YouTipJava Inner Class
# Java Inner Class
[ Java Objects and Classes](#)
In this chapter, we will learn about Java inner classes.
A class can be nested within another class in Java. The syntax is as follows:
class OuterClass { // Outer class // ... class NestedClass { // Nested class, also known as inner class // ... }}
To access the inner class, you can create an object of the outer class, and then create an object of the inner class.
There are two types of nested classes:
* Non-static inner class
* Static inner class
### Non-static Inner Class
A non-static inner class is a class nested within another class. It has access to the members of the outer class and is commonly referred to as an inner class.
Since the inner class is nested within the outer class, you must first instantiate the outer class, and then create an object of the inner class.
## Example
class OuterClass {
int x =10;
class InnerClass {
int y =5;
}
}
public class MyMainClass {
public static void main