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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