JAVA EE: June 2016

Java Tutorial : Java Exception handling (chained Exceptions)

Click here to watch in Youtube :
https://www.youtube.com/watch?v=O16v69dCUj8&list=UUhwKlOVR041tngjerWxVccw

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Java Tutorial : Java Exception handling (chained Exceptions)

MyException.java

public class MyException extends Exception
{

    public MyException(String message)
    {
        super(message);
    }
    
    public MyException(Throwable throwable)
    {
        super(throwable);
    }

    public MyException(String message, Throwable throwable)
    {
        super(message, throwable);
    }

}

ChainedExceptionDemo1.java

public class ChainedExceptionDemo1
{

    public static void main(String[] args)
    {
        try
        {
            getValue();
        }
        catch (MyException myException)
        {
            System.out.println("Cause = " + myException.getCause());
            System.out.println("Message = "
                    + myException.getMessage());
        }
    }

    public static int getValue() throws MyException
    {
        int a = 0;
        try
        {
            a = 10 / 0;
        }
        catch (ArithmeticException arithmeticException)
        {
            MyException myException = new MyException(
                    arithmeticException.getMessage(),
                    arithmeticException);
            
            throw myException;
        }

        return a;
    }

}

Output

Cause = java.lang.ArithmeticException: / by zero
Message = / by zero

ChainedExceptionDemo2.java

public class ChainedExceptionDemo2
{

    public static void main(String[] args)
    {
        try
        {
            getValue();
        }
        catch (MyException myException)
        {
            System.out.println("Cause = " + myException.getCause());
            System.out.println("Message = "
                    + myException.getMessage());
        }
    }

    public static int getValue() throws MyException
    {
        int a = 0;
        try
        {
            a = 10 / 0;
        }
        catch (ArithmeticException arithmeticException)
        {
            MyException myException = new MyException(
                    arithmeticException.getMessage());
            
            myException.initCause(arithmeticException);
            
            throw myException;
        }

        return a;
    }

}

Output

Cause = java.lang.ArithmeticException: / by zero
Message = / by zero

ChainedExceptionDemo3.java

public class ChainedExceptionDemo3
{

    public static void main(String[] args)
    {
        try
        {
            getValue();
        }
        catch (MyException myException)
        {
            System.out.println("Cause = " + myException.getCause());
            System.out.println("Message = "
                    + myException.getMessage());
        }
    }

    public static int getValue() throws MyException
    {
        int a = 0;
        try
        {
            a = 10 / 0;
        }
        catch (ArithmeticException arithmeticException)
        {
            MyException myException = new MyException(
                    arithmeticException);

            throw myException;
        }

        return a;
    }

}

Output

Cause = java.lang.ArithmeticException: / by zero
Message = java.lang.ArithmeticException: / by zero

Click the below link to download the code:
https://sites.google.com/site/javaee4321/java/ExceptionDemo_chained_exceptions_App.zip?attredirects=0&d=1

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

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/4babce59a384cb4ab41f12b03cd7d11227a4b186/BasicJava/ExceptionDemo_chained_exceptions_App/?at=master

See also:

Java Tutorial : Java Exception handling (throw Exception)

Click here to watch in Youtube :
https://www.youtube.com/watch?v=_s21JjHXsXY&list=UUhwKlOVR041tngjerWxVccw

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Java Tutorial : Java Exception handling (throw Exception)

ThrowDemo.java

public class ThrowDemo
{

    public static void main(String[] args)
    {
        getNumber("aaa");
    }

    public static int getNumber(String value)
    {
        if (!value.matches("[0-9]+"))
        {
            throw new ArithmeticException();
        }
        return Integer.parseInt(value);
    }

}

Output

Exception in thread "main" java.lang.ArithmeticException
    at ThrowDemo.getNumber(ThrowDemo.java:13)
    at ThrowDemo.main(ThrowDemo.java:6)

Click the below link to download the code:
https://sites.google.com/site/javaee4321/java/ExceptionDemo_throw_exception_App.zip?attredirects=0&d=1

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

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/4babce59a384cb4ab41f12b03cd7d11227a4b186/BasicJava/ExceptionDemo_throw_exception_App/?at=master

See also:

Java Tutorial : Java Exception handling (Specifying the exceptions thrown by a method)

