EXAMPLE PROGRAMS

EXAMPLE-1

/*

  Demonstrate a block of code.

 

  Call this file "Test.java"

*/

class Test {

  public static void main(String args[]) {

    int x, y;

 

    y = 20;

    // the target of this loop is a block

    for(x = 0; x<10; x++) {

      System.out.println("This is x: " + x);

      System.out.println("This is y: " + y);

      y = y - 2;

    }

  }

}

OUTPUT:

C:\SATYA>javac test.java

C:\satya>java test

This is x=0

This is y=20

This is x=1

This is y=18

This is x=2

This is y=16

This is x=3

This is y=14

This is x=4

This is y=12

This is x=5

This is y=10

This is x=6

This is y=8

This is x=7

This is y=6

This is x=8

This is y=4

This is x=9

This is y=2

C:\satya>

EXAMPLE-2

/*

   This is a simple Java program.

   Call this file "demo1.java".

*/

class Demo1 {

  // Your program begins with a call to main().

  public static void main(String args[]) {

    System.out.println("This is a simple Java program.");

  }

}

Output:

C:\satya>javac Demo1.java

C:\satya>java Demo1

This is a simple java program

C:\satya>

EXAMPLE-3

/*

   Here is another short example.

   Call this file "demo2.java".

*/class Demo2 {

public static void main(String args[]) {

    int num; // this declares a variable called num

    num = 10; // this assigns num the value 10

 

    System.out.println("This is num: " + num);

    num = num * 2;

    System.out.print("The value of num * 2 is ");

    System.out.println(num);

  }

}

Output:

C:\satya>javac Demo2.java

C:\satya>java Demo2

This is num:10

The value of num * 2 is 20

C:\satya>

EXAMPLE-4

/*

  Demonstrate the for loop.

 

  Call this file "Demo3.java".

*/

class Demo3 {

  public static void main(String args[]) {

    int x;

 

    for(x = 0; x<10; x = x+1)

      System.out.println("This is x: " + x);

  }

}

Output:

C:\satya>javac Demo3.java

C:\satya>java Demo3

This is x=0

This is x=1

This is x=2

This is x=3

This is x=4

This is x=5

This is x=6

This is x=7

This is x=8

This is x=9

C:\satya>

EXAMPLE-5

/*

  Demonstrate the if.

 

  Call this file "Sample.java".

*/

class Sample {

  public static void main(String args[]) {

    int x, y;

    x = 10;

    y = 20;

    if(x < y) System.out.println("x is less than y");

   

    x = x * 2;

    if(x == y) System.out.println("x now equal to y");

    x = x * 2;

    if(x > y) System.out.println("x now greater than y");

    // this won't display anything

    if(x == y) System.out.println("you won't see this");

  }

}

Output:

C:\satya>javac Sample.java

C:\satya>java Sample

X is less than y

X now equal to y

X now greater than y

C:\satya>

EXAMPLE-7

// Demonstrate a one-dimensional array.

class Array {

  public static void main(String args[]) {

    int month_days[];

    month_days = new int[12];

    month_days[0] = 31;

    month_days[1] = 28;

    month_days[2] = 31;

    month_days[3] = 30;

    month_days[4] = 31;

    month_days[5] = 30;

    month_days[6] = 31;

    month_days[7] = 31;

    month_days[8] = 30;

    month_days[9] = 31;

    month_days[10] = 30;

    month_days[11] = 31;

    System.out.println("April has " + month_days[3] + " days.");

  }

}

OUTPUT:

C:\SATYA>javac Array.java

C:\satya>java Array

April has 30 days

C:\satya>

EXAMPLE-8

// An improvied version of the previous program.

class Test1 {

  public static void main(String args[]) {

    int month_days[] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };

    System.out.println("April has " + month_days[3] + " days.");

  }

}

OUTPUT:

C:\SATYA>javac Test1.java

C:\satya>java Test1

April has 30 days

C:\satya>

EXAMPLE-9

// Average an array of values.

class Average {

  public static void main(String args[]) {

    double nums[] = {10.1, 11.2, 12.3, 13.4, 14.5};

    double result = 0;

    int i;

   

    for(i=0; i<5; i++)

      result = result + nums[i];

    System.out.println("Average is " + result / 5);

  }

}

OUTPUT:

C:\SATYA>javac Average.java

C:\satya>java Average

Average is 12.299999999999999

C:\satya>

EXAMPLE-10

// Demonstrate boolean values.

