| Types java app |
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| Data Types and Operators |
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| (Primitive Data Types) |
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| (Non-Primitive Data Types) |
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| Control Flow Statements |
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| Conditional Statements |
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| Looping Statements |
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| Branching Statements |
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| Object-Oriented Programming (OOP) |
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| Classes and Objects |
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| Inheritance |
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| Polymorphism |
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| Encapsulation |
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| Abstraction |
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| Exception Handling |
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| Introduction to Exceptions |
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| Collections Framework |
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| Overview of Collections |
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| Commonly Used Collections |
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| Iterators |
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| Java I/O |
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| File Handling |
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| Serialization |
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| Multithreading |
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| Introduction to Threads |
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| Thread Synchronization |
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| GUI Programming with Swing |
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| Introduction to Swing |
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| Event Handling |
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| Advanced Topics |
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| Java Database Connectivity (JDBC) |
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| JAVA CODE |
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Java Basics
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Working with Objects
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Arrays, Conditionals, and Loops
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Creating Classes and Applications in Java
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More About Methods
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Java Applet Basics
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Graphics, Fonts, and Color
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Simple Animation and Threads
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More Animation, Images, and Sound
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Managing Simple Events and Interactivity
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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
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Exceptions
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Multithreading
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Streams and I/O
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Using Native Methods and Libraries
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Under the Hood
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Java Programming Tools
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Working with Data Structures in Java
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Advanced Animation and Media
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Fun with Image Filters
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Client/Server Networking in Java
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Emerging Technologies
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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
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In Java, try, catch, and finally blocks are used for exception handling. They allow you to gracefully handle runtime errors and ensure that certain code is executed regardless of whether an exception occurs. Here’s a detailed explanation of each component:
try Block
The try block is used to enclose the code that might throw an exception. It’s the code you want to monitor for exceptions. The syntax is:
try {
// Code that might throw an exception
}
catch Block
The catch block is used to handle the exception that occurs in the try block. You can have multiple catch blocks to handle different types of exceptions. The syntax is:
catch (ExceptionType1 e1) {
// Handle exception of type ExceptionType1
} catch (ExceptionType2 e2) {
// Handle exception of type ExceptionType2
}
finally Block
The finally block contains code that will always be executed after the try block, regardless of whether an exception was thrown or not. It’s typically used for cleanup activities, such as closing files or releasing resources. The syntax is:
finally {
// Code to be executed regardless of an exception
}
Example
Here’s a full example demonstrating the use of try, catch, and finally blocks:
public class ExceptionExample {
public static void main(String[] args) {
try {
int[] numbers = {1, 2, 3};
System.out.println(numbers[5]); // This will throw ArrayIndexOutOfBoundsException
} catch (ArrayIndexOutOfBoundsException e) {
System.out.println("Array index is out of bounds!");
} catch (Exception e) {
System.out.println("An exception occurred: " + e.getMessage());
} finally {
System.out.println("This will always be executed.");
}
}
}
Key Points
- Single
tryBlock: There can be only onetryblock associated with multiplecatchblocks. - Multiple
catchBlocks: You can have multiplecatchblocks to handle different types of exceptions. Eachcatchblock is an exception handler that handles the type of exception indicated by its argument. - Order of
catchBlocks: When multiplecatchblocks are used, the order matters. The more specific exception should be caught first, and the more general ones should come later. For example,catch (FileNotFoundException e)should come beforecatch (IOException e)becauseFileNotFoundExceptionis a subclass ofIOException. - Finally Block: The
finallyblock is optional, but it is often used for resource cleanup. Code in thefinallyblock will execute even if an exception is thrown or if there is areturnstatement in thetryorcatchblock. - Resource Management: From Java 7 onwards, the try-with-resources statement was introduced, which is a special form of the
trystatement that ensures resources are closed after thetryblock exits. Resources are objects that must be closed after the program is finished with them. The try-with-resources statement ensures that each resource is closed at the end of the statement. Any object that implementsjava.lang.AutoCloseable, which includes all objects which implementjava.io.Closeable, can be used as a resource.
Example of Try-With-Resources
public class TryWithResourcesExample {
public static void main(String[] args) {
try (BufferedReader br = new BufferedReader(new FileReader("file.txt"))) {
System.out.println(br.readLine());
} catch (IOException e) {
System.out.println("IOException occurred: " + e.getMessage());
}
}
}
In this example, the BufferedReader resource is closed automatically at the end of the try block. This approach simplifies resource management and helps to avoid resource leaks.
Understanding try, catch, and finally blocks is fundamental to writing robust Java applications that handle errors gracefully and perform necessary cleanup operations.
