Java Class 6 | Java Class 6 |Threads in Java| Applets | Swing GUI | JDBC | Access Modifiers in Java | Java Program
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16. Threads in Java Non-Threaded Applications Threaded Applications Process based multitasking Vs Thread based multitasking Thread API in Java Creating Threads States of a Thread Synchronization for threads; static and non-static synchronized methods; blocks; concept of object and class locks Coordination between threads - wait, notify and notifyAll methods for inter-thread communication 17. Applets What are applets? Need for Applets Different ways of running an applet program Applet API hierarchy Life Cycle of an applet Even Handlers for applets, mouse events, click events 18. Swing GUI Introduction to AWT Introduction to Swing GUI Advantages of Swing over AWT Swing API Swing GUI Components Event Handlers for Swing Sample Calculator application using Swing GUI and Swing Event handling 19. JDBC What is JDBC; introduction JDBC features JDBC Drivers Setting up a database and creating a schema Writing JDBC code to connect to DB CRUD Operations with JDBC Statement types in JDBC Types of Rowset, ResultSet in JDBC 20. Access Modifiers in Java What are access modifiers? Default Protected Private Public
![Java Class 6
“Don't worry if it doesn't work right [when coding]. If
everything did, you'd be out of a job.”
Agenda
•Threads in Java
•Applets
•Swing GUI
•JDBC
•Access Modifiers in Java](https://image.slidesharecdn.com/day5-200809190135/85/Java-Class-6-Java-Class-6-Threads-in-Java-Applets-Swing-GUI-JDBC-Access-Modifiers-in-Java-Java-Program-1-320.jpg)
![Java Values 3
Main Thread
Default Thread in any Java Program
JVM uses to execute program statements
Program To Find the Main Thread
Class Current
{
public static void main(String args[])
{
Thread t=Thread.currentThread();
System.out.println(“Current Thread: “+t);
System.out.println(“Name is: “+t.getName());
}
}
Output??](https://image.slidesharecdn.com/day5-200809190135/85/Java-Class-6-Java-Class-6-Threads-in-Java-Applets-Swing-GUI-JDBC-Access-Modifiers-in-Java-Java-Program-3-320.jpg)
![Java Database Connectivity with 5 Steps
import java.sql.*;
class OracleCon{
public static void main(String args[]){
try{
//step1 load the driver class
Class.forName("com.mysql.jdbc.Driver");
//step2 create the connection object
Connection con=DriverManager.getConnection(
"jdbc:mysql://localhost:3306/sonoo","root","root");
//step3 create the statement object
Statement stmt=con.createStatement();
//step4 execute query
ResultSet rs=stmt.executeQuery("select * from emp");
while(rs.next())
System.out.println(rs.getInt(1)+" "+rs.getString(2)+" "+rs.getString(3));
//step5 close the connection object
con.close();
}catch(Exception e){ System.out.println(e);}
}
}](https://image.slidesharecdn.com/day5-200809190135/85/Java-Class-6-Java-Class-6-Threads-in-Java-Applets-Swing-GUI-JDBC-Access-Modifiers-in-Java-Java-Program-23-320.jpg)
![Statement interface
Java Values 24
1) public ResultSet executeQuery(String sql): is used to execute
SELECT query. It returns the object of ResultSet.
2) public int executeUpdate(String sql): is used to execute
specified query, it may be create, drop, insert, update, delete etc.
3) public boolean execute(String sql): is used to execute queries
that may return multiple results.
4) public int[] executeBatch(): is used to execute batch of
commands.
•The Statement interface provides methods to execute
queries with the database.
•The statement interface is a factory of ResultSet i.e. it
provides factory method to get the object of ResultSet.
