Skip to main content

Q) Hierarchy of Exception classes




A)
 
->RuntimeException is unchecked exception that’s why their children also coming under unchecked exception.
->super class of all exception classes is “throwable”.
->throwable has 2 sub classes
 1) Error class –very very dangerous ex: static flow
 2) Exception class
->in java applications java.long.Error class and its sub classes representing exceptions can’t be handled.
So, Errors are not handled by JVM. Only some JVM manufacturers handle those errors.
Ex: stack over flow
->Java.long.Exception and its sub classes represent abnormal events. That can be handled in java applications.

Generally
Error- the java compiler rising
Exception- the JVM rising

->java long.Exception class has two kinds of sub classes
1) unchecked exception classes
2) checked exception classes

->java.long.RuntimeException is the only sub class of Exception which is unchecked. All other sub classes of Exception classes are checked.
->All sub classes of java.long.RuntimeException also are unchecked.
->Error can coming under unchecked because can’t be handles are coming under unchecked.
->All abnormal scenarios are pre estimated that classes are developed.

Comments

Post a Comment

Popular posts from this blog

Q) Explain repeated deletion of records.

A) //RepeatedDeletion.java import java.util.Scanner; import java.sql.*; class RepeatedDeletion {        public static void main(String[] args) {               Connection con= DriverManager. getConnection ( "jdbc:odbc:prince" , "scott" , "tiger" );               PreparedStatement ps=con.PreparedStatement( "DELETE FROM ACCOUNT WHERE ACCNO=?" );               Scanner s= new Scanner(System. in );               while ( true )               {                      System. out .println( "Enter accno : " );      ...
Post a Comment
Read more

Q) Retrieving data from database?

A)   ->to retrieve the data from database we need to submit SELECT statement from JDBC application. -> executeQuery() method of statement object is used for this purpose. This method has the fallowing ResultSet executeQuery(String sql) throws SQLException Ex: ResultSet rs = st.executeQuery(“SELECT * FROM ACCOUNT”); ->objectoriented representation of tables formate data is called ResultSet object. Ao the driver created one object i.e. ResultSet object. ->object orientation representation of a table of records returned from db is nothing but “ ResultSet ” object.  
Post a Comment
Read more

Q) What is the purpose of JDBC?

A) -> Java application can do any task by making a method (function) call. ->java method calls are not understandable to database management system. They can understand only SQL statements. ->SQL statements can’t be directly used in a java application. Java compiler complains. ->therefore, we say that java environment and database environment are heterogeneous to each other. Purpose of JDBC: ->for any kind of java application to communicate with any kind of database (management system) in a standard manner, JDBC is used.
Post a Comment
Read more