Usage of static with inner classes

[Sekhar Choudary]

Hi,

class Outer1{
String ov="outer1 var";
Inner1 iob=new Inner1();
class Inner1{
Inner1(){ System.out.println("Inner1 cons"); }
public void im1(){ System.out.println("inner1 method im1::"+ov+" "+iv); }//im1
String iv="inner var";
}//inner1
public static void om1()
{ System.out.println("Outer1 method om1");
//new Inner1().im1(); line #1
// or even for
//Inner1 o=new Inner1(); o.im1(); same error line #2
}

public static void main(String[] args){
Outer1.Inner1 ob=new Outer1().new Inner1();
ob.im1();
om1();
Outer1 o=new Outer1();
o.om1();
}//main
}//class

Hi when i compile the above source code,compiler is pointing out two errors each at line#1 and line# 2 as follows
" Non static variable this cannot be referenced from static context"

Can't we access the instance method from static method using object of that class??

Thanks.

[Sagar Rohankar]

The error explains it all, In static methods, Java allowed to give access to only static members . So to run this code, make your im1() method a static one ! and please use code tags to surround tho code snippet !

[Vlado Zajac]

Instance of outer class is required to create an instance of inner class.

So it static method you cannot use

new Inner1()

but something like this is needed:

new Outer1().new Inner1()

[Raphael Rabadan]

Originally posted by Vlado Zajac:
Instance of outer class is required to create an instance of inner class.

So it static method you cannot use

new Inner1()

but something like this is needed:

new Outer1().new Inner1()

Just an adittion, you could make this code work making the method an instance method.

Take a look at this code:

class Outer1 {
String ov = "outer1 var";
Inner1 iob = new Inner1();
 
class Inner1 {
Inner1() {
System.out.println("Inner1 cons");
}
 
public void im1() {
System.out.println("inner1 method im1::" + ov + " " + iv);
}
 
String iv = "inner var";
}
 
// Instance Method
public void om1() {
System.out.println("Outer1 method om1");
new Inner1().im1();
Inner1 o = new Inner1();
o.im1();
}
 
// Static Method
public static void om2() {
new Outer1().new Inner1().im1();
Outer1 o = new Outer1();
o.new Inner1().im1();
}
}