OverloadDemo();
    double result;

    // call all versions of test()
    ob.test();
    ob.test(10);
    ob.test(10, 20);
    result = ob.test(123.2);
    System.out.println("Result of ob.test(123.2): " + result);
  }
}
OUTPUT
C:\SATYA>javac RecursionDemo.java
C:\SATYA>java RecursionDemo
C:\satya>
Factorial of 3 is 6
Factorial of 4 is 24
Factorial of  5 is 120

EXAMPLE-14

// Demonstrate an inner class.
class Out {
  int outer_x = 10;

  void test() {
    Inn inner = new Inn();
    inner.display();
  }

  // this is an innner class
  class Inn {
    void display() {
      System.out.println("display: outer_x = " + outer_x);
    }
  }
}

class InnerClassDemo {
  public static void main(String args[]) {
    Out outer = new Out();
    outer.test();
  }
}
OUTPUT
C:\SATYA>javac InnerClassDemo.java
C:\SATYA>java InnerClassDemo

C:\satya>
Display:outer_x=10

EXAMPLE-15

// This program will not compile.
class Out {
  int outer_x = 1000;

  void test() {
    Inner inner = new Inner();
    inner.display();
  }

  // this is an innner class
  class Inn {
    int y = 100; // y is local to Inner
    void display() {
      System.out.println("display: outer_x = " + outer_x);
    }
  }

  void showy() {
    System.out.println(y); // error, y not known here!
  }
}

class InnerClassDemo1 {
  public static void main(String args[]) {
    Out outer = new Out();
    outer.test();
  }
}
OUTPUT
C:\SATYA>javac InnerClassDemo1.java
C:\SATYA>java InnerclassDemo1

C:\satya>
Display:outer_x=1000
Error,y not known here!
EXAMPLE-16
// Define an inner class within a for loop.
class Out {
  int outer_x = 10;

  void test() {
    for(int i=0; i<10; i++) {
      class Inn {
        void display() {
          System.out.println("display: outer_x = " + outer_x);
        }
      }
      Inn inner = new Inn();
      inner.display();
    }
  }
}

class InnerClassDemo2 {
  public static void main(String args[]) {
    Out outer = new Out();
    outer.test();
  }
}
OUTPUT
C:\SATYA>javac InnerClassDemo2.java
C:\SATYA>java InnerclassDemo2

C:\satya>
 Display:over_x=10
Display:over_x=10
 Display:over_x=10
Display:over_x=10
Display:over_x=10
Display:over_x=10
Display:over_x=10
Display:over_x=10
Display:over_x=10
Display:over_x=10

EXAMPLE-17

// This program demonstrates the length array member.
class LengthDemo {
  public static void main(String args[]) {
    int a1[] = new int[10];
    int a2[] = {3, 5, 7, 1, 8, 99, 44, -10};
    int a3[] = {4, 3, 2, 1};

    System.out.println("length of a1 is " + a1.length);
    System.out.println("length of a2 is " + a2.length);
    System.out.println("length of a3 is " + a3.length);
  }
}

OUTPUT
C:\SATYA>javac LengthDemo.java
C:\SATYA>java LengthDemo
C:\satya>



EXAMPLE-18

// Demonstrate method overloading.
class OverloadDemo {
  void test() {
    System.out.println("No parameters");
  }

  // Overload test for one integer parameter.
  void test(int a1) {
    System.out.println("a1: " + a1);
  }

  // Overload test for two integer parameters.
  void test(int a, int b) {
    System.out.println("a1 and b1: " + a 1+ " " + b1);
  }

  // overload test for a double parameter
  double test(double a1) {
    System.out.println("double a: " + a1);
    return a1*a1;
  }
}
 
class Overload {
  public static void main(String args[]) {
    OverloadDemo ob = new OverloadDemo();
    double result;

    // call all versions of test()
    ob.test();
    ob.test(10);
    ob.test(10, 20);
    result = ob.test(123.2);
    System.out.println("Result of ob.test(123.2): " + result);
  }
}

OUTPUT
C:\SATYA>javac InnerClassDemo2.java
C:\SATYA>java InnerclassDemo2

C:\satya>

EXAMPLE-19

// Automatic type conversions apply to overloading.
class OverloadDemo {
  void test() {
    System.out.println("No parameters");
  }

  // Overload test for two integer parameters.
  void test(int a1, int b1) {
    System.out.println("a1 and b1: " + a1 + " " + b1);
  }

  // overload test for a double parameter and return type
  void test(double a1) {
    System.out.println("Inside test(double) a1: " + a1);
  }
}
 
class Overload1 {
  public static void main(String args[]) {
    OverloadDemo ob = new OverloadDemo();
    int i = 88;


    ob.test();
    ob.test(10, 20);

    ob.test(i); // this will invoke test(double)
    ob.test(123.2); // this will invoke test(double)
  }
}

OUTPUT
C:\SATYA>javac InnerClassDemo2.java
C:\SATYA>java InnerclassDemo2

C:\satya>

EXAMPLE-20
/* Here, B defines three constructors to initialize
  
class B {
  double a;
  double b;
  double c;
  // constructor used when all dimensions specified
  Box(double w, double h, double d) {
    a = w;
    b = h;
    c = d;
  }

  // constructor used when no dimensions specified
  B() {
    a = -1;  // use -1 to indicate
    b = -1; // an uninitialized
    c = -1;  // box
  }

  // constructor used when cube is created
  B(double l) {
    a = b = c = l;
  }

  // compute and return volume
  double v() {
    return a * b * c;
  }
}
 
class OverloadConsDemo {
  public static void main(String args[]) {
    // create B using the various constructors
    B aa = new B(10, 20, 15);
    B bb = new B();
    B cc = new B(7);

    double v;

    // get v of first B
    v = aa.v();
    System.out.println("V of aa  is " + v);

    // get v of second B
    v = bb.v();
    System.out.println("V of bb is " + v);

    // get volume of cube
    v = cc.v();
    System.out.println("V of cc is " + v);
  }
}

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