Difference between revisions of "Java/C2/Default-constructor/English-timed"

|  Welcome to the Spoken Tutorial on '''Default constructor''' in''' java'''.

|  In this tutorial, we will learn:

| About the default constructor.   

|And  to create a constructor.  

| Here we are using:

'''Ubuntu version 11.10'''

'''Java Development Environment jdk 1.6''' and  

'''Eclipse 3.7.0'''

|  To follow this tutorial, you must know  

| how to create a '''class''' and the '''object''' of the class in java using '''eclipse'''.

| If not, for relevant tutorials, please visit our website which is as shown.http://www.spoken-tutorial.org  

|  '''Constructor''' is used to initialize the '''instance''' variables.

|  Let us now see how a '''constructor''' is defined in java.

| So, in the '''eclipse''', I have already created a java file '''Student.java'''.

|  In the '''Student''' '''class''' we will declare two variables.

| So type '''int''' '''roll_number''' semi-colon and '''String''' '''name''' semicolon.  

| So, type: '''void''' '''studentDetail()'''.

| Within curly brackets, type: '''System''' dot '''out''' dot '''println''' '''roll_number;'''

| Then '''System''' dot '''out''' dot '''println''' '''name;'''.

|  Now in '''main''' '''method''' we will call this method.

| So, let us create an object and call the '''method'''.

| So, type: '''Student''' object name '''stu''' equal to '''new''' '''Student()'''.

| Then '''stu''' dot method name i.e '''studentDetail'''.

|'''Save''' and '''Run '''the program.

| We see the output 'zero' and 'null'.

| So, the '''int''' variable '''roll_number''' has been initialized to its default value 'zero'.

| And the '''String''' '''name''' has been initialized to its default value 'null'.

| If we do not define a '''constructor''' then a default constructor is created.

| Default '''constructor''' has no parameters.

| So, type: '''Student''' S capital parenthesis and curly brackets.

| Remember, the '''Constructor''' has the same name as the 'class name' to which it belongs.

|  Constructors are also similar to '''methods''' but there are some important differences.

| This is because the '''constructor'''  that we defined is same as having no '''constructor.'''

| But here, no default '''constructor''' is created because we have defined a '''constructor.'''

|  Now, let's give values to our variables.

| So, inside the '''constructor''' type: '''roll_number''' equal to ten semicolon.

| And '''name''' equal to within double quotes '''Raman'''.

|  We see in the output that the '''roll_number''' is '''ten''' and the '''name''' is Raman.

| So, the '''constructor''' initializes the '''instance field'''.

|  Now, let us see some differences between  '''method''' and a '''constructor'''.

| '''Constructor''' does not have  a '''return''' type.

|whereas '''method''' has a return type.

|whereas the  '''method''' is called using the '''dot''' operator.

| So, these were some differences between '''constructor''' and '''method.'''

| So, in this tutorial, we have learnt:

|About the default '''constructor'''.

|To define a '''constructor'''.

|And Differences between '''method''' and '''constructor.'''

|  For self assessment, create a '''class''' '''Employee''' with variables and a  '''method''' to display variables.

| And create a '''constructor''' for the class '''Employee'''.  

|  To know more about the Spoken Tutorial Project,

|  watch the video available at http://spoken-tutorial.org/What_is_a_Spoken_Tutorial.

 

|  It summarizes the Spoken Tutorial project.

| If you do not have good bandwidth, you can download and watch it.

|  The Spoken Tutorial project team:

| Conducts workshops using spoken tutorials.

|  Gives certificates to those who pass an online test.

|  Spoken Tutorial project is a part of the Talk to a Teacher project.

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|This brings us to the end of the tutorial.

| This is Prathamesh Salunke, signing off.  Jai Hind.