Nested/Inner classes Example program

[hardikjava shah]

Hi, I created a small test program to learn Nested/Inner classes. Thought of sharing with you all. You can tweak it and see results for yourself. Also, let me know if you think I have missed anything.

interface forAnonymousInner{
void testMethod();
}
 
public class Program1 {
private int x = 7;

//Static inner class
static class staticnestedclass{
void testmethod(){
System.out.println("Printing from static nester class!");
}
}

//Regular inner class
class Program1Inner {
public void seeOuter()
{
System.out.println("Program1 x value is " + x);
}
}

//Passing parameter
public void runanonyparam(forAnonymousInner ano)
{
ano.testMethod();
}

public void classInnerClassMethod()
{
final String z = "test";

//Local inner class
class Program1Inner1{
public void seeOuter()
{
System.out.println("Printing from Local Inner Class method value of Program1" + x + " local inner class can only refer to final local variables " + z);
}
}
Program1Inner1 pi1 = new Program1Inner1();
pi1.seeOuter();
}

public static void main(String args[])
{
//2 ways to initialize
Program1.Program1Inner innerobject = new Program1().new Program1Inner();

Program1 prg1 = new Program1();
Program1.Program1Inner innerobject1 = prg1.new Program1Inner();

innerobject.seeOuter();
innerobject1.seeOuter();

//Local inner class method
prg1.classInnerClassMethod();

//Anonymous inner class method 1
program2anonymousinnerclass pg2 = new program2anonymousinnerclass();

//Anonymous inner class method 2
program3anonymousinnerclassinterface pg3 = new program3anonymousinnerclassinterface();

pg2.prg1.classInnerClassMethod();
pg3.anyitf.testMethod();

//Anoymous object as method param
prg1.runanonyparam(new forAnonymousInner(){
public void testMethod()
{
System.out.println("Passing anonymous innerclass as method argument!");
}
});

staticnestedclass snc = new staticnestedclass();
snc.testmethod();
}
}
 
//Anonymous inner class extending class
class program2anonymousinnerclass
{
Program1 prg1 = new Program1(){
public void classInnerClassMethod()
{
System.out.println("This from anonumous class extended from Program1");
}
};
}
 
//Anonymous inner class extending interface
class program3anonymousinnerclassinterface
{
forAnonymousInner anyitf = new forAnonymousInner(){
public void testMethod(){
System.out.println("From implementing anonymous inner class from interface");
}
};
}
 

[HENRY: Added Code Tags]
[ December 09, 2006: Message edited by: Henry Wong ]

[Rancy Chadha]

Hi Hardik,

Just want to do a little correction about the comment you wrote above the method
//Static inner class
static class staticnestedclass
{
void testmethod(){
System.out.println("Printing from static nester class!");}
}

The nested classes which are declared as static are NOT INNER classes. They are just termed as static nested classes.

Classes which fall under inner classes are:
nonstatic nested classes
local classes
anonymous class

The code you have written is good but I wanted to suggest you that you missed to show an example of local class nested in static method if I am not mistaken.

Thanks,
Rancy

[Barry Gaunt]

Time to look at our JavaRanch Naming Policy again. Hardik, please remove the "java" from your display name.
Thanks,
-Barry