Computer's current date, month, year, days of the week

class today
{
  public static void main(String args[])
  {
    //Today's date, month, year, days of the week
    String days[]={"Sun","Mon","Tue","Wed","Thu","Fri","Sat"};
    java.util.Date d1=new java.util.Date();
    System.out.println(d1.getDate());
    System.out.println(d1.getMonth()+1);
    System.out.println(d1.getYear()+1900);
    System.out.println(days[d1.getDay()]);
  }
}

Fahrenheit to Centigrade

// To find the equivalent
// degree in celcius
// for the fahrenheit degree
// from command line arguments
class circle
{
  public static void main(String args[])
  {
    double f,c;
    f=Double.parseDouble(args[0]);
    c=5/9.0*(f-32);
   
    System.out.println(c+"(C)= "+f+"(F)");
  }
}

To find the area and circurference of a circle whose radius is accepted from command line arguments

// To find the area and
// circurference of a circle
// whose radius is accepted
// from command line arguments
class circle
{
  public static void main(String args[])
  {
    double r,a,c;
    r=Double.parseDouble(args[0]);
    a=Math.PI*r*r;
    c=2*Math.PI*r;
    System.out.println("Area = "+a);
    System.out.println("Circurference = "+c);
  }
}

sum of .......

//sum of 1 to 100
int i,s=0;
for(i=1;i<=100;i++)
s=s+i;

//s contain 5050 which is sum of 1 to 100

//sum of 2+4+6+8+...+100
int i,s=0;
for(i=2;i<=100;i+=2)
s=s+i;

//s contain sum of 2+4+6+8+...+100

//sum of 3+7+11+15+...+79
int i,s=0;
for(i=3;i<=79;i+=4)
s=s+i;

//s contain sum of 3+7+11+15+...+79 

sum of 1+4+9+16+25+36+49+64+81+100

//sum of 1+4+9+16+25+36+49+64+81+100
int i,s=0;
for(i=1;i<=10;i++)
s=s+i*i;

//s contain sum of 1+4+9+16+25+36+49+64+81+100

integer ----> decimal, binary, octal, hexadecimal printing

// integer decimal, binary, octal, hexadecimal printing
int n=245;
String st1,st2,st3,st4;
st1=""+n;
st2=Integer.toBinaryString(n);
st3=Integer.toOctalString(n);
st4=Integer.toHexString(n);
System.out.println(st1);
System.out.println(st2);
System.out.println(st3);
System.out.println(st4);

Standard Dialog Boxes

int response=JOptionPane.showConfirmDialog(null,"Delete Files?");

response=JOptionPane.showConfirmDialog(null,

                             "Error Reading Files?",

                             "File Input Error",

                             JOptionPane.YES_NO_OPTION,

                             JOptionPane.ERROR_MESSAGE);  

String resp;

resp=JOptionPane.showInputDialog(null,"Enter your Name");

JOptionPane.showMessageDialog(null,

                              "The message you want to expose",

                              "Message Title",

                              JOptionPane.WARNING_MESSAGE);