Click here to watch in Youtube :
https://www.youtube.com/watch?v=SU2g7h4hN3c&list=UUhwKlOVR041tngjerWxVccw

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Java Tutorial : Java Exception handling (Specifying the exceptions thrown by a method)

ThorwsDemo.java

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;

public class ThorwsDemo
{

    public static void main(String[] args)
    {
        ThorwsDemo throwsDemo = new ThorwsDemo();

        try
        {
            String firstLine = throwsDemo
                    .readFirstLineFromFile("myfile.txt");
            System.out.println("firstLine = " + firstLine);
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }

    }

    public String readFirstLineFromFile(String path)
            throws IOException

    {
        BufferedReader br = new BufferedReader(new FileReader(path));
        String line = br.readLine();
        br.close();
        return line;
    }

}

Output

java.io.FileNotFoundException: myfile.txt (The system cannot find the file specified)
    at java.io.FileInputStream.open0(Native Method)
    at java.io.FileInputStream.open(FileInputStream.java:195)
    at java.io.FileInputStream.<init>(FileInputStream.java:138)
    at java.io.FileInputStream.<init>(FileInputStream.java:93)
    at java.io.FileReader.<init>(FileReader.java:58)
    at ThorwsDemo.readFirstLineFromFile(ThorwsDemo.java:29)
    at ThorwsDemo.main(ThorwsDemo.java:15)

Click the below link to download the code:
https://sites.google.com/site/javaee4321/java/ExceptionDemo_Specify_Exceptions_Thrown_App.zip?attredirects=0&d=1

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

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/4babce59a384cb4ab41f12b03cd7d11227a4b186/BasicJava/ExceptionDemo_Specify_Exceptions_Thrown_App/?at=master

See also:

Java Tutorial : Java Exception handling (The Try with resources statement with catch and finally)

Click here to watch in Youtube :
https://www.youtube.com/watch?v=a15n9h3UvTI&list=UUhwKlOVR041tngjerWxVccw

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Java Tutorial : Java Exception handling (The Try with resources statement with catch and finally)

TryWithResourcesDemo.java

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;

public class TryWithResourcesDemo
{

    public static void main(String[] args)
    {
        TryWithResourcesDemo tryWithResourcesDemo = new TryWithResourcesDemo();
        String firstLine = tryWithResourcesDemo
                .readFirstLineFromFile("myfile.txt");
        System.out.println("firstLine = " + firstLine);

    }

    public String readFirstLineFromFile(String path)
    {
        try (BufferedReader br = new BufferedReader(new FileReader(
                path)))
        {
            return br.readLine();
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
        finally
        {
            System.out.println("finally block is called");
        }
        return null;
    }

}

Output

finally block is called
firstLine = Peter

Click the below link to download the code:
https://sites.google.com/site/javaee4321/java/ExceptionDemo_try_with_resources_catch_finally_App.zip?attredirects=0&d=1

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

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/4babce59a384cb4ab41f12b03cd7d11227a4b186/BasicJava/ExceptionDemo_try_with_resources_catch_finally_App/?at=master

See also:

Java Tutorial : Java Exception handling (The Try with resources statement-two resources)

Click here to watch in Youtube :
https://www.youtube.com/watch?v=EXyRvT-jc9U&list=UUhwKlOVR041tngjerWxVccw

Click the below Image to Enlarge

Java Tutorial : Java Exception handling (The Try with resources statement-two resources)

TryWithResourcesDemo.java

public class TryWithResourcesDemo
{

    public static void main(String[] args) throws Exception
    {
        TryWithResourcesDemo tryWithResourcesDemo = new TryWithResourcesDemo();
        tryWithResourcesDemo.writeToFileZipFileContents("files.zip",
                "myfile.txt");
        System.out
                .println("Open zip file and create output file is done.");

    }

    /*
     * Retrieves the names of the files packaged in the zip
     * file zipFileName and creates a text file that
     * contains the names of these files.
     */

    public void writeToFileZipFileContents(String zipFileName,
            String outputFileName) throws java.io.IOException
    {

        java.nio.charset.Charset charset = java.nio.charset.StandardCharsets.US_ASCII;
        java.nio.file.Path outputFilePath = java.nio.file.Paths
                .get(outputFileName);

        // Open zip file and create output file with
        // try-with-resources statement

        try (java.util.zip.ZipFile zipFile = new java.util.zip.ZipFile(
                zipFileName);
                java.io.BufferedWriter bufferedWriter = java.nio.file.Files
                        .newBufferedWriter(outputFilePath, charset))
        {