class Simple {

  public static void main(String args[]) {

    boolean b;

    b = false;

    System.out.println("b is " + b);

    b = true;

    System.out.pr

intln("b is " + b);

    // a boolean value can control the if statement

    if(b) System.out.println("This is executed.");

    b = false;

    if(b) System.out.println("This is not executed.");

    // outcome of a relational operator is a boolean value

    System.out.println("10 > 9 is " + (10 > 9));

  }

}

OUTPUT:

C:\SATYA>javac Simple.java

C:\satya>java Simple

b is false

b is false

This is expected

10>9 is true

C:\satya>

EXAMPLE-11

// Demonstrate char data type.

class simple2 {

  public static void main(String args[]) {

    char ch1, ch2;

    ch1 = 88;  // code for X

    ch2 = 'Y';

   

    System.out.print("ch1 and ch2: ");

    System.out.println(ch1 + " " + ch2);

  }

}

OUTPUT:

C:\SATYA>javac simple2.java

C:\satya>java simple2

Ch1 and ch2:x y

C:\satya>

EXAMPLE-12

// char variables behave like integers.

Class charDemo {

  public static void main(String args[]) {

    char ch1;

    ch1 = 'X';

    System.out.println("ch1 contains " + ch1);

    ch1++; // increment ch1

    System.out.println("ch1 is now " + ch1);

  }

}

OUTPUT:

C:\SATYA>javac charDemo.java

C:\satya>java charDemo

Ch1 contains x

Ch1 is now y

C:\satya>

EXAMPLE-13

// Demonstrate casts.

class Conver {

  public static void main(String args[]) {

    byte b;

    int i = 257;

    double d = 323.142;

   

    System.out.println("\nConversion of int to byte.");

    b = (byte) i;

    System.out.println("i and b " + i + " " + b);

    System.out.println("\nConversion of double to int.");

    i = (int) d;

    System.out.println("d and i " + d + " " + i);

    System.out.println("\nConversion of double to byte.");

    b = (byte) d;

    System.out.println("d and b " + d + " " + b);

  }

}

OUTPUT:

C:\SATYA>javac Conver.java

C:\satya>java Conver

Conversion of int to byte

i and b 257 1

Conversion of double to int

d and i 323.142 323

Conversion of double to byte

d and b 323.142 67

c:\satya>

EXAMPLE-14

// Demonstrate dynamic initialization.

class Dynamic {

    public static void main(String args[]) {

      double a = 3.0, b = 4.0;

     

      // c is dynamically initialized

      double c = Math.sqrt(a * a + b * b);

      System.out.println("Hypotenuse is " + c);

    }

}

OUTPUT:

C:\SATYA>javac Dynamic.java

C:\satya>java Dynamic

Hypotenuse is 5.0

C:\satya>

EXAMPLE-15

// Demonstrate lifetime of a variable.

class LifeTime {

  public static void main(String args[]) {

    int x;

    for(x = 0; x < 3; x++) {

      int y = -1; // y is initialized each time block is entered

      System.out.println("y iz: " + y); // this always prints -1

      y = 100;

      System.out.println("y is now: " + y);

    }

  }

}

OUTPUT:

C:\SATYA>javac LifeTime.java

C:\satya>java LifeTime

Y is:-1

Y is now:100

Y is:-1

Y is now:100

Y is:-1

Y is now:100

C:\satya>

EXAMPLE-16

// Compute distance light travels using long variables.

class Light Demo

{

  public static void main(String args[]) {

    int lightspeed;

    long days;

    long seconds;

    long distance;

    // approximate speed of light in miles per second

    lightspeed = 186000;

    days = 1000; // specify number of days here

    seconds = days * 24 * 60 * 60; // convert to seconds

    distance = lightspeed * seconds; // compute distance

    System.out.print("In " + days);

    System.out.print(" days light will travel about ");

    System.out.println(distance + " miles.");

  }

}

OUTPUT:

C:\SATYA>javac LightDemo.java

C:\satya>java LightDemo

In 1000 days light will travel about 16070400000000 miles

C:\satya>

EXAMPLE-17

// Initialize a two-dimensional array.

class Matrix {

  public static void main(String args[]) {

    double m[][] = {

      { 0*0, 1*0, 2*0, 3*0 },

      { 0*1, 1*1, 2*1, 3*1 },

      { 0*2, 1*2, 2*2, 3*2 },

      { 0*3, 1*3, 2*3, 3*3 }

    };

    int i, j;

    for(i=0; i<4; i++) {

      for(j=0; j<4; j++)

        System.out.print(m[i][j] + " ");

      System.out.println();

    }

  }

}

OUTPUT:

C:\SATYA>javac Matrix.java

C:\satya>java matrix

0.0  0.0 0.0 0.0

0.0 1.0 2.0 3.0

0.0 2.0 4.0 6.0

0.0 3.0 6.0 9.0

C:\satya>

EXAMPLE-18

class Promote {

  public static void main(String args[]) {

    byte b = 42;

    char c = 'a';

    short s = 1024;

    int i = 50000;

    float f = 5.67f;

    double d = .1234;

    double result = (f * b) + (i / c) - (d * s);

    System.out.println((f * b) + " + " + (i / c) + " - " + (d * s));

    System.out.println("result = " + result);

  }

}

OUTPUT:

C:\SATYA>javac Promote.java

C:\satya>java Promote

238.14+515-126.3616

Result=626.7784146484375

C:\satya>

EXAMPLE-19

// Demonstrate block scope.

class Scope {

  public static void main(String args[]) {

    int x; // known to all code within main

    x = 10;

    if(x == 10) { // start new scope

      int y = 20; // known only to this block

      // x and y both known here.

      System.out.println("x and y: " + x + " " + y);

      x = y * 2;

    }

    // y = 100; // Error! y not known here

    // x is still known here.

    System.out.println("x is " + x);

  }

}

OUTPUT:

C:\SATYA>javac Scope.java

C:\satya>java Scope

X and y:10 20

X is 40

EXAMPLE-20

// This program will not compile

class ScopeErr {

   public static void main(String args[]) {

     int bar = 1;

class threeDMatrix {

     {              // creates a new scope

       int bar = 2; // Compile time error -- bar already defined!

     }

   }

}

OUTPUT:

C:\SATYA>javac ScopeErr.java

C:\satya>java ScopeErr

Compile run time—bar already defined

C:\satya>

EXAMPLE-21

// Demonstrate a three-dimensional array.

Class threeDarray

  public static void main(String args[]) {

    int threeD[][][] = new int[3][4][5];

    int i, j, k;

   

    for(i=0; i<3; i++)

      for(j=0; j<4; j++)

        for(k=0; k<5; k++)

        threeD[i][j][k] = i * j * k;

    for(i=0; i<3; i++) {

      for(j=0; j<4; j++) {

        for(k=0; k<5; k++)

          System.out.print(threeD[i][j][k] + " ");

        System.out.println();

      }

      System.out.println();

    }

  }

}

OUTPUT:

C:\SATYA>javac threeDarrray.java

C:\satya>java threeDarray

0 0 0 0 0

0 0 0 0 0

0 0 0 0 0

0 0 0 0 0

0 0 0 0 0

0 1 2 3 4

0 2 4 6 8

0 3 6 9 12

0 0 0 0 0

0 2 4 6 8

 0 4 8 12 16

0 6 12 18 24

C:\satya>

EXAMPLE-22

// Manually allocate differing size second dimensions.

class TwoDAgain {

  public static void main(String args[]) {

    int twoD[][] = new int[4][];

    twoD[0] = new int[1];

    twoD[1] = new int[2];

    twoD[2] = new int[3];

    twoD[3] = new int[4];

    int i, j, k = 0;

    for(i=0; i<4; i++)

      for(j=0; j<i+1; j++) {

        twoD[i][j] = k;

        k++;

      }

    for(i=0; i<4; i++) {

      for(j=0; j<i+1; j++)

        System.out.print(twoD[i][j] + " ");

      System.out.println();

    }

  }

}

OUTPUT:

C:\SATYA>javac TwoDAgain.java

C:\satya>java TwoDAgain

0

1 2

3 4 5

6 7 8 9

C:\satya>

EXAMPLE-23

// Demonstrate a two-dimensional array.

class TwoDArray {

  public static void main(String args[]) {

    int twoD[][]= new int[4][5];

    int i, j, k = 0;

    for(i=0; i<4; i++)

      for(j=0; j<5; j++) {

        twoD[i][j] = k;

        k++;

      }

    for(i=0; i<4; i++) {

      for(j=0; j<5; j++)

        System.out.print(twoD[i][j] + " ");

      System.out.println();

    }

  }

}

OUTPUT:

C:\SATYA>javac TwoDarrray.java

C:\satya>java TwoDarray

0 1 2 3 4

5 6 7 8 9

10 11 12 13 14

15 16 17 18 19

C:\satya>

EXAMPLE-24

// Demonstrate the basic arithmetic operators.

class Basic {

  public static void main(String args[]) {

    // arithmetic using integers

    System.out.println("Integer Arithmetic");

    int a = 1 + 1;

    int b = a * 3;

    int c = b / 4;

    int d = c - a;

    int e = -d;

    System.out.println("a = " + a);

    System.out.println("b = " + b);

    System.out.println("c = " + c);

    System.out.println("d = " + d);

    System.out.println("e = " + e);

    // arithmetic using doubles

    System.out.println("\nFloating Point Arithmetic");

    double da = 1 + 1;

    double db = da * 3;

    double dc = db / 4;

    double dd = dc - a;

    double de = -dd;

    System.out.println("da = " + da);

    System.out.println("db = " + db);

    System.out.println("dc = " + dc);

    System.out.println("dd = " + dd);

    System.out.println("de = " + de);

  }

}

OUTPUT:

C:\SATYA>javac Basic.java

C:\satya>java Basic

Integer Arthimetic

a=2

b=6

c=1

d=-1

e=1

Floating point Arithmetic

da=2.0

db=6.0

dc=1.5

dd=-0.5

de=0.5

c:\satya>

EXAMPLE-25

// Demonstrate the bitwise logical operators.

class BitLogic {

  public static void main(String args[]) {

    String binary[] = {

      "0000", "0001", "0010", "0011", "0100", "0101", "0110", "0111",

      "1000", "1001", "1010", "1011", "1100", "1101", "1110", "1111"

    };

    int a = 3; // 0 + 2 + 1 or 0011 in binary

    int b = 6; // 4 + 2 + 0 or 0110 in binary

    int c = a | b;

    int d = a & b;

    int e = a ^ b;

    int f = (~a & b) | (a & ~b);

    int g = ~a & 0x0f;

    System.out.println("        a = " + binary[a]);

    System.out.println("        b = " + binary[b]);

    System.out.println("      a|b = " + binary[c]);

    System.out.println("      a&b = " + binary[d]);

    System.out.println("      a^b = " + binary[e]);

    System.out.println("~a&b|a&~b = " + binary[f]);

    System.out.println("       ~a = " + binary[g]);

  }

}

OUTPUT:

C:\SATYA>javac BitLogic.java

C:\satya>java BitLogic

a=0011

b=0110

a|b=0111

a&b=0010

a^b=0101

~a&b|a&~b=0101

~a=1100

C:\satya>

EXAMPLE-26

// Demonstrate the boolean logical operators.

Class vera

{

  public static void main(String args[]) {

    boolean a = true;

    boolean b = false;

    boolean c = a | b;

    boolean d = a & b;

    boolean e = a ^ b;

    boolean f = (!a & b) | (a & !b);

    boolean g = !a;

    System.out.println("        a = " + a);

    System.out.println("        b = " + b);

    System.out.println("      a|b = " + c);

    System.out.println("      a&b = " + d);

    System.out.println("      a^b = " + e);

    System.out.println("!a&b|a&!b = " + f);

    System.out.println("       !a = " + g);

  }

}

OUTPUT:

C:\SATYA>javac vera.java

C:\satya>java vera

a=true

b=false

a|b=true

a&b=false

a^b=true

!a&b|a&!b=true

!a=false

C:\satya>

EXAMPLE-27

// Left shifting a byte value.

class Shift {

  public static void main(String args[]) {

    byte a = 64, b;

    int i;

    i = a << 2;

    b = (byte) (a << 2);

    System.out.println("Original value of a: " + a);

    System.out.println("i and b: " + i + " " + b);

  }

}

OUTPUT:

C:\SATYA>javac Shift.java

C:\satya>java Shift

Original value of a:64

i and b:256 0

c:\satya>

EXAMPLE-28

// Unsigned shifting a byte value.

class ByteUShift {

  static public void main(String args[]) {

    char hex[] = {

      '0', '1', '2', '3', '4', '5', '6', '7',

      '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'

    };

    byte b = (byte) 0xf1;

    byte c = (byte) (b >> 4);

    byte d = (byte) (b >>> 4);

    byte e = (byte) ((b & 0xff) >> 4);

    System.out.println("              b = 0x"

      + hex[(b >> 4) & 0x0f] + hex[b & 0x0f]);

    System.out.println("         b >> 4 = 0x"

      + hex[(c >> 4) & 0x0f] + hex[c & 0x0f]);

    System.out.println("        b >>> 4 = 0x"

      + hex[(d >> 4) & 0x0f] + hex[d & 0x0f]);

    System.out.println("(b & 0xff) >> 4 = 0x"

      + hex[(e >> 4) & 0x0f] + hex[e & 0x0f]);

  }

}

OUTPUT:

C:\SATYA>javac ByteUShift.java

C:\satya>java ByteUshift

                                b=0*f1

                         b>>4=0*ff

                     b>>>4=0*ff

                 <b & 0*ff> >>4=0*0f

C:\satya>

EXAMPLE-29

// Masking sign extension.

class HexByte {

  static public void main(String args[]) {

    char hex[] = {

      '0', '1', '2', '3', '4', '5', '6', '7',

      '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'

    };

    byte b = (byte) 0xf1;

    System.out.println("b = 0x" + hex[(b >> 4) & 0x0f] + hex[b & 0x0f]);

  }}

OUTPUT:

C:\SATYA>javac HexByte.java

C:\satya>java HexByte

b=0*f1

c:\satya>

EXAMPLE-30

// Demonstrate ++ and --.

class IncDec {

  public static void main(String args[]) {

    int a = 1;

    int b = 2;

    int c;

    int d;

    c = ++b;

    d = a++;

    c++;

    System.out.println("a = " + a);

    System.out.println("b = " + b);

    System.out.println("c = " + c);

    System.out.println("d = " + d);

  }

}

OUTPUT:

C:\SATYA>javac IncDec.java

C:\satya>java IncDec

a=2

b=3

c=4

d=1

c:\satya>

EXAMPLE-31

// Demonstrate the % operator.

class Modulus {

  public static void main(String args[]) {

    int x = 42;

    double y = 42.3;

    System.out.println("x mod 10 = " + x % 10);

    System.out.println("y mod 10 = " + y % 10);

  }

}

OUTPUT

C:\Sai>javac Modulus.java

C:\Sai>java Modulus

X mod 10 = 2

Y mod 10 = 2.99999999999997

C:\Sai>

           

EXAMPLE-32

// Left shifting as a quick way to multiply by 2.

class Multi{

  public static void main(String args[]) {

    int i;

    int num = 0xFFFFFFE;

    for(i=0; i<4; i++) {

      num = num << 1;

      System.out.println(num);

    } } }

OUTPUT

C:\Sai>javac Multi.java

C:\Sai>java Multi

5367870908

1073741816

2147483632

-32

C:\Sai>

EXAMPLE-33

class Equals {

  public static void main(String args[]) {

    int a = 1;

    int b = 2;

    int c = 3;

    a |= 4;

    b >>= 1;

    c <<= 1;

    a ^= c;

    System.out.println("a = " + a);

    System.out.println("b = " + b);

    System.out.println("c = " + c);

  }}

OUTPUT

C:\Sai>javac Equals.java

C:\Sai>java Equals

   a = 3

   b = 1

   c = 6

C:\Sai>

EXAMPLE-34

// Demonstrate several assignment operators.

class op{

  public static void main(String args[]) {

    int a = 1;

    int b = 2;

    int c = 3;

    a += 5;

    b *= 4;

    c += a * b;

    c %= 6;

    System.out.println("a = " + a);

    System.out.println("b = " + b);

    System.out.println("c = " + c);

  }

}

OUTPUT

C:\Sai>javac op.java

C:\Sai>java op

   a = 6

   b = 8

   c = 3

C:\Sai>

EXAMPLE-35

// Demonstrate ?.

class Ternary {

  public static void main(String args[]) {

    int i, k;

    i = 10;

    k = i < 0 ? -i : i; // get absolute value of i

    System.out.print("Absolute value of ");

    System.out.println(i + " is " + k);

    i = -10;

    k = i < 0 ? -i : i; // get absolute value of i

    System.out.print("Absolute value of ");

    System.out.println(i + " is " + k);

  }

}

OUTPUT

C:\Sai>javac Ternary.java

C:\Sai>java Ternary

Absolute value of 10 is 10

Absolute value of -10 is -10

C:\Sai>

EXAMPLE-36

// Using break as a civilized form of goto.

Class br{

  public static void main(String args[]) {

    boolean t = true;

    first: {

      second: {

        third: {

          System.out.println("Before the break.");

          if(t) break second; // break out of second block

          System.out.println("This won't execute");

        }

        System.out.println("This won't execute");

      }

      System.out.println("This is after second block.");

    }

  }

}

OUTPUT

C:\Sai>javac br.java

C:\Sai>java br

Before the break

This is after second block.

C:\Sai

EXAMPLE-37

// This program contains an error.

class BreakErr {

  public static void main(String args[]) {

    one: for(int i=0; i<3; i++) {

      System.out.print("Pass " + i + ": ");

    }

    for(int j=0; j<100; j++) {

      if(j == 10) //break one; // WRONG

      System.out.print(j + " ");

    }

  }

}

OUTPUT

C:\Sai>javac BreakErr.java

C:\Sai>java BreakErr

Pass  0: Pass 1: Pass 2: 10

C:\Sai>

EXAMPLE-38

// Using break to exit a loop.

class BreakLoop {

  public static void main(String args[]) {

    for(int i=0; i<100; i++) {

      if(i == 10) break; // terminate loop if i is 10

      System.out.println("i: " + i);

    }

    System.out.println("Loop complete.");

  }

}

OUTPUT

C:\Sai>javac BreakLoop.java

C:\Sai>java BreakLoop

i: 0

i: 1

i: 2

i: 3

i: 4

i: 5

i: 6

i: 7

i: 8

i: 9

Loop complete.

C:\Sai>

EXAMPLE-39

// Using break to exit a while loop.

class BreakLoop2 {

  public static void main(String args[]) {

    int i = 0;

   

    while(i < 100) {

      if(i == 10) break; // terminate loop if i is 10

      System.out.println("i: " + i);

      i++;

    }

    System.out.println("Loop complete.");

  }

}

OUTPUT

C:\Sai>javac BreakLoop2.java

C:\Sai>java BreakLoop2

i: 0

i: 1

i: 2

i: 3

i: 4

i: 5

i: 6

i: 7

i: 8

i: 9

Loop complete.

C:\Sai>

EXAMPLE-40

// Using break to exit from nested loops

class Loop4 {

  public static void main(String args[]) {

    outer: for(int i=0; i<3; i++) {

      System.out.print("Pass " + i + ": ");

      for(int j=0; j<100; j++) {

        if(j == 10) break outer; // exit both loops

        System.out.print(j + " ");

      }

      System.out.println("This will not print");

    }

    System.out.println("Loops complete.");

  }

}

OUTPUT

C:\SATYA>javac Loop4.java

C:\SATYA>java Loop4

Pass 0: 0 1 2 3 4 5 6 7 8 9  Loops complete

C:\SATYA>

EXAMPLE-41

// Using the comma.

class pro{

  public static void main(String args[]) {

    int a, b;

    for(a=1, b=4; a<b; a++, b--) {

      System.out.println("a = " + a);

      System.out.println("b = " + b);

    }

  }

}

OUTPUT

C:\SATYA>javac pro.java

C:\SATYA>java pro

a = 1

b = 4

a = 2

b = 3

C:\SATYA>

EXAMPLE-43

// Demonstrate continue.

class Continue {

  public static void main(String args[]) {

    for(int i=0; i<10; i++) {

      System.out.print(i + " ");

      if (i%2 == 0) continue;

      System.out.println("");

    }

  }

}

OUTPUT

C:\SATYA>javac Continue.java

C:\SATYA>java Continue

0 1

2 3

4 5

6 7

8 9

C:\SATYA>

EXAMPLE-44

// Using continue with a label.

class ContinueLabel {

  public static void main(String args[]) {

outer: for (int i=0; i<10; i++) {

         for(int j=0; j<10; j++) {

           if(j > i) {

             System.out.println();

             continue outer;

           }

           System.out.print(" " + (i * j));

         }

       }

       System.out.println();

  }

}

OUTPUT

C:\SATYA>javac ContinueLabel.java

C:\SATYA>java ContinueLabel

0

0   1

0   2    4

0   3    6    9

0   4    8   12  16

0   5   10  15  20  25

0   6   12  18  24  30   36

0   7   14  21  28  35   42  49

0   8   16  24  32  40   48   56    64

0   9   18  27  36  45   54   63   72  81

C:\SATYA>

EXAMPLE-45

// Demonstrate the do-while loop.

