JAVA EE: May 2016

Java Tutorial : Java checked exception and unchecked exception(Version2)

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Java Tutorial : Java checked exception and unchecked exception(Version2)

See also:

Java checked exception and unchecked exception - Playlist

Click here to watch in Youtube :
https://www.youtube.com/watch?v=Wwc6FxlxFHQ&list=PLmCsXDGbJHdivFI5Whei0t6dwfojYqFVA

See also:

Java Tutorial : Java checked exception and unchecked exception(Version1)

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https://www.youtube.com/watch?v=Wwc6FxlxFHQ&list=UUhwKlOVR041tngjerWxVccw

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Java Tutorial : Java checked exception and unchecked exception(Version1)

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Java Tutorial : Java Exception class hierarchy - Playlist

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https://www.youtube.com/watch?v=_GkSmiVjzC8&list=PLmCsXDGbJHdj7DIZ4mibXPAJciIni5Opl
See also:

Java Tutorial : Java Exception class hierarchy(Version3)

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https://www.youtube.com/watch?v=gRjHkq8n8xI&list=UUhwKlOVR041tngjerWxVccw

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Java Tutorial : Java Exception class hierarchy(Version3)

See also:

Java Tutorial : Java Exception class hierarchy(Version2)

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https://www.youtube.com/watch?v=SxBBtaHKrTs&list=UUhwKlOVR041tngjerWxVccw

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Java Tutorial : Java Exception class hierarchy(Version2)

See also:

Java Tutorial : Java Exception class hierarchy(Version1)

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Java Tutorial : Java Exception class hierarchy(Version1)

Refer:

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

See also:

Java Tutorial : Java Exception Handling

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https://www.youtube.com/watch?v=3WfBUqHxqKE&list=UUhwKlOVR041tngjerWxVccw

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Java Tutorial : Java Exception Handling

ExceptionHandlingDemo1.java

/*
 * With out exception handling
 */
public class ExceptionHandlingDemo1
{

    public static void main(String[] args)
    {
        int intValue = 50;
        System.out.println("intValue = " + intValue);

        double doubleValue = 45.9;
        System.out.println("doubleValue = " + doubleValue);

        String str = null;
        System.out.println("str = " + str.toString());

        float floatValue = 10.f;
        System.out.println("floatValue = " + floatValue);

        long longValue = 45000;
        System.out.println("longValue = " + longValue);

    }

}

Output

intValue = 50
doubleValue = 45.9
Exception in thread "main" java.lang.NullPointerException
    at ExceptionHandlingDemo1.main(ExceptionHandlingDemo1.java:16)

ExceptionHandlingDemo2.java

/*
 * With exception handling.
 */
public class ExceptionHandlingDemo2
{

    public static void main(String[] args)
    {
        int intValue = 50;
        System.out.println("intValue = " + intValue);

        double doubleValue = 45.9;
        System.out.println("doubleValue = " + doubleValue);

        try
        {
            String str = null;
            System.out.println("str = " + str.toString());
        }
        catch(Exception exe)
        {
             System.out.println("String value is null");
        }
        

        float floatValue = 10.f;
        System.out.println("floatValue = " + floatValue);

        long longValue = 45000;
        System.out.println("longValue = " + longValue);

    }

}

Output

intValue = 50
doubleValue = 45.9
String value is null
floatValue = 10.0
longValue = 45000

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

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

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/c539eeaf4c6ff331d8e2aa2333826ea70c999093/BasicJava/ExceptionDemo_Exception_handling_App/?at=master

See also:

Java Tutorial : Java exception handling - Playlist

Click here to watch in Youtube :
https://www.youtube.com/watch?v=CVX9ktKWfCw&list=PLmCsXDGbJHdibElN6tZVVYiNfsbiFTYXr

See also:

Java Tutorial : Java what is an Exception

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https://www.youtube.com/watch?v=CVX9ktKWfCw&list=UUhwKlOVR041tngjerWxVccw

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Java Tutorial : Java what is an Exception

ExceptionDemo.java

public class ExceptionDemo
{

    public static void main(String[] args)
    {
        int intValue = 50;
        System.out.println("intValue = " + intValue);

        double doubleValue = 45.9;
        System.out.println("doubleValue = " + doubleValue);

        String str = null;
        System.out.println("str = " + str.toString());

        float floatValue = 10.f;
        System.out.println("floatValue = " + floatValue);

        long longValue = 45000;
        System.out.println("longValue = " + longValue);

    }

}

Output

intValue = 50
doubleValue = 45.9
Exception in thread "main" java.lang.NullPointerException
    at ExceptionDemo.main(ExceptionDemo.java:14)

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

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

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/c539eeaf4c6ff331d8e2aa2333826ea70c999093/BasicJava/ExceptionDemo_What_is_an_Exception_App/?at=master

See also:

Java Tutorial : Java Autoboxing and Unboxing - Playlist

Click here to watch in Youtube :
https://www.youtube.com/watch?v=0zQHpWf2mJg&list=PLmCsXDGbJHdgCk0ZHLI_TgdDzmlKndNvy

See also:

Java Tutorial : Java Unboxing

Click here to watch in Youtube :
https://www.youtube.com/watch?v=zqjl1ElyC2c&list=UUhwKlOVR041tngjerWxVccw

UnBoxingDemo.java

import java.util.ArrayList;
import java.util.List;

public class UnBoxingDemo
{

    public static void main(String[] args)
    {
        Integer integerObj = new Integer(-8);

        // 1. Unboxing through method invocation
        int absVal = absoluteValue(integerObj);
        System.out.println("absolute value of " + integerObj + " = " + absVal);

        List<Double> list = new ArrayList<>();
        list.add(new Double(12.3)); 

        // 2. Unboxing through assignment
        double doubleValue = list.get(0);
        System.out.println("doubleValue = " + doubleValue);

    }

    public static int absoluteValue(int i)
    {
        return (i < 0) ? -i : i;
    }

}

Output

absolute value of -8 = 8
doubleValue = 12.3

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

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

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/c539eeaf4c6ff331d8e2aa2333826ea70c999093/BasicJava/UnBoxingDemo_App/?at=master

See also:

Wednesday, 11 May 2016

Java Tutorial : Java Unboxing (list)

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https://www.youtube.com/watch?v=9kqevy2o6FA&list=UUhwKlOVR041tngjerWxVccw

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Java Tutorial : Java Unboxing (list)

UnBoxingDemo.java

import java.util.ArrayList;
import java.util.List;

public class UnBoxingDemo
{

    public static void main(String[] args)
    {
        List<Integer> list = new ArrayList<>();
        list.add(new Integer(1));
        list.add(new Integer(2));
        for (Integer integerObj : list)
        {
            int i = integerObj; // Unboxing
            System.out.println(i);
        }

    }

}

Output

1
2

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

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

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/c539eeaf4c6ff331d8e2aa2333826ea70c999093/BasicJava/UnBoxingDemo_list_App/?at=master

See also:

Java Tutorial : Java Autoboxing (list)

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https://www.youtube.com/watch?v=5sN2E4cJJ7w&list=UUhwKlOVR041tngjerWxVccw

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Java Tutorial : Java Autoboxing (list)

AutoBoxingDemo.java

import java.util.ArrayList;
import java.util.List;

public class AutoBoxingDemo
{

    public static void main(String[] args)
    {
        List<Integer> li = new ArrayList<>();

        for (int i = 1; i < 20; i += 2)
        {
            li.add(i);
        }
        System.out.println(li);
        System.out.println(li.get(0).getClass());
    }

}

Output

[1, 3, 5, 7, 9, 11, 13, 15, 17, 19]
class java.lang.Integer

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

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

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/c539eeaf4c6ff331d8e2aa2333826ea70c999093/BasicJava/AutoBoxing_Demo_List_App/?at=master

See also:

Java Tutorial : Java Autoboxing and Unboxing

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https://www.youtube.com/watch?v=0zQHpWf2mJg&list=UUhwKlOVR041tngjerWxVccw

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Java Tutorial : Java Autoboxing and Unboxing

AutoBoxingDemo.java

public class AutoBoxingDemo
{

    public static void main(String[] args)
    {
        int intValue = 50;
        Integer integerObj = intValue;// Boxing
        System.out.println(integerObj);
        
        display(intValue); //Boxing
    }
    
    public static void display(Integer integerObj)
    {
        System.out.println(integerObj);
    }

}
Output

50
50

UnboxingDemo.java

public class UnboxingDemo
{
    public static void main(String[] args)
    {
        Integer integerObj = new Integer(100);
        int intValue = integerObj; // UnBoxing
        System.out.println(intValue);
        
        display(integerObj);//UnBoxing
    }

    public static void display(int intValue)
    {
        System.out.println(intValue);
    }
}

Output

100
100

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

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

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/c539eeaf4c6ff331d8e2aa2333826ea70c999093/BasicJava/AutoBoxing_UnBoxingDemo_App/?at=master

See also:

Java Tutorial : Java StringBuilder [supported methods]

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https://www.youtube.com/watch?v=FvN0Qi6gFQ0&list=UUhwKlOVR041tngjerWxVccw

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Java Tutorial : Java StringBuilder [supported methods]

See also:

Java Tutorial : Java StringBuilder [length and Capacity]

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https://www.youtube.com/watch?v=ZJcGw4LrF1s&list=UUhwKlOVR041tngjerWxVccw

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Java Tutorial : Java StringBuilder [length and Capacity]

See also:

Java Tutorial : Java String vs StringBuffer vs StringBuilder(memory test)

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

StringMemoryTest.java

public class StringMemoryTest
{

    private static final int KBinBytes = 1024;

    /**
     * Perform GC
     */
    private void performGC()
    {
        for (int i = 0; i < 10; i++)
        {
            System.gc();
            try
            {
                Thread.sleep(100);
            }
            catch (InterruptedException e)
            {
                Thread.currentThread().interrupt();
            }
        }
    }

    /**
     * Get the memory used value.
     * 
     * @return long
     */
    private long memoryUsed()
    {
        return ((Runtime.getRuntime().totalMemory() / KBinBytes) - (Runtime
                .getRuntime().freeMemory() / KBinBytes));
    }

    /**
     * Method to test String object memory consumption in a
     * BIG loop
     */
    public void testStringMemory()
    {
        System.out
                .println("Initial Total memory in Java virtual machine in KBs="
                        + Runtime.getRuntime().totalMemory()
                        / KBinBytes);
        System.out
                .println("Initial Free memory in Java virtual machine in KBs="
                        + Runtime.getRuntime().freeMemory()
                        / KBinBytes);
        long initialmemory = memoryUsed();
        long startTime = System.currentTimeMillis();
        String str = "";
        for (int i = 1; i < 50000; i++)
        {
            str = str + "Hello";
        }
        long stopTime = System.currentTimeMillis();
        long elapsedTime = stopTime - startTime;
        System.out.println("Time taken to complete the process in MilliSeconds:"
                + elapsedTime);

        System.out.println("Memory used by String in KBs="
                + (memoryUsed() - initialmemory));
        str = null;
        performGC();
        System.out.println("Free Memory after GC in KBs="
                + Runtime.getRuntime().freeMemory() / KBinBytes);

    }

    /**
     * Method to test StringBuilder object memory
     * consumption in a BIG loop
     */
    public void testStringBuilderMemory()
    {
        System.out
                .println("Initial Total memory in Java virtual machine in KBs="
                        + Runtime.getRuntime().totalMemory()
                        / KBinBytes);
        System.out
                .println("Initial Free memory in Java virtual machine in KBs="
                        + Runtime.getRuntime().freeMemory()
                        / KBinBytes);
        long initialmemory = memoryUsed();
        long startTime = System.currentTimeMillis();
        StringBuilder sb = new StringBuilder();
        for (int i = 1; i < 50000; i++)
        {
            sb.append("Hello");
        }
        long stopTime = System.currentTimeMillis();
        long elapsedTime = stopTime - startTime;
        System.out
                .println("Time taken to complete the process in MilliSeconds:"
                        + elapsedTime);
        System.out.println("Memory used by StringBuilder in KBs="
                + (memoryUsed() - initialmemory));
        sb = null;
        performGC();
        System.out.println("Free Memory after GC in KBs="
                + Runtime.getRuntime().freeMemory() / KBinBytes);

    }

    /**
     * Method to test StringBuffer object memory consumption
     * in a BIG loop
     */
    public void testStringBufferMemory()
    {
        System.out
                .println("Initial Total memory in Java virtual machine in KBs="
                        + Runtime.getRuntime().totalMemory()
                        / KBinBytes);
        System.out
                .println("Initial Free memory in Java virtual machine in KBs="
                        + Runtime.getRuntime().freeMemory()
                        / KBinBytes);
        long initialmemory = memoryUsed();
        long startTime = System.currentTimeMillis();
        StringBuffer sb = new StringBuffer();

        for (int i = 1; i < 50000; i++)
        {
            sb.append("Hello");
        }
        long stopTime = System.currentTimeMillis();
        long elapsedTime = stopTime - startTime;
        System.out.println("Time taken to complete the process in MilliSeconds:"
                + elapsedTime);
        System.out.println("Memory used by StringBuffer in KBs="
                + (memoryUsed() - initialmemory));
        sb = null;
        performGC();
        System.out.println("Free Memory after GC in KBs="
                + Runtime.getRuntime().freeMemory() / KBinBytes);

    }

    /**
     * Main class
     * 
     * @param args
     */
    public static void main(String[] args)
    {
        System.out
                .println("Initial Max memory in Java virtual machine in KBs="
                        + Runtime.getRuntime().maxMemory()
                        / KBinBytes);
        StringMemoryTest memoryTest = new StringMemoryTest();
        System.out.println(".....................................................\nString memory test\n");
        memoryTest.testStringMemory();
        System.out.println(".................................................\nStringBuffer memory test\n");
        memoryTest.testStringBufferMemory();
        System.out.println("...............................................\nStringBuilder memory test\n");
        memoryTest.testStringBuilderMemory();

    }

}

Output

Initial Max memory in Java virtual machine in KBs=919552
...........................................................
String memory test

Initial Total memory in Java virtual machine in KBs=62976
Initial Free memory in Java virtual machine in KBs=61992
Time taken to complete the process in MilliSeconds:7729
Memory used by String in KBs=130666
Free Memory after GC in KBs=349431
...........................................................
StringBuffer memory test

Initial Total memory in Java virtual machine in KBs=355840
Initial Free memory in Java virtual machine in KBs=349431
Time taken to complete the process in MilliSeconds:11
Memory used by StringBuffer in KBs=0
Free Memory after GC in KBs=348918
............................................................
StringBuilder memory test

Initial Total memory in Java virtual machine in KBs=355328
Initial Free memory in Java virtual machine in KBs=348918
Time taken to complete the process in MilliSeconds:5
Memory used by StringBuilder in KBs=0
Free Memory after GC in KBs=348406

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

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

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/c539eeaf4c6ff331d8e2aa2333826ea70c999093/BasicJava/StringBuilderDemo_MemoryTest_App/?at=master

See also: