NullPointerException
KW.java
class KW
{
    public static void main(String args[])
    {
        String s=null;
        System.out.println("Length: "+s.length());
    }
}
Output
kodingwindow@kw:~$ javac KW.java
kodingwindow@kw:~$ java KW
Exception in thread "main" java.lang.NullPointerException
    at KW.main(KW.java:6)
kodingwindow@kw:~$
Java program to demonstrate the use of try and catch blocks
KW.java
class KW
{
    public static void main(String args[])
    {
        String s=null;
        try
        {
            System.out.println("Length: "+s.length());
        }
        catch(Exception e)
        {
            System.out.println("String is null, hence, Unable to find the length.");
        }
    }
}
Output
kodingwindow@kw:~$ javac KW.java
kodingwindow@kw:~$ java KW
String is null, hence, Unable to find the length.
kodingwindow@kw:~$
Java program to demonstrate the use of try with multiple catch blocks
KW.java
class KW
{
    public static void main(String args[])
    {
        String s=null;
        try
        {
            System.out.println("Length: "+s.length());
        }
        catch(ArithmeticException e)
        {
            System.out.println("Exception caught in the first catch block");
        }
        catch(NullPointerException e)
        {
            System.out.println("Exception caught in the second catch block");
        }
        catch(Exception e)
        {
            System.out.println("Exception caught in the third catch block");
        }
    }
}
Output
kodingwindow@kw:~$ javac KW.java
kodingwindow@kw:~$ java KW
Exception caught in the second catch block
kodingwindow@kw:~$
Java program to handle the NullPointerException using Exception class
KW.java
class KW
{
    public static void main(String args[])
    {
        String s=null;
        try
        {
            System.out.println("Length: "+s.length());
        }
        catch(ArithmeticException e)
        {
            System.out.println("Exception caught in the first catch block");
        }
        catch(StringIndexOutOfBoundsException e)
        {
            System.out.println("Exception caught in the second catch block");
        }
        catch(Exception e)
        {
            System.out.println("Exception caught in the third catch block");
        }
    }
}
Output
kodingwindow@kw:~$ javac KW.java
kodingwindow@kw:~$ java KW
Exception caught in the third catch block
kodingwindow@kw:~$
Java program to handle the NullPointerException using RuntimeException class
KW.java
class KW
{
    public static void main(String args[])
    {
        String s=null;
        try
        {
            System.out.println("Length: "+s.length());
        }
        catch(ArithmeticException e)
        {
            System.out.println("Exception caught in the first catch block");
        }
        catch(RuntimeException e)
        {
            System.out.println("Exception caught in the second catch block");
        }
        catch(Exception e)
        {
            System.out.println("Exception caught in the third catch block");
        }
    }
}
Output
kodingwindow@kw:~$ javac KW.java
kodingwindow@kw:~$ java KW
Exception caught in the second catch block
kodingwindow@kw:~$
The following sequence of multiple catch blocks are not allowed
KW.java
class KW
{
    public static void main(String args[])
    {
        String s=null;
        try
        {
            System.out.println("Length: "+s.length());
        }
        catch(Exception e)
        {
            System.out.println("Exception caught in the third catch block");
        }
        catch(RuntimeException e)
        {
            System.out.println("Exception caught in the second catch block");
        }
        catch(ArithmeticException e)
        {
            System.out.println("Exception caught in the first catch block");
        }
    }
}
Output
kodingwindow@kw:~$ javac KW.java
kodingwindow@kw:~$ java KW
KW.java:14: error: exception RuntimeException has already been caught
        catch(RuntimeException e)
        ^
KW.java:18: error: exception ArithmeticException has already been caught
        catch(ArithmeticException e)
        ^
2 errors
kodingwindow@kw:~$
What Next?
Java program to demonstrate the use of finally block Java program to demonstrate the use of nested try, catch, and finally blocks Java program to handle the ArithmeticException
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