•Commonly used methods of Statement interface:](https://image.slidesharecdn.com/day5-200809190135/85/Java-Class-6-Java-Class-6-Threads-in-Java-Applets-Swing-GUI-JDBC-Access-Modifiers-in-Java-Java-Program-24-320.jpg)
Java Class 6 | Java Class 6 |Threads in Java| Applets | Swing GUI | JDBC | Access Modifiers in Java | Java Program
- 1. Java Class 6 “Don't worry if it doesn't work right [when coding]. If everything did, you'd be out of a job.” Agenda •Threads in Java •Applets •Swing GUI •JDBC •Access Modifiers in Java
- 2. Java Values 2 What is a Thread? •A thread is a lightweight sub-process, the smallest unit of processing. •Multiprocessing and multithreading, both are used to achieve multitasking. •Represents a separate path of execution of a group of statements •Java is the first language to include threading within the language, rather than treating it as a facility of the OS •Video Game example 1.one thread for graphics 2.one thread for user interaction 3.one thread for networking •Server Example 1.Do various jobs 2.Handle Several Clients Advantage: 1. Easier 2. better Performance 3. Multiple task 4.Share Resource
- 3. Java Values 3 Main Thread Default Thread in any Java Program JVM uses to execute program statements Program To Find the Main Thread Class Current { public static void main(String args[]) { Thread t=Thread.currentThread(); System.out.println(“Current Thread: “+t); System.out.println(“Name is: “+t.getName()); } } Output??
- 4. Threads in Java Java Values 4 •Creating threads in Java: 1. Extend java.lang.Thread class run() method must be overridden (similar to main method of sequential program) •run() is called when execution of the thread begins •A thread terminates when run() returns •start() method invokes run() 2. Implement java.lang.Runnable interface Methods : run() , Start (), Sleep(), Wait (), Join(), getPriority() , setPriority(), notify(), notifyall(),yield(),getname(), getid(), isAlive(), currentthread(), isDaemon(),setDaemon() etc….
- 5. Life cycle of a Thread Java Values 5
- 6. New The thread is in new state if you create an instance of Thread class but before the invocation of start() method. Runnable The thread is in runnable state after invocation of start() method, but the thread scheduler has not selected it to be the running thread. Running The thread is in running state if the thread scheduler has selected it Non-Runnable (Blocked) This is the state when the thread is still alive, but is currently not eligible to run. Terminated A thread is in terminated or dead state when its run() method exits. Java Values 6
- 7. Thread Priority Each thread is assigned a default priority of Thread.NORM_PRIORITY (constant of 5). You can reset the priority using setPriority (int priority). Some constants for priorities include: o Thread.MIN_PRIORITY (1) o Thread.MAX_PRIORITY (10) Daemon thread in java is a service provider thread that provides services to the user thread. Its life depend on the mercy of user threads i.e. when all the user threads dies, JVM terminates this thread automatically. There are many java daemon threads running automatically e.g. gc, finalizer etc. setDaemon(); isDaemon() is a method used for daemon thread. Java Values 7
- 8. Thread Synchronization Java Values 8 •A shared resource may be corrupted if it is accessed simultaneously by multiple threads. •Example: two unsynchronized threads accessing the same bank account may cause conflict. • Known as a race condition in multithreaded programs. •A thread-safe class does not cause a race condition in the presence of multiple threads. •Problem : race conditions •Solution : give exclusive access to one thread at a time to code that manipulates a shared object. •It keeps other threads waiting until the object is available. •The synchronized keyword synchronizes the method so that only one thread can access the method at a time. public synchronized void xMethod() { // method body } obj T1 (enter inside obj) T2 (wait till T1 finish)
- 9. Deadlock Apart of multithreading Can occur when a thread is waiting for an object lock, that is acquired by another thread and second thread is waiting for an object lock that is acquired by first thread Since, both threads are waiting for each other to release the lock, the condition is called deadlock Preventing Deadlock Deadlock can be easily avoided by resource ordering. With this technique, assign an order on all the objects whose locks must be acquired and ensure that the locks are acquired in that order. Example: Thread 1: lock A lock B Thread 2: wait for A lock C(when A is locked) Thread 3: wait for A wait for B wait for C Java Values 9
- 10. Inter-thread communication in Java Inter-thread communication or Co-operation is all about allowing synchronized threads to communicate with each other. It is implemented by following methods of Object class: wait() notify() notifyAll() Java Values 10 wait() sleep() wait() method releases the lock sleep() method doesn't release the lock. is the method of Object class is the method of Thread class is the non-static method is the static method is the non-static method is the static method should be notified by notify() or notifyAll() methods after the specified amount of time, sleep is completed.
- 11. Applets Applet is a special type of program that is embedded in the webpage to generate the dynamic content. It runs inside the browser and works at client side. Advantage of Applet – It works at client side so less response time. – Secured – It can be executed by browsers running under many plateforms, including Linux, Windows, Mac Os etc. Drawback of Applet – Plugin is required at client browser to execute applet. Java Values 11
- 12. public void init(): is used to initialized the Applet. It is invoked only once. public void start(): is invoked after the init() method or browser is maximized. It is used to start the Applet. public void stop(): is used to stop the Applet. It is invoked when Applet is stop or browser is minimized. public void destroy(): is used to destroy the Applet. It is invoked only once. public void paint(Graphics g): is used to paint the Applet. It provides Graphics class object that can be used for drawing oval, rectangle, arc etc. Lifecycle of Java Applet Java values
- 13. How to run an Applet? There are two ways to run an applet By html file. By appletViewer tool (for testing purpose). Html file Example: import java.applet.Applet; import java.awt.Graphics; public class First extends Applet{ public void paint(Graphics g){ g.drawString("welcome",150,150); } } <html> <body> <applet code="First.class" width="300" height="300"> </applet> </body> </html> Java Values 13 Output?
- 14. Swing GUI What is Java Swing ? • Part of the Java Foundation Classes (JFC) • Provides a rich set of GUI components. • Used to create a Java program with a graphical user interface (GUI) Features Of Swing 1) Java Look and Feel 2) Data Transfer 3) Internationalization and Localization 4) Accessibility 5) System Tray Icon Support Java Values 14
- 15. Java Swing Components… • Top Level Containers • General Purpose Containers • Special Purpose Containers • Basic Controls • Un-editable Information Displays • Interactive Displays of Highly Formatted Information Java Values 15
- 16. Top Level Containers • Window -Dialog -Frame Special Purpose Containers • Internal Frame • Layered Pane • Root Pane Java Values 16
- 17. Basic Controls • Buttons • Combo Box • List • Menu Java Values 17
- 18. Uneditable Information Displays • Label • Progress Bar Java Values 18 Interactive Displays of Highly Formatted Information
- 19. Java Values 19 Java Layout Management... 1) BorderLayout 2) FlowLayout 3) GridBagLayout 4) GridLayout Java Events Handling… button Action listener ActionEvent •Types of Event Listeners 1) ActionListener 2) WindowListener 3) MouseListener 4) MouseMotionListener 5) ComponentListener
- 20. Implementing an Event Handler • Implement the methods in the listener interface to handle the event. Conclusion • You can use any helpful tools out there that are for Java development like eclipse IDE, NetBeans IDE. We will see all the swing component Examples while doing Desktop application using Netbeans IDE. Java Values 20
- 21. JDBC Java Values 21 JDBC stands for Java Database Connectivity. JDBC is a Java API to connect and execute the query with the database. It is a part of JavaSE (Java Standard Edition). JDBC API uses JDBC drivers to connect with the database. Four types of JDBC drivers 1. JDBC-ODBC Bridge Driver, 2. Native Driver, 3. Network Protocol Driver, and 4. Thin Driver
- 22. Why Should We Use JDBC Before JDBC, ODBC API was the database API to connect and execute the query with the database. But, ODBC API uses ODBC driver which is written in C language (i.e. platform dependent and unsecured). That is why Java has defined its own API (JDBC API) that uses JDBC drivers (written in Java language). We can use JDBC API to handle database using Java program and can perform the following activities: 1. Connect to the database 2. Execute queries and update statements to the database 3. Retrieve the result received from the database. Java Values 22
- 23. Java Database Connectivity with 5 Steps import java.sql.*; class OracleCon{ public static void main(String args[]){ try{ //step1 load the driver class Class.forName("com.mysql.jdbc.Driver"); //step2 create the connection object Connection con=DriverManager.getConnection( "jdbc:mysql://localhost:3306/sonoo","root","root"); //step3 create the statement object Statement stmt=con.createStatement(); //step4 execute query ResultSet rs=stmt.executeQuery("select * from emp"); while(rs.next()) System.out.println(rs.getInt(1)+" "+rs.getString(2)+" "+rs.getString(3)); //step5 close the connection object con.close(); }catch(Exception e){ System.out.println(e);} } }
