JAVA EE: November 2015

Thursday, 26 November 2015

Java Tutorial : Java pass by value (primitive data type)

Click here to watch in Youtube :
https://www.youtube.com/watch?v=AaxzVX3Zfa8&list=UUhwKlOVR041tngjerWxVccw

PassPrimitiveDatatypeTest.java

public class PassPrimitiveDatatypeTest
{

    public static void main(String[] args)
    {

        int x = 3;

        changeIt(x);

        System.out.println("x value inside main method : " + x);

    }

    /*
     * Passing Primitive Data Type Arguments :
     * 
     * Primitive arguments, such as an int or a double, are passed into methods
     * by value. This means that any changes to the values of the parameters
     * exist only within the scope of the method. When the method returns, the
     * parameters are gone and any changes to them are lost.
     */

    public static void changeIt(int x)
    {
        x = 50;
        System.out.println("x value inside changeIt method : " + x);
        return;
    }

}

Output

x value inside changeIt method : 50
x value inside main method : 3

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

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

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/2f20a20e875ab6e7de15adc0041c373263d61c3b/BasicJava/PassInfoDemoApp/?at=master

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JAVA Tutorial

Java Tutorial : Java overloaded Constructors

Click here to watch in Youtube :
https://www.youtube.com/watch?v=5Kqdc087J4o&list=UUhwKlOVR041tngjerWxVccw

Click the below Image to Enlarge

Java Tutorial : Java overloaded Constructors

Employee.java

public class Employee
{

    private String name;
    private int age;

    public Employee()
    {
        System.out.println("Inside Employee() constructor");
    }

    public Employee(String name)
    {
        System.out.println("Inside  Employee(String name) constructor");
        this.name = name;
    }

    public Employee(String name, int age)
    {
        System.out.println("Inside  Employee(String name,int age) constructor");
        this.name = name;
        this.age = age;
    }

    public Employee(int age)
    {
        System.out.println("Inside  Employee(int age) constructor");
        this.age = age;
    }

    public String getName()
    {
        return name;
    }

    public void setName(String name)
    {
        this.name = name;
    }

    public int getAge()
    {
        return age;
    }

    public void setAge(int age)
    {
        this.age = age;
    }

}

EmployeeDemoTest.java

public class EmployeeDemoTest
{

    public static void main(String[] args)
    {

        Employee employeeObject1 = new Employee();
        System.out.println("Name : " + employeeObject1.getName());
        System.out.println("Age  : " + employeeObject1.getAge());

        System.out.println("------------------------------------");

        Employee employeeObject2 = new Employee("Dave");
        System.out.println("Name : " + employeeObject2.getName());
        System.out.println("Age  : " + employeeObject2.getAge());

        System.out.println("------------------------------------");

        Employee employeeObject3 = new Employee("John", 45);
        System.out.println("Name : " + employeeObject3.getName());
        System.out.println("Age  : " + employeeObject3.getAge());
        
        System.out.println("------------------------------------");

        Employee employeeObject4 = new Employee(54);
        System.out.println("Name : " + employeeObject4.getName());
        System.out.println("Age  : " + employeeObject4.getAge());

    }

}

Output

Inside Employee() constructor
Name : null
Age  : 0
------------------------------------
Inside  Employee(String name) constructor
Name : Dave
Age  : 0
------------------------------------
Inside  Employee(String name,int age) constructor
Name : John
Age  : 45
------------------------------------
Inside  Employee(int age) constructor
Name : null
Age  : 54

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

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

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/2f20a20e875ab6e7de15adc0041c373263d61c3b/BasicJava/ConstructorDemoOverloadedApp/?at=master

See also:

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Servlets Tutorial

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JDBC Tutorial

Java Collection Framework Tutorial

JAVA Tutorial

Java Tutorial : Java private Constructor

Click here to watch in Youtube :
https://www.youtube.com/watch?v=H4wixwtXXiE&list=UUhwKlOVR041tngjerWxVccw

Employee.java

public class Employee
{

    private String name;
    private int age;

    private Employee()
    {
        System.out.println("Inside Employee() constructor");
    }

    public String getName()
    {
        return name;
    }

    public void setName(String name)
    {
        this.name = name;
    }

    public int getAge()
    {
        return age;
    }

    public void setAge(int age)
    {
        this.age = age;
    }
}

EmployeeDemoTest.java

public class EmployeeDemoTest
{

    public static void main(String[] args)
    {

        Employee employeeObject1 = new Employee();
        System.out.println("Name : " + employeeObject1.getName());
        System.out.println("Age  : " + employeeObject1.getAge());

    }

}

Output

Exception in thread "main" java.lang.Error: Unresolved compilation problem: 
    The constructor Employee() is not visible

    at EmployeeDemoTest.main(EmployeeDemoTest.java:7)

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

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

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/2f20a20e875ab6e7de15adc0041c373263d61c3b/BasicJava/ConstructorDemoPrivateApp/?at=master

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JAVA Tutorial

Wednesday, 25 November 2015

Java Tutorial : Java Constructor

Click here to watch in Youtube :
https://www.youtube.com/watch?v=qK7f-q5brOU&list=UUhwKlOVR041tngjerWxVccw

Click the below Image to Enlarge

Java Tutorial : Java Constructor

Employee.java

public class Employee
{

    private String name;
    private int age;

    public Employee(String name, int age)
    {
        this.name = name;
        this.age = age;
    }

    public String getName()
    {
        return name;
    }

    public void setName(String name)
    {
        this.name = name;
    }

    public int getAge()
    {
        return age;
    }

    public void setAge(int age)
    {
        this.age = age;
    }

}

EmployeeDemoTest.java

public class EmployeeDemoTest
{

    public static void main(String[] args)
    {
        Employee davidEmployee = new Employee("David", 25);
        System.out.println("Name : " + davidEmployee.getName());
        System.out.println("Age  : " + davidEmployee.getAge());
        System.out.println("-------------------------------");
        Employee johnEmployee = new Employee("John", 45);
        System.out.println("Name : " + johnEmployee.getName());
        System.out.println("Age  : " + johnEmployee.getAge());

    }

}

Output

Name : David
Age  : 25
-------------------------------
Name : John
Age  : 45

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

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

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/2f20a20e875ab6e7de15adc0041c373263d61c3b/BasicJava/ConstructorDemoConstructorsApp/?at=master

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JAVA Tutorial

Java Tutorial : Java default Constructor

Click here to watch in Youtube :
https://www.youtube.com/watch?v=l4MOZkuRtfo&list=UUhwKlOVR041tngjerWxVccw

Employee.java

public class Employee
{

    String name;
    int age;

    /*
     * The compiler automatically provides a no-argument default constructor if
     * the class does not have any other constructor.
     * 
     * This default constructor will call the no-argument constructor of the
     * superclass. In this situation, the compiler will complain if the
     * superclass doesn't have a no-argument constructor so you must verify that
     * it does. If your class has no explicit superclass, then it has an
     * implicit superclass of Object, which does have a no-argument constructor.
     */

}

EmployeeDemoTest.java

public class EmployeeDemoTest
{

    public static void main(String[] args)
    {
        /*
         * Invokes the no-argument constructor to create a new Employee object
         * called employee.
         */
        Employee employee = new Employee();
        System.out.println("Name : " + employee.name);
        System.out.println("Age  : " + employee.age);

    }

}

Output

Name : null
Age  : 0

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

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

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/2f20a20e875ab6e7de15adc0041c373263d61c3b/BasicJava/ConstructorDemoDefaultconstructorApp/?at=master

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JAVA Tutorial

Java Tutorial : Java Overloading methods

Click here to watch in Youtube :
https://www.youtube.com/watch?v=Qkl-vc3SbX8&list=UUhwKlOVR041tngjerWxVccw

Click the below Image to Enlarge

Java Tutorial : Java Overloading methods

DisplayValue.java

public class DisplayValue
{

    public static void main(String[] args)
    {
        DisplayValue displayValue = new DisplayValue();
        displayValue.displayValue("Hello");
        displayValue.displayValue(10);
        displayValue.displayValue(200, 400);
    }

    public void displayValue(String str)
    {
        System.out.println("displayValue(String str) has been called : " + str);
    }

    public void displayValue(int a)
    {
        System.out.println("displayValue(int a) has been called : " + a);
    }

    public void displayValue(int a, int b)
    {
        System.out.println("displayValue(int a,int b) : " + a + "," + b);
    }

}

Output

displayValue(String str) has been called : Hello
displayValue(int a) has been called : 10
displayValue(int a,int b) : 200,400

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

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

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/2f20a20e875ab6e7de15adc0041c373263d61c3b/BasicJava/OverloadedMethodDemoApp/?at=master

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JAVA Tutorial

Java Tutorial : Java Access modifiers private and public

Click here to watch in Youtube :
https://www.youtube.com/watch?v=SotFxl07eAM&list=UUhwKlOVR041tngjerWxVccw

Student.java

public class Student
{
    /*
     * public modifier — the field is accessible from all classes.
     */
    public String name;
    
    /*
     * private modifier—the field is accessible only within its own class.
     */
    private int age;

}

StudentDemoTest.java

public class StudentDemoTest
{

    public static void main(String[] args)
    {
        Student student = new Student();
        student.name = "Dave";
        student.age = 23;
    }

}

Output

Exception in thread "main" java.lang.Error: Unresolved compilation problem: 
    The field Student.age is not visible

    at StudentDemoTest.main(StudentDemoTest.java:8)

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

Github Link:
https://github.com/ramram43210/Java/tree/master/BasicJava/AccessModifiersDemoPrivate-PublicApp

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/2f20a20e875ab6e7de15adc0041c373263d61c3b/BasicJava/AccessModifiersDemoPrivate-PublicApp/?at=master

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JAVA Tutorial

Java Tutorial : Java Access modifiers Getter and Setter Methods

Click here to watch in Youtube :
https://www.youtube.com/watch?v=L5q_B2AycJg&list=UUhwKlOVR041tngjerWxVccw&index=14

Student.java

public class Student
{

    /*
     * private modifier—the field is accessible only within its own class.
     * 
     * In the spirit of encapsulation, it is common to make fields private. This
     * means that they can only be directly accessed from the Student class. We
     * still need access to these values, however. This can be done indirectly
     * by adding public methods that obtain the field values for us:
     */

    private String name;
    private int age;

    public String getName()
    {
        return name;
    }

    public void setName(String name)
    {
        this.name = name;
    }

    public int getAge()
    {
        return age;
    }

    public void setAge(int age)
    {
        this.age = age;
    }

}

StudentDemoTest.java

public class StudentDemoTest
{

    public static void main(String[] args)
    {
        Student student = new Student();
        student.setName("Dave"); 
        student.setAge(23);
        
        System.out.println("Name : "+student.getName());
        System.out.println("Age  : "+student.getAge());
    }

}

Output

Name : Dave
Age  : 23

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

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

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/2f20a20e875ab6e7de15adc0041c373263d61c3b/BasicJava/AccessModifiersDemoGetterSetterApp/?at=master

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JAVA Tutorial

Java Tutorial : Java return Statement

Click here to watch in Youtube :
https://www.youtube.com/watch?v=9Njpp8-StJM&list=UUhwKlOVR041tngjerWxVccw

ReturnDemo.java

public class ReturnDemo
{
    public static void main(String[] args)
    {

        /*
         * The return statement exits from the current method, and control flow
         * returns to where the method was invoked.
         * 
         * The return statement has two forms: one that returns a value, and one
         * that doesn't.
         * 
         * To return a value, simply put the value (or an expression that
         * calculates the value) after the return keyword.
         */

        ReturnDemo returnDemo = new ReturnDemo();
        int totalValue = returnDemo.getTotal(10, 10);
        System.out.println("totalValue : " + totalValue);

    }

    public int getTotal(int a, int b)
    {
        int c = a + b;
        /*
         * The data type of the returned value must match the type of the
         * method's declared return value.
         */
        return c;
    }

}

Output

totalValue : 20

ReturnVoidDemo.java

public class ReturnVoidDemo
{
    public static void main(String[] args)
    {

        /*
         * The return statement exits from the current method, and control flow
         * returns to where the method was invoked.
         * 
         * The return statement has two forms: one that returns a value, and one
         * that doesn't.
         * 
         * To return a value, simply put the value (or an expression that
         * calculates the value) after the return keyword.
         */

