Friday, 17 June 2016

Java Tutorial : Java unchecked exception(NullPointerException and NumberFormatException)


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Java Tutorial : Java unchecked exception(NullPointerException and NumberFormatException)
UnCheckedExceptionDemo1.java
/*
 * If you compile this code, it would compile
 * successfully however when you will run it, it would
 * throw NullPointerException. That clearly shows that
 * unchecked exceptions are not checked at compile-time,
 * they are being checked at runtime.
 */

public class UnCheckedExceptionDemo1
{
    public static void main(String[] args)
    {
        String str = null;
        /*
         * str is null, so it should throw
         * NullPointerException
         */
        System.out.println(str.isEmpty());
        System.out.println("Normal flow...");
    }

}
Output
Exception in thread "main" java.lang.NullPointerException
    at UnCheckedExceptionDemo1.main(UnCheckedExceptionDemo1.java:18)
UnCheckedExceptionDemo2.java
/*
 * If you compile this code, it would compile
 * successfully however when you will run it, it would
 * throw NumberFormatException. That clearly shows that
 * unchecked exceptions are not checked at compile-time,
 * they are being checked at runtime.
 */

public class UnCheckedExceptionDemo2
{
    public static void main(String[] args)
    {
        String str = "abc";
        /*
         * str is "abc", so it should throw
         * NumberFormatException
         */
        int i=Integer.parseInt(str);
        System.out.println(i);
        System.out.println("Normal flow...");
    }

}
Output
Exception in thread "main" java.lang.NumberFormatException: For input string: "abc"
    at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
    at java.lang.Integer.parseInt(Integer.java:580)
    at java.lang.Integer.parseInt(Integer.java:615)
    at UnCheckedExceptionDemo2.main(UnCheckedExceptionDemo2.java:18)
Click the below link to download the code:
https://sites.google.com/site/javaee4321/java/ExceptionDemo_UncheckedException_NPE_NFE_App.zip?attredirects=0&d=1

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

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/2edf29d684ae5278e3d99171112d04090b378c86/BasicJava/ExceptionDemo_UncheckedException_NPE_NFE_App/?at=master

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