Difference between revisions of "Java/C2/Constructor-overloading/English-timed"

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|   In this tutorial we will learn  

 

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| what is '''constructor overloading'''

 

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| And to overload '''constructor'''

 

 

 

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|   Here we are using  

 

* Ubuntu version 11.10 OS

* Java Development kit 1.6

* Eclipse 3.7.0   

 

 

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| To follow this tutorial you must know  

 

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| how to create '''constructors''' in '''java''' using '''eclipse'''.

 

 

| If not, for relevant tutorials please visit our website which is as shown,

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| What is constructor overloading?

| Define multiple '''constructors''' for a class.  

| In '''eclipse''', I have a class '''Student''' with two variables and a method.

| So type, '''''Student '''within''' '''parentheses''' int number '''comma''' String the_name.'''''

 

| ''Within''' '''curly''' '''brackets''', type roll_number '''is''' '''equal''' '''to''' number.'''''

 

| And''''' name '''is equal to '''the_name'''''

 

 

| So we have a '''constructor''' with two parameters.

|  let us call this '''constructor'''.

 

| So in '''main method''' type '''''new Student '''parentheses semi colon''

| So we need to   pass '''arguments'''.

 

| So within parentheses type '''''22''''' ''comma'' ''in double quotes'' '''''Ram'''''.

 

|   Let us call the method.

 

| So before '''new '''type''' Student s '''''is equal to''' new student'''.

| Now using the object '''s''' we will call the method  ''' studentDetail()'''

|  We see the output '''22''' and '''Ram.'''

| Now''''' '''''let us define a''''' ''' constructor''' with no parameter.

 

| So type, '''''Student '''parentheses.''

 

| ''Within''' '''curly''' '''brackets''' roll_number '''is equal to''' 0.'''''

 

| And''''' name '''is''' '''equal''' '''to''' '''in''' '''double''' '''quotes''' '''hypen'' that is no name

|  So now we can call the '''constructor''' with no parameters.

 

| So type'' '''Student''' '''s1''' is equal to '''new''' '''Student''' parentheses'' semicolon.

|  This time we see no error, since we have define a constructor without parameter

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| Then''''' s1 '''dot''' studentDetail'''''.

| So in  the output  we see '''zero''' and '''dash''' when the '''default''' '''constructor''' is called.

 

| We have two '''constructor''' with different parameter.

 

| Both the '''constructor''' obviously have same name.

 

| So depending on the type and number of parameter, the '''constructor''' is called.  

|   Let us see the advantage of '''constructor''' overloading.

 

| Suppose now call a constructor with two parameters.

 

| So type '''''Student s3= new Student();'''''

 

| Now within parentheses,  suppose i gave the '''name''' argument first and then the '''roll''' '''number.'''

| let see what happens.

 

| So in ''double quotes '''Raju''' comma '''45'''''

|  We see an error which states that the '''constructor student with the parameter  String comma int is undefined.'''

|  So let us define the constructor.

| So type '''''Student''' within parentheses '''String''' '''the_name''' comma '''int''' '''r_no'''''

|So over here first parameter is '''string'' and the second parameter is '''int'''

|Then '''Within curly bracket, '''roll_number''' is equal to '''r_no.'''''

| And'' '''name''' is equal to '''the_name.'''''

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| Let us call the method.

| So '''''s3''''' ''dot'' '''''studentDetail.'''''

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

|So we see the output'''45''' and '''Raju'''   

| So here we see that when we call the '''constructor'''.

| We do not have to worry about the parameters that we are passing.

| This is simply because we have define multiple '''constructor''' with different parameters.

| So the proper '''constructor''' is '''overloaded.'''

|   06:57

| So type '''''Student''' within parentheses''' int num'''.''

| '' within curly brackets '''roll_number '''is equalto '''num'''.''

| ''And '''name''' is equal to   '''no''' '''name'''.''

| Now  let us call this  '''constructor'''   

| So type '''''Student''''' '''''s4''''' ''is'' ''equalto'' '''''new''''' '''''Student''''' this time we will pass an  single argument. So let us pass '''''61'''''

| Then '''''s4 '''dot''' studentDetail '''''

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

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| So in the output we see  the '''roll''' '''number''' as '''61''' and '''name''' as '''no''' '''name.'''

| As we can see, the proper overloaded '''constructor''' is called when new is executed.  

| Based upon the parameters specified the proper '''constructor''' is overloaded.  

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|   So in this tutorial, we have learnt  

| About the  '''constructor overloading.'''

|   to overload '''constructor''' and the use of constructor overloading

| For self assessment, create multiple constructors for class '''Employee'''and   Overload the '''constructor.'''  

 

 

 

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