- 24. Statement interface Java Values 24 1) public ResultSet executeQuery(String sql): is used to execute SELECT query. It returns the object of ResultSet. 2) public int executeUpdate(String sql): is used to execute specified query, it may be create, drop, insert, update, delete etc. 3) public boolean execute(String sql): is used to execute queries that may return multiple results. 4) public int[] executeBatch(): is used to execute batch of commands. •The Statement interface provides methods to execute queries with the database. •The statement interface is a factory of ResultSet i.e. it provides factory method to get the object of ResultSet. •Commonly used methods of Statement interface:
- 25. Java Values 25 JDBC RowSet •The instance of RowSet is the java bean component because it has properties and java bean notification mechanism. •It is introduced since JDK 5. •It is the wrapper of ResultSet. •It holds tabular data like ResultSet but it is easy and flexible to use. Advantage of RowSet The advantages of using RowSet are given below: •It is easy and flexible to use •It is Scrollable and Updatable by default
- 26. Java Values 26 Statement PreparedStatement CallableStatement It is used to execute normal SQL queries. It is used to execute parameterized or dynamic SQL queries. It is used to call the stored procedures. It is preferred when a particular SQL query is to be executed only once. It is preferred when a particular query is to be executed multiple times. It is preferred when the stored procedures are to be executed. You cannot pass the parameters to SQL query using this interface. You can pass the parameters to SQL query at run time using this interface. You can pass 3 types of parameters using this interface. They are – IN, OUT and IN OUT. This interface is mainly used for DDL statements like CREATE, ALTER, DROP etc. It is used for any kind of SQL queries which are to be executed multiple times. It is used to execute stored procedures and functions. The performance of this interface is very low. The performance of this interface is better than the Statement interface (when used for multiple execution of same query). The performance of this interface is high
- 27. Access Modifiers in Java The access modifiers in Java specifies the accessibility or scope of a field, method, constructor, or class. We can change the access level of fields, constructors, methods, and class by applying the access modifier on it. Private: The access level of a private modifier is only within the class. It cannot be accessed from outside the class. Default: The access level of a default modifier is only within the package. It cannot be accessed from outside the package. If you do not specify any access level, it will be the default. Protected: The access level of a protected modifier is within the package and outside the package through child class. If you do not make the child class, it cannot be accessed from outside the package. Public: The access level of a public modifier is everywhere. It can be accessed from within the class, outside the class, within the package and outside the package. Java Values 27
- 28. Access Modifiers in Java There are many non-access modifiers, such as static, abstract, synchronized, native, volatile, transient, etc. A class cannot be private or protected except nested class. Java Values 28 Access Modifier within class within package outside package by subclass only outside package Private Y N N N Default Y Y N N Protected Y Y Y N Public Y Y Y Y
- 29. Summary Threads in Java Process , Thread , Lifecycle of thread, Multithread, communication between thread, Synchronization, priority Daemon thread etc Applets what is applet, life cycle , and example and uses. Swing GUI Component, events, used and advantage JDBC Introduction, features,Drivers,Writing JDBC code to connect to DB,CRUD Operations, Statement types ,Rowset, ResultSet Access Modifiers in Java Java Values 29
- 30. Java Values 30 Thank you !!! GitHub Repository : https://github.com/eewsagar YouTube: https://youtu.be/TBpu4Tlu7Q8 For any question please feel free to comment. Never Assume Clear it !!!