            // Enumerate each entry
            for (java.util.Enumeration entries = zipFile.entries(); entries
                    .hasMoreElements();)
            {
                // Get the entry name and write it to the
                // output file
                String newLine = System.getProperty("line.separator");
                String zipEntryName = ((java.util.zip.ZipEntry) entries
                        .nextElement()).getName() + newLine;
                bufferedWriter.write(zipEntryName, 0,
                        zipEntryName.length());
            }
        }
    }
}

Output

Open zip file and create output file is done.

Click the below link to download the code:
https://sites.google.com/site/javaee4321/java/ExceptionDemo_the_try_with_resources_two_zip_writter_App.zip?attredirects=0&d=1

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

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/4babce59a384cb4ab41f12b03cd7d11227a4b186/BasicJava/ExceptionDemo_the_try_with_resources_two_zip_writter_App/?at=master

See also:

Java Tutorial : Java Exception handling (The Try with resources statement)

Click here to watch in Youtube :
https://www.youtube.com/watch?v=NmAH9C2O9gg&list=UUhwKlOVR041tngjerWxVccw

Click the below Image to Enlarge

Java Tutorial : Java Exception handling (The Try with resources statement)

TryWithResourcesDemo.java

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;

public class TryWithResourcesDemo
{

    public static void main(String[] args) throws Exception
    {
        TryWithResourcesDemo tryWithResourcesDemo = new TryWithResourcesDemo();
        String firstLine = tryWithResourcesDemo.readFirstLineFromFile("myfile.txt");
        System.out.println("firstLine = "+firstLine);
            
    }

    public String readFirstLineFromFile(String path)
            throws IOException
    {
        try (BufferedReader br = new BufferedReader(new FileReader(
                path)))
        {
            return br.readLine();
        }
    }

}

Output

firstLine = Peter

FinallyDemo.java

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;

public class FinallyDemo
{

    public static void main(String[] args) throws IOException
    {
        FinallyDemo finallyDemo = new FinallyDemo();
        String firstLine = finallyDemo.readFirstLineFromFile("myfile.txt");
        System.out.println("firstLine = "+firstLine);

    }
    
    public String readFirstLineFromFile(String path)
            throws IOException
    {
        BufferedReader br = new BufferedReader(new FileReader(path));
        try
        {
            return br.readLine();
        }
        finally
        {
             if (br != null)
             {
                 br.close();
             }
        }
    }
}

Output

firstLine = Peter

Click the below link to download the code:
https://sites.google.com/site/javaee4321/java/ExceptionDemo_The_try_with_Resources_statement_App.zip?attredirects=0&d=1

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

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/4babce59a384cb4ab41f12b03cd7d11227a4b186/BasicJava/ExceptionDemo_The_try_with_Resources_statement_App/?at=master

See also:

Java Tutorial : Java Exception handling (Try with resources-custom AutoClosable implementation)

Click here to watch in Youtube :
https://www.youtube.com/watch?v=TQba1G_Pkr4&list=UUhwKlOVR041tngjerWxVccw

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Java Tutorial : Java Exception handling (Try with resources-custom AutoClosable implementation)

MyBufferedReader.java

public class MyBufferedReader implements AutoCloseable
{

    public void read()
    {
        System.out.println("read method is called...");
    }

    @Override
    public void close() throws Exception
    {
        System.out.println("close method is called...");
    }

}


TryWithResourcesDemo.java
public class TryWithResourcesDemo
{

    public static void main(String[] args) throws Exception
    {
        try (MyBufferedReader myBufferedReader = new MyBufferedReader())
        {
            myBufferedReader.read();
        }
    }

}

Output

read method is called...
close method is called...

Click the below link to download the code:
https://sites.google.com/site/javaee4321/java/ExceptionDemo_Custom_AutoClosable_impl_App.zip?attredirects=0&d=1

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

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/4babce59a384cb4ab41f12b03cd7d11227a4b186/BasicJava/ExceptionDemo_Custom_AutoClosable_impl_App/?at=master

See also:

Java Tutorial : Java Exception handling (Try with resources in Java) - Playlist

Click here to watch in Youtube :
https://www.youtube.com/watch?v=95Cr46hO52M&list=PLmCsXDGbJHdjfNuRg6ezzXLxpkM-z2ask

See also:

Java Tutorial : Java Exception handling (Try with resources using multiple resources)

Click here to watch in Youtube :
https://www.youtube.com/watch?v=hAZkzOwpShE&list=UUhwKlOVR041tngjerWxVccw

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Java Tutorial : Java Exception handling (Try with resources using multiple resources)

TryWithResourcesDemo.java

import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.io.IOException;

public class TryWithResourcesDemo
{

    public static void main(String[] args) throws IOException
    {
        try (FileInputStream fileInputStream = new FileInputStream(
                "myfile.txt");
                BufferedInputStream bufferedInputStream = new BufferedInputStream(
                        fileInputStream))
        {
            int data = bufferedInputStream.read();
            while (data != -1)
            {
                System.out.print((char) data);
                data = bufferedInputStream.read();
            }
        }

    }

}

Output

Peter
David
Julia

Click the below link to download the code:
https://sites.google.com/site/javaee4321/java/ExceptionDemo_try_with_resources_multi_App.zip?attredirects=0&d=1

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

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/4babce59a384cb4ab41f12b03cd7d11227a4b186/BasicJava/ExceptionDemo_try_with_resources_multi_App/?at=master

See also:

Java Tutorial : Java Exception handling (Try with resources)

Click here to watch in Youtube :
https://www.youtube.com/watch?v=95Cr46hO52M&list=UUhwKlOVR041tngjerWxVccw

Click the below Image to Enlarge

Java Tutorial : Java Exception handling (Try with resources)

ExceptionHandlingDemo.java

import java.io.FileInputStream;
import java.io.IOException;

public class ExceptionHandlingDemo
{

    public static void main(String[] args)
    {
        FileInputStream fileInputStream = null;
        try
        {
            fileInputStream = new FileInputStream("myfile.txt");
            int data = fileInputStream.read();
            while (data != -1)
            {
                System.out.print((char) data);
                data = fileInputStream.read();
            }
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
        finally
        {
            if (fileInputStream != null)
            {
                try
                {
                    fileInputStream.close();
                }
                catch (IOException e)
                {
                    e.printStackTrace();
                }
            }
        }

    }
}

Output
Hi

TryWithResourcesDemo.java

import java.io.FileInputStream;
import java.io.IOException;

public class TryWithResourcesDemo
{

    public static void main(String[] args) throws IOException
    {
        try (FileInputStream fileInputStream = new FileInputStream("myfile.txt"))
        {
            int data = fileInputStream.read();
            while (data != -1)
            {
                System.out.print((char) data);
                data = fileInputStream.read();
            }
        }

    }

}

Output

Hi

Refer:
https://docs.oracle.com/javase/8/docs/api/index.html?java/lang/AutoCloseable.html

Click the below link to download the code:
https://sites.google.com/site/javaee4321/java/ExceptionDemo_try_with_resources_App.zip?attredirects=0&d=1

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

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/4babce59a384cb4ab41f12b03cd7d11227a4b186/BasicJava/ExceptionDemo_try_with_resources_App/?at=master

See also:

Java Tutorial : Java Exception handling (The finally block)

Click here to watch in Youtube :
https://www.youtube.com/watch?v=JS6fT6QOZUU&list=UUhwKlOVR041tngjerWxVccw

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Java Tutorial : Java Exception handling (The finally block)

FinallyBlockDemo.java

public class FinallyBlockDemo
{

    public static void main(String[] args)
    {

        try
        {
            String str = null;

            // This line will throw NullPointerException
            System.out.println(str.length());

            // This line will throw ArithmeticException
            int a = 5 / 0;

        }

        catch (ArithmeticException | NullPointerException exe)
        {
            exe.printStackTrace();
        }
        finally
        {
            System.out.println("finally block is called.");
            //clean up code.
        }

    }
}

Output

java.lang.NullPointerException
    at FinallyBlockDemo.main(FinallyBlockDemo.java:12)
finally block is called.

Click the below link to download the code:
https://sites.google.com/site/javaee4321/java/ExceptionDemo_The_finally_Block_App.zip?attredirects=0&d=1

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

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/4babce59a384cb4ab41f12b03cd7d11227a4b186/BasicJava/ExceptionDemo_The_finally_Block_App/?at=master

See also: