Java complete note up to now 




for previous notes   click here

JAVA NOTES 

 


How to write java program

import statements;
class class_name;
{
public static.void main(String args[ ])
{
declaration of variable;
}
}

   Sample program


import java.lang.*;
class Demo{
public static void main(String args[ ]){
System.out.println("Welcome, Hai);
}
}


• The class which contain main method it is given as a program name.
• javac program_name.java -------> For compiling a java program.
Example: javac Demo.java
• java program_name -------> For Running of the java program.
Example java Demo
• Default package: import java.lang.*;


Java program


1) To calculate Simple interest at compile time
package si;
public class SI {
  public static void main(String[] args) {
   double p=25000.00, t=2.5, r=2.00;
   double si=p*r*t/100;
   System.out.println("Principle amount:"+p);
   System.out.println("Time Duration :"+t);
   System.out.println("Rate of Intrest:"+r);
   System.out.println("Simple Interest is:"+si);
  }
}


• There are 3 ways to read value from the user
1) Input stream Reader
2) Scanner
3) Console

Syntax of Scanner
import.java.util.Scanner; or
import.java.util.*;
Create an object for Scanner--
Scanner object_name = new Scanner(System.in);
Eg: Scanner sc=new Scanner(System.in);
To read the value from user we use appropriate method on scanner object:
Datatype                    Method
int                                 nextInt( )
Float                            nextFloat( )   
Double                        nextDouble( )     
String                          next( )     For single word   
String                          nextLine( )  For line
Boolen                         nextBoolen( )
Eg. sc.nextInt();
sc.nextDoublr();
2) WAP to calculate Simple Intrest take values from user :-

package si;
import java.util.Scanner;
public class SI {
  public static void main(String[] args) {
   double p, t, r;
   Scanner sc=new Scanner(System.in);
  System.out.println("Enter Principle amount:");
   p=sc.nextDouble();
  System.out.println("Emter Time Duration :");
   t=sc.nextDouble();
  System.out.println("Enter Rate of Intrest:");
   r=sc.nextDouble();
   double si=p*t*r/100;
  System.out.println("Simple Interest is:"+si);
   sc.close();
  }
  }
3) WAP to read 2 integer values from user and display their sum, Multiple, division & (%)division.

package si;
import java.util.Scanner;
public class Arithmetic {
  public static void main(String[] args) {
  int a,b,c;
   Scanner sc=new Scanner(System.in);
  System.out.println("Enter a & b value:");
   a=sc.nextInt();
   b=sc.nextInt();
   c=a+b;
  System.out.println("Sum is:"+c);
   c=a*b;
  System.out.println("Multiple is:"+c);
   double d=a/b*1.0;
  System.out.println("Division is:"+d);
   c=a%b;
  System.out.println("Modular is:"+c);
   sc.close();
  }
  }


Homework
1) WAP to compute average of given 3 nos.
2) WAP to compute area of circle for given radius r.
3) WAP to display student details such as Name, Age, Marks, of 3 subject and percentage of marks.