What is checked exception?

The exception which is checked by the compiler at the time of compilation for smooth execution of the program is known as checked exception.
Example:
import java.io.*;
class Test{
public static void main(String[] args){
PrintWriter pw=new PrintWriter("abc.txt");
pw.println("SILAN TECHNOLOGY");
}
}
sometimes the compiler check some specific program for smooth execution at run time, so when we compile this program we will get following compile time error :

unreported exception java.lang.FileNotFoundException must be caught or declared to be thrown

JDBC-Store image in Oracle Database

It is possible that we can store images in the database by executing jdbc program with the help of PreparedStatement interface.

The setBinaryStream() method of PreparedStatement is used to set Binary information into the parameterIndex.

For example:

CREATE TABLE user  

(

id varchar2(100),

name varchar2(100),

image BLOB

);  

Let's write the program to store the image in the database. Here we are using e:\\a.jpg for the location of image. You can change it according to the image location.

JDBC Example to store image in the database

import java.sql.*;  

import java.io.*;  

public class InsertImageDemo {  

public static void main(String[] args) throws Exception{  

Class.forName("oracle.jdbc.driver.OracleDriver");  

Connection con=DriverManager.getConnection(  

"jdbc:oracle:thin:@localhost:1521:xe","system","oracle");  

              

PreparedStatement ps=con.prepareStatement("insert into user values(?,?,?)");  

ps.setString(1,101);  

ps.setString(2,"Tapuuu");  

  

FileInputStream fin=new FileInputStream("e:\\a.jpg");  

ps.setBinaryStream(2,fin,fin.available());  

int k=ps.executeUpdate();  

System.out.println(k+" row inserted");  

          

con.close();  

}

}  

Output

1 row inserted

Note : If you see the table, record is stored in the database but image will not be shown. For this, you need to retrieve the image from the database.

What is JAVA !!!

1.    JAVA is a technology.

2.    Java is an OOP language.

3.    JAVA is a Platform.

Note : A Platform is hardware & software environment where we execute our java program. JAVA is itself a platform, bcz JAVA has it's own JRE(Java Runtime Environment).

How to convert ArrayList to String array in Java.

ArrayListExample1.java

package java8s;

import java.util.*;

public class ArrayListExample1 {

    public static void main(String[] args) {

        List al = new ArrayList<String>();

         

        al.add("First");

        al.add("Second");

        al.add("Third");

        al.add("Fourth");

        al.add("Fivth");

     

        String[] s1 = new String[al.size()];

        al.toArray(s1);

     

        for(String s2 : s1)

        System.out.println(s2);

    }

}

Output:

First

Second

Third

Fourth

Fivth

How to avoid duplicates from List / ArrayList

Hii frnds…this is the question that I have faced many times in interview, very popular frequently asked question. Let’s see in detail.

ArrayListExample.java

package java8s;

import java.util.*;

public class ArrayListExample {

          public static void main(String[] args) {

                  

                  

                                      ArrayList al = new ArrayList();

                    

                                            al.add("First");

                                            al.add("Second");

                                            al.add("Third");

                                            al.add("First");     //Duplicate

                                            al.add("First");     //Duplicate

                    

                                          

                                              ArrayList al1 = new ArrayList(new HashSet(al));     

                    

                                           // ArrayList al2 = new ArrayList(new LinkedHashSet(al));     

                    

                                           Iterator it= al1.iterator();

                                           while(it.hasNext())

                                           {

                                                 System.out.println(it.next());

                                           }

                    

                             }

                  

          }

Output:

Second

Third

First 

JAVA Program to check whether a given string is palindrome or not without taking the concept of reverse

.import java.util.*;
class StringPalindrome {

public static void main(String[] args)
{
String str;
int l,c=0;
Scanner s= new Scanner(System.in);
System.out.println("enter a string");
str= s.nextLine();
l=str.length();
for(int i=0;i<(l-1)/2; i++)
{
if(str.charAt(i)==str.charAt(l-1-i))
{
continue;
}
else
{
c++;
}
}
if(c==0)
System.out.println("the given string is a pallindrome");
else
System.out.println("the given string is a not pallindrome");

}

}

Output
enter a string
katak
the given string is pallindrome

Interface in JAVA 8(JDK 1.8 version)

It is possible to define method inside the interface by implementing default method or static method in JAVA 8.

Example1: using default method:

package test;

interface A{

default void show()

{

     System.out.println("java");

}

}

class B implements A

{

    

}

class InterfaceExample1

{

     public static void main(String[] args)

     {

          B obj=new B();

          obj.show();

     }

}

Output

java

Example2: Using static method:

package test;

interface A{

static void show()

{

    System.out.println("java");

}

}

class InterfaceExample2

{

    public static void main(String[] args)

    {

        A.show();

    }

}

Output

java