| Types java app |
|---|
| Data Types and Operators |
|---|
| (Primitive Data Types) |
|---|
| (Non-Primitive Data Types) |
|---|
| Control Flow Statements |
|---|
| Conditional Statements |
|---|
| Looping Statements |
|---|
| Branching Statements |
|---|
| Object-Oriented Programming (OOP) |
|---|
| Classes and Objects |
|---|
| Inheritance |
|---|
| Polymorphism |
|---|
| Encapsulation |
|---|
| Abstraction |
|---|
| Exception Handling |
|---|
| Introduction to Exceptions |
|---|
| Collections Framework |
|---|
| Overview of Collections |
|---|
| Commonly Used Collections |
|---|
| Iterators |
|---|
| Java I/O |
|---|
| File Handling |
|---|
| Serialization |
|---|
| Multithreading |
|---|
| Introduction to Threads |
|---|
| Thread Synchronization |
|---|
| GUI Programming with Swing |
|---|
| Introduction to Swing |
|---|
| Event Handling |
|---|
| Advanced Topics |
|---|
| Java Database Connectivity (JDBC) |
|---|
| JAVA CODE |
|---|
|
Java Basics
|
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Working with Objects
|
|
Arrays, Conditionals, and Loops
|
|
Creating Classes and Applications in Java
|
|
More About Methods
|
|
Java Applet Basics
|
|
Graphics, Fonts, and Color
|
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Simple Animation and Threads
|
|
More Animation, Images, and Sound
|
|
Managing Simple Events and Interactivity
|
|
Creating User Interfaces with the awt
|
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Windows, Networking, and Other Tidbits
|
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Modifiers, Access Control, and Class Design
|
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Packages and Interfaces
|
|
Exceptions
|
|
Multithreading
|
|
Streams and I/O
|
|
Using Native Methods and Libraries
|
|
Under the Hood
|
|
Java Programming Tools
|
|
Working with Data Structures in Java
|
|
Advanced Animation and Media
|
|
Fun with Image Filters
|
|
Client/Server Networking in Java
|
|
Emerging Technologies
|
|
appendix A :- Language Summary
|
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appendix B :- Class Hierarchy Diagrams
|
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appendix C The Java Class Library
|
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appendix D Bytecodes Reference
|
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appendix E java.applet Package Reference
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appendix F java.awt Package Reference
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appendix G java.awt.image Package Reference
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appendix H java.awt.peer Package Reference
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appendix I java.io Package Reference
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appendix J java.lang Package Reference
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appendix K java.net Package Reference
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appendix L java.util Package Reference
|
Executing SQL queries in Java involves several steps, including establishing a connection to the database, creating a statement, executing the query, and processing the results. Here’s a detailed description of the process with examples:
1. Setup: Add JDBC Driver
First, you need to add the JDBC driver for your database to your project. For example, if you are using MySQL, you can add the MySQL Connector/J JAR file to your project.
2. Import Required Packages
Import the necessary JDBC packages:
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
3. Establish a Connection
Establish a connection to the database using ‘DriverManager.getConnection‘:
String url = "jdbc:mysql://localhost:3306/your_database";
String user = "your_username";
String password = "your_password";
Connection connection = null;
try {
connection = DriverManager.getConnection(url, user, password);
if (connection != null) {
System.out.println("Connected to the database!");
}
} catch (SQLException e) {
e.printStackTrace();
}
4. Create a Statement
Create a Statement object to send SQL statements to the database:
Statement statement = null;
try {
statement = connection.createStatement();
} catch (SQLException e) {
e.printStackTrace();
}
5. Execute a Query
Execute a SQL query using the executeQuery method for SELECT statements or executeUpdate for INSERT, UPDATE, and DELETE statements.
Example of a SELECT Query:
String query = "SELECT id, name, age FROM users";
ResultSet resultSet = null;
try {
resultSet = statement.executeQuery(query);
// Process the results
while (resultSet.next()) {
int id = resultSet.getInt("id");
String name = resultSet.getString("name");
int age = resultSet.getInt("age");
System.out.println("ID: " + id + ", Name: " + name + ", Age: " + age);
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
// Close the ResultSet
if (resultSet != null) {
try {
resultSet.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
Example of an INSERT Query:
String insertQuery = "INSERT INTO users (name, age) VALUES ('John Doe', 30)";
int rowsAffected = 0;
try {
rowsAffected = statement.executeUpdate(insertQuery);
System.out.println("Rows affected: " + rowsAffected);
} catch (SQLException e) {
e.printStackTrace();
}
6. Close the Connection
Finally, close the Statement and Connection objects to free up resources:
if (statement != null) {
try {
statement.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if (connection != null) {
try {
connection.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
Full Example
Here’s the complete code combining all the steps:
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class Main {
public static void main(String[] args) {
String url = "jdbc:mysql://localhost:3306/your_database";
String user = "your_username";
String password = "your_password";
Connection connection = null;
Statement statement = null;
ResultSet resultSet = null;
try {
// Establish connection
connection = DriverManager.getConnection(url, user, password);
if (connection != null) {
System.out.println("Connected to the database!");
// Create statement
statement = connection.createStatement();
// Execute SELECT query
String query = "SELECT id, name, age FROM users";
resultSet = statement.executeQuery(query);
// Process results
while (resultSet.next()) {
int id = resultSet.getInt("id");
String name = resultSet.getString("name");
int age = resultSet.getInt("age");
System.out.println("ID: " + id + ", Name: " + name + ", Age: " + age);
}
// Execute INSERT query
String insertQuery = "INSERT INTO users (name, age) VALUES ('Jane Doe', 25)";
int rowsAffected = statement.executeUpdate(insertQuery);
System.out.println("Rows affected: " + rowsAffected);
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
// Close resources
if (resultSet != null) {
try {
resultSet.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if (statement != null) {
try {
statement.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if (connection != null) {
try {
connection.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}
}
This example demonstrates how to connect to a MySQL database, execute a SELECT query to retrieve data, and execute an INSERT query to insert data into the database. Adjust the connection details and SQL queries according to your database schema and requirements.
