Article Categories
- All Categories
-
Data Structure
-
Networking
-
RDBMS
-
Operating System
-
Java
-
MS Excel
-
iOS
-
HTML
-
CSS
-
Android
-
Python
-
C Programming
-
C++
-
C#
-
MongoDB
-
MySQL
-
Javascript
-
PHP
-
Economics & Finance
Java Articles
Page 372 of 450
How to convert InputStream object to a String in Java?
Java provides I/O Streams to read and write data where, a Stream represents an input source or an output destination which could be a file, i/o devise, other program etc.There are two types of streams available −InputStream − This is used to read (sequential) data from a source.OutputStream − This is used to write data to a destination.FileInputStreamThis class reads the data from a specific file (byte by byte). It is usually used to read the contents of a file with raw bytes, such as images.Converting an InputStream object to StringYou can convert an InputStream Object int to a String ...
Read MoreWhat is a Stream and what are the types of Streams and classes in Java?
Java provides I/O Streams to read and write data where, a Stream represents an input source or an output destination which could be a file, i/o devise, other program etc.In general, a Stream will be an input stream or, an output stream.InputStream − This is used to read data from a source.OutputStream − This is used to write data to a destination.Based on the data they handle there are two types of streams −Byte Streams − These handle data in bytes (8 bits) i.e., the byte stream classes read/write data of 8 bits. Using these you can store characters, videos, ...
Read MoreWhat is the use of in flush() and close() methods of BufferedWriter class in Java?
The BufferedWriter class of Java is used to write stream of characters to the specified destination (character-output stream). It initially stores all the characters in a buffer and pushes the contents of the buffer to the destination, making the writing of characters, arrays and Strings efficient.You can specify the required size of the buffer at the time of instantiating this class.The flush() methodWhile you are trying to write data to a Stream using the BufferedWriter object, after invoking the write() method the data will be buffered initially, nothing will be printed.The flush() method is used to push the contents of ...
Read MoreWhy does Java strictly specify the range and behavior of its primitive types?
Java provides various datatypes to store various data values. It provides 7 primitive datatypes (stores single values) namely, boolean, byte, char, short, int, long, float, double.Java strictly specifies range and behaviors of all the primitive datatypes. Making the users choose the required datatypes based on the application thus reducing the unused occupancy of memory.For example, if you need to store an integer constant of single digit using integer would be a waste of memory instead, you can use byte type since 8 bits would be necessary to store it.ExampleFollowing Java example lists out the ranges of the primitive datatypes.public class ...
Read MoreList out the default values of numeric and non-numeric primitive data types in Java?
When you create instance variables in Java you need to initialize them, else the compiler will initialize on your behalf with default values which are −byte: 0short: 0int: 0long: 0float: 0.0double: 0.0boolean: falsestring: nullExampleIn the following Java program prints the default values of the numeric and non-numeric primitive variables in java.public class DefaultValues { byte byteVariable; short shortVariable; int intVariable; long longVaraible; float floatVariable; double doubleVariable; boolean boolVariable; String stringVariable; public static void main(String args[]){ DefaultValues obj = new DefaultValues(); System.out.println("Default values of numeric variables ...
Read MoreHow to call the constructor of a superclass from a constructor in java?
Whenever you inherit/extend a class, a copy of superclass’s members is created in the subclass object and thus, using the subclass object you can access the members of both classes.ExampleIn the following example we have a class named SuperClass with a method with name demo(). We are extending this class with another class (SubClass).Now, you create an object of the subclass and call the method demo().class SuperClass{ public void demo() { System.out.println("demo method"); } } public class SubClass extends SuperClass { public static void main(String args[]) { SubClass obj = new ...
Read MoreJava ResultSet previous() method with example
When we execute certain SQL queries (SELECT query in general) they return tabular data.The java.sql.ResultSet interface represents such tabular data returned by the SQL statements.i.e. the ResultSet object holds the tabular data returned by the methods that execute the statements which quires the database (executeQuery() method of the Statement interface in general).The ResultSet object has a cursor/pointer which points to the current row. Initially this cursor is positioned before first row.The previous() method of the ResultSet interface moves the pointer of the current (ResultSet) object to the previous row, from the current position.This method returns a boolean value specifying whether ...
Read MoreJava ResultSet moveToInsertRow() method with example
When we execute certain SQL queries (SELECT query in general) they return tabular data.The java.sql.ResultSet interface represents such tabular data returned by the SQL statements.i.e. the ResultSet object holds the tabular data returned by the methods that execute the statements which quires the database (executeQuery() method of the Statement interface in general).The ResultSet object has a cursor/pointer which points to the current row. Initially this cursor is positioned before first row.The insertRow is a special row of the ResultSet in JDBC, it is associated with the updatable ResultSet objects. In it you can construct a new Row calling the UpdateXXX() ...
Read MoreWhat is ResultSet holdability in JDBC?
ResultSet holdability determines whether the ResultSet objects (cursors) should be closed or held open when a transaction (that contains the said cursor/ ResultSet object) is committed using the commit() method of the Connection interface.You can set the ResultSet holdability using the setHoldability() method of the Connection interface.con.setHoldability(ResultSet.CLOSE_CURSORS_AT_COMMIT);The ResultSet interface provides two values to specify the holdability of a ResultSet namely CLOSE_CURSORS_AT_COMMIT and, HOLD_CURSORS_OVER_COMMIT.Let us create a table with name MyPlayers in MySQL database using CREATE statement as shown below −CREATE TABLE MyPlayers( ID INT, First_Name VARCHAR(255), Last_Name VARCHAR(255), Date_Of_Birth date, Place_Of_Birth VARCHAR(255), Country VARCHAR(255), ...
Read MoreJava Connection commit() method with example
The commit() method of the Connection interface saves all the modifications made since the last commit.con.save()If any issue occurs after the commit you can revert all the changes done till this commit by invoking the rollback() method.Con.rollback()To commit a transactionRegister the driver using the registerDriver() method of the DriverManager class as −//Registering the Driver DriverManager.registerDriver(new com.mysql.jdbc.Driver());Get the connection using the getConnection() method of the DriverManager class as −//Getting the connection String url = "jdbc:mysql://localhost/mydatabase"; Connection con = DriverManager.getConnection(url, "root", "password");Turn off the auto-commit using the setAutoCommit() method as −//Setting the auto commit false con.setAutoCommit(false);Commit the transaction using the commit() method as −con.commit();Let us create a table with ...
Read More