        ReturnVoidDemo returnVoidDemo = new ReturnVoidDemo();
        returnVoidDemo.calculateTotal(0, 0);
        System.out.println("End---");

    }

    public void calculateTotal(int a, int b)
    {

        if (a == 0 && b == 0)
        {
            /*
             * When a method is declared void, use the form of return that
             * doesn't return a value.
             */
            System.out
                    .println("Both a and b are '0',So current method will exist");
            return;
        }

        int totalValue = a + b;
        System.out.println("totalValue :" + totalValue);
    }

}

Output

Both a and b are '0',So current method will exist
End---

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

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

Bitbucket Link:
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JAVA Tutorial

Java Tutorial : Java Break with Label(Array search)

Click here to watch in Youtube :
https://www.youtube.com/watch?v=XHbrM7iNO8E&list=UUhwKlOVR041tngjerWxVccw

BreakWithLabelDemo.java

class BreakWithLabelDemo
{
    public static void main(String[] args)
    {

        /*
         * An unlabeled break statement terminates the innermost switch, for,
         * while, or do-while statement, but a labeled break terminates an outer
         * statement.
         */

        int[][] arrayOfInts =
        {
        { 1, 2, 3 },
        { 4, 5, 6 },
        { 7, 8, 9 } };

        int searchfor = 2;

        int i;
        int j = 0;
        boolean foundIt = false;

        search: for (i = 0; i < arrayOfInts.length; i++)
        {
            System.out.println("i:" + i);
            for (j = 0; j < arrayOfInts[i].length; j++)
            {
                System.out.println("arrayOfInts[" + i + "]" + "[" + j + "] : "
                        + arrayOfInts[i][j]);
                if (arrayOfInts[i][j] == searchfor)
                {
                    foundIt = true;
                    break search;
                }
            }
            System.out.println("for loop j is completed.");
        }

        System.out.println("for loop i is completed.");

        if (foundIt)
        {
            System.out.println("Found " + searchfor + " at " + i + ", " + j);
        }
        else
        {
            System.out.println(searchfor + " not in the array");
        }

    }
}

Output

i:0
arrayOfInts[0][0] : 1
arrayOfInts[0][1] : 2
for loop i is completed.
Found 2 at 0, 1

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

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

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/2f20a20e875ab6e7de15adc0041c373263d61c3b/BasicJava/ControlFlowDemoBreakLabelArrayApp/?at=master

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JAVA Tutorial

Friday, 20 November 2015

Java Tutorial : Java Continue Statement with Label

Click here to watch in Youtube :
https://www.youtube.com/watch?v=fTMVHrSm9nI&list=UUhwKlOVR041tngjerWxVccw

ContinueDemo.java

public class ContinueDemo
{
    public static void main(String[] args)
    {

        /*
         * The continue statement skips the current iteration of a for, while ,
         * or do-while loop. The unlabeled form skips to the end of the
         * innermost loop's body and evaluates the boolean expression that
         * controls the loop.
         */

        for (int i = 0; i < 2; i++)
        {
            System.out.println("i : " + i + "\n");
            for (int j = 0; j < 3; j++)
            {
                if (j == 1)
                {
                    continue;
                }
                System.out.println("j : " + j);
            }

            System.out.println("------------------------------");
        }

    }
}

Output

i : 0

j : 0
j : 2
------------------------------
i : 1

j : 0
j : 2
------------------------------

ContinueWithLabelDemo.java

public class ContinueWithLabelDemo
{
    public static void main(String[] args)
    {

        /*
         * A labeled continue statement skips the current iteration of an outer
         * loop marked with the given label.
         */

        outer: for (int i = 0; i < 2; i++)
        {
            System.out.println("\n" + "i : " + i + "\n");
            for (int j = 0; j < 3; j++)
            {
                if (j == 1)
                {
                    continue outer;
                }
                System.out.println("j : " + j);
            }

            System.out.println("------------------------------");
        }

    }
}