Tuesday, 21 June 2016

Java Tutorial : Java Exception handling (Unreachable catch block)


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Java Tutorial : Java Exception handling (Unreachable catch block) 
Java Tutorial : Java Exception handling (Unreachable catch block) 
Java Tutorial : Java Exception handling (Unreachable catch block) 
ExceptionDemo1.java
public class ExceptionDemo1
{
    public static void main(String[] args)
    {

        String firstName = null;

        try
        {
            // It will throw NullPointerException
            System.out.println(firstName.length());
        }
        catch (NullPointerException nullPointerException)
        {
            System.out.println("String value is null.");
        }
        catch (Exception exception)
        {
            exception.printStackTrace();
        }

        String lastName = "Peter";
        String fullName = firstName + lastName;
        System.out.println("fullName = " + fullName);

    }

}
Output
String value is null.
fullName = nullPeter
ExceptionDemo2.java
public class ExceptionDemo2
{
    public static void main(String[] args)
    {
        String firstName = null;

        try
        {
            // It will throw NullPointerException
            System.out.println(firstName.length());
        }
        catch (Exception exception)
        {
            exception.printStackTrace();
        }

        String lastName = "Peter";
        String fullName = firstName + lastName;
        System.out.println("fullName = " + fullName);
    }
}
Output
java.lang.NullPointerException
    at ExceptionDemo2.main(ExceptionDemo2.java:10)
fullName = nullPeter
ExceptionDemo3.java
public class ExceptionDemo3
{
    public static void main(String[] args)
    {

        String firstName = null;

        try
        {
            // It will throw NullPointerException
            System.out.println(firstName.length());
        }

        catch (Exception exception)
        {
            exception.printStackTrace();
        }

        catch (NullPointerException nullPointerException)
        {
            System.out.println("String value is null.");
        }

        String lastName = "Peter";
        String fullName = firstName + lastName;
        System.out.println("fullName = " + fullName);

    }
}
Output
Exception in thread "main" java.lang.Error: Unresolved compilation problem: 
    Unreachable catch block for NullPointerException. It is already handled by the catch block for Exception

    at ExceptionDemo3.main(ExceptionDemo3.java:19)
Click the below link to download the code:
https://sites.google.com/site/javaee4321/java/ExceptionDemo_Unreachable_catch_App.zip?attredirects=0&d=1

Github Link:
https://github.com/ramram43210/Java/tree/master/BasicJava/ExceptionDemo_Unreachable_catch_App

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/a4490537e1a166e28ac44e3caed727d335adc51d/BasicJava/ExceptionDemo_Unreachable_catch_App/?at=master

See also:
  • All JavaEE Viedos Playlist
  • All JavaEE Viedos
  • All JAVA EE Links
  • Servlets Tutorial
  • All Design Patterns Links
  • JDBC Tutorial
  • Java Collection Framework Tutorial
  • JAVA Tutorial
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