class DoWhile {

  public static void main(String args[]) {

    int n = 10;

    do {

      System.out.println("tick " + n);

      n--;

    } while(n > 0);

  }

}

OUTPUT

C:\SATYA>javac DoWhile.java

C:\SATYA>java  DoWhile

Tick 10

Tick  9

Tick  8

Tick  7

Tick  6

Tick  5

Tick  4

Tick  3

Tick  2

Tick  1

C:\SATYA>

EXAMPLE-46

// Test for primes.

class Prime {

  public static void main(String args[]) {

    int num;

    boolean isPrime = true;

    num = 14;

    for(int i=2; i < num/2; i++) {

      if((num % i) == 0) {

        isPrime = false;

        break;

      }

    }

    if(isPrime) System.out.println("Prime");

    else System.out.println("Not Prime");

  }

}

OUTPUT

C:\SATYA>javac Prime.java

C:\SATYA>java  Prime

Not  Prime

C:\SATYA>

EXAMPLE-48

// Declare a loop control variable inside the for.

class ForTick1 {

  public static void main(String args[]) {

    // here, n is declared inside of the for loop

    for(int n=10; n>0; n--)

      System.out.println("tick " + n);

  }

}

OUTPUT

C:\SATYA>javac ForTick1.java

C:\SATYA>java  ForTick1

Tick 10

Tick 9

Tick 8

Tick 7

Tick 6

Tick 5

Tick 4

Tick 3

Tick 2

Tick 1

C:\SATYA>

EXAMPLE-49

// Parts of the for loop can be empty.

class ForVar {

  public static void main(String args[]) {

    int i;

    boolean done = false;

    i = 0;

    for( ; !done; ) {

      System.out.println("i is " + i);

      if(i == 10) done = true;

      i++;

    }

  }

}

OUTPUT

C:\SATYA>javac ForVar.java

C:\SATYA>java  ForVar

i  is 0

i  is 1

i  is 2

i  is 3

i  is 4

i  is 5

i  is 6

i  is 7

i  is 8

i  is 9

i  is 10

C:\SATYA>

EXAMPLE-50

// Demonstrate if-else-if statements.

class pro2{

  public static void main(String args[]) {

    int month = 4; // April

    String season;

    if(month == 12 || month == 1 || month == 2)

      season = "Winter";

    else if(month == 3 || month == 4 || month == 5)

      season = "Spring";

    else if(month == 6 || month == 7 || month == 8)

      season = "Summer";

    else if(month == 9 || month == 10 || month == 11)

      season = "Autumn";

    else

      season = "Bogus Month";

    System.out.println("April is in the " + season + ".");

  }

}

OUTPUT

C:\SATYA>javac pro2.java

C:\SATYA>java  pro2

April  is  in the Spring.

C:\SATYA>

EXAMPLE-51

// Using a do-while to process a menu selection -- a simple help system.

class Menu {

  public static void main(String args[])

    throws java.io.IOException {

    char choice;

    do {

      System.out.println("Help on:");

      System.out.println("  1. if");

      System.out.println("  2. switch");

      System.out.println("  3. while");

      System.out.println("  4. do-while");

      System.out.println("  5. for\n");

      System.out.println("Choose one:");

      choice = (char) System.in.read();

    } while( choice < '1' || choice > '5');

    System.out.println("\n");

    switch(choice) {

      case '1':

        System.out.println("The if:\n");

        System.out.println("if(condition) statement;");

        System.out.println("else statement;");

        break;

      case '2':

        System.out.println("The switch:\n");

        System.out.println("switch(expression) {");

        System.out.println("  case constant:");

        System.out.println("    statement sequence");

        System.out.println("  break;");

        System.out.println("  // ...");

        System.out.println("}");

        break;

      case '3':

        System.out.println("The while:\n");

        System.out.println("while(condition) statement;");

        break;

      case '4':

        System.out.println("The do-while:\n");

        System.out.println("do {");

        System.out.println("  statement;");

        System.out.println("} while (condition);");

        break;

      case '5':

        System.out.println("The for:\n");

        System.out.print("for(init; condition; iteration)");

        System.out.println(" statement;");

        break;

    }

  }

}

OUTPUT

C:\SATYA>javac Menu.java

C:\SATYA>java  Menu

Help on:

1. if

2. switch

3. while

4. do-while

5.  for

Choose one:  1

 

if<condition> statement;

else statement;

C:\SATYA>

EXAMPLE-52

// In a switch, break statements are optional.

Class pro1{

  public static void main(String args[]) {

    for(int i=0; i<12; i++)

      switch(i) {

        case 0:

        case 1:

        case 2:

        case 3:

        case 4:

          System.out.println("i is less than 5");

          break;

        case 5:

        case 6:

        case 7:

        case 8:

        case 9:

          System.out.println("i is less than 10");

          break;

        default:

          System.out.println("i is 10 or more.");

      }

  }

}

OUTPUT

C:\SATYA>javac pro1.java

C:\SATYA>java  pro1

i  is less than 5

i  is less than 5

i  is less than 5

i  is less than 5

i  is less than 5

i  is less than 10

i  is less than 10

i  is less than 10

i  is less than 10

i  is less than 10

i  is 10 or more

i  is 10 or more

C:\SATYA>

EXAMPLE-53

// Loops may be nested.

class Nested {

  public static void main(String args[]) {

    int i, k;

    for(i=0; i<10; i++) {

      for(k=i;k<10;k++)

        System.out.print(".");

      System.out.println();

    }

  }

}

OUTPUT

C:\SATYA>javac Nested.java

C:\SATYA>java  Nested

. . . . . . . . . . .

. . . . . . . . . .

. . . . . . . . .

. . . . . . . .

. . . . . . .

. . . . . .

. . . . .

. . . .

. . .

. .

.

C:\SATYA>

EXAMPLE-54

// The target of a loop can be empty.

class  target{

  public static void main(String args[]) {

    int i, j;

    i = 100;

    j = 200;

    // find midpoint between i and j

    while(++i < --j) ; // no body in this loop

    System.out.println("Midpoint is " + i);

  }

}

OUTPUT

C:\SATYA>javac target.java

C:\SATYA>java  target

Midpoint is 150

C:\SATYA>

EXAMPLE-55

// Demonstrate return.

class Return {

  public static void main(String args[]) {

    boolean k= true;

    System.out.println("Before the return.");

    if(k) return // return to caller

    System.out.println("This won't execute.");

  }

}

OUTPUT

Error

EXAMPLE-56

class Sample3{

  public static void main(String args[]) {

    int a, b;

    b = 4;

    for(a=1; a<b; a++) {

      System.out.println("a = " + a);

      System.out.println("b = " + b);

      b--;

    }

  }

}

OUTPUT

C:\SATYA>javac Sample3.java

C:\SATYA>java  Sample

a = 1

b = 4

a = 2

b = 3

C:\SATYA>

EXAMPLE-57

// A simple example of the switch.

Class Switch3{

  public static void main(String args[]) {

    for(int i=0; i<6; i++)

      switch(i) {

        case 0:

          System.out.println("i is zero.");

          break;

        case 1:

          System.out.println("i is one.");

          break;

        case 2:

          System.out.println("i is two.");

          break;

        case 3:

          System.out.println("i is three.");

          break;

        default:

          System.out.println("i is greater than 3.");

      }

  }

}

OUTPUT

C:\SATYA>javac Switch3.java

C:\SATYA>java  Switch3

i is zero

i is one

i is two

i is three

i is greater than 3

i is greater than 3

C:\SATYA>

EXAMPLE-58

// An improved version of the season program.

class Session{

    public static void main(String args[]) {

        int month = 4;

        String season;

        switch (month) {

          case 12:

          case 1:

          case 2:

            season = "Winter";

            break;

          case 3:

          case 4:

          case 5:

            season = "Spring";

            break;

          case 6:

          case 7:

          case 8:

            season = "Summer";

            break;

          case 9:

          case 10:

          case 11:

            season = "Autumn";

            break;

          default:

            season = "Bogus Month";

        }

        System.out.println("April is in the " + season + ".");

    }

}

OUTPUT:

C:\SATYA>javac Session.java

C:\satya>java Session

April is in the spring

C:\satya>

EXSAMPLE-59

// Demonstrate the while loop.

class Loop

  public static void main(String args[]) {

    int n = 10;

    while(n > 0) {

      System.out.println("tick " + n);

      n--;

    }

  }

}

OUTPUT:

C:\SATYA>javac Loop.java

C:\satya>java Loop

Tick 10

Tick 9

Tick 8

Tick 7

Tick 6

Tick 5

Tick 4

Tick 3

Tick 2

Tick 1

C:\satya>