Video:
Object hierarchy in java programming for Exceptions:
Object
- Throwable
- Exception
- IOException
- EOFException
- FileNotFoundException
- - -
- SQLException
- ClassNotFoundException
- CloneNotSupportedException
- - -
- RunTimeException
- NullPointerException
- AirthmeticException
- - -
- Error
- VirtualMachinError
- AssertionError
Diagram for exceptions classes hierarchy:
Video:
Note:
Checked exception > All exceptions are checked exceptions, except for those indicated by
Error
, RuntimeException
, and their subclasses.Unchecked exceptions > Errors and runtime exceptions are collectively known as unchecked exceptions.
Code example:
Create the new java project in Eclipse.Open the Eclipse
File > New > Java Project
Type the project name: Exceptions-In-Java-Programming
Click the next button
Click the Finish
Add the below java files:
Right click on the src folder > new > ClassType the class package name: com.exceptions.tutorialbyexample
Type the Class name: CheckedExceptionCompileTime.java
package com.exceptions.tutorialbyexample; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.IOException; public class CheckedExceptionCompileTime { public CheckedExceptionCompileTime() { // TODO Auto-generated constructor stub } public void callMe() { try { System.out.println("Inside print method"); FileInputStream objFIS = null; /** * This constructor FileInputStream(File filename) throws * FileNotFoundException which is a checked exception */ objFIS = new FileInputStream("c:/tutorialbyexample-for-exception.txt"); int i; /* * Method read() of FileInputStream class also throws a checked * exception: IOException */ while ((i = objFIS.read()) != -1) { System.out.print((char) i); } /* * The method close() closes the file input stream It throws * IOException */ objFIS.close(); } catch (FileNotFoundException e) { e.getMessage(); } catch (IOException e) { e.getMessage(); } } public static void main(String[] args) { // Creating the object of ExceptionsInJavaProgramming CheckedExceptionCompileTime obj = new CheckedExceptionCompileTime(); System.out.println("Inside main method"); obj.callMe(); } }
If not handled by try/cache or Throws then, code will not compile it:
Unhandled exception type IOException
Unhandled exception type FileNotFoundException
Right click on the src folder > new > Class
Type the class package name: com.exceptions.tutorialbyexample
Type the Class name: UnCheckedExceptionOrRunTime.java
package com.exceptions.tutorialbyexample; public class UnCheckedExceptionOrRunTime { public UnCheckedExceptionOrRunTime() { // TODO Auto-generated constructor stub } public void print() { int a = 10, b = 0, c; try { c = a / b; System.out.println("Value of c = " + c); } catch (java.lang.ArithmeticException e) { e.printStackTrace(); } catch (Exception e) { e.printStackTrace(); } } public static void main(String[] args) { // Creating the object of ExceptionsInJavaProgramming UnCheckedExceptionOrRunTime obj = new UnCheckedExceptionOrRunTime(); obj.print(); } }
Right click on the src folder > new > Class
Type the class package name: com.exceptions.tutorialbyexample
Type the Class name: UnCheckedExceptionOrRunTimeWithTryCatchAndFinally.java
package com.exceptions.tutorialbyexample; public class UnCheckedExceptionOrRunTimeWithTryCatchAndFinally { public UnCheckedExceptionOrRunTimeWithTryCatchAndFinally() { // TODO Auto-generated constructor stub } public void print() { int a = 10, b = 0, c; try { c = a / b; System.out.println("Value of c = " + c); } catch (java.lang.ArithmeticException e) { e.printStackTrace(); } catch (Exception e) { e.printStackTrace(); } finally { System.out.println("Inside finally"); } } public void printExit() { int a = 10, b = 0, c; try { // return ""; // System.exit(0); c = a / b; System.out.println("Value of c = " + c); } catch (java.lang.ArithmeticException e) { e.printStackTrace(); } catch (Exception e) { e.printStackTrace(); } finally { System.out.println("Inside printExit finally"); } // return null; } public static void main(String[] args) { // Creating the object of ExceptionsInJavaProgramming UnCheckedExceptionOrRunTimeWithTryCatchAndFinally obj = new UnCheckedExceptionOrRunTimeWithTryCatchAndFinally(); obj.print(); obj.printExit(); } }
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Reference form:
Oracle.com and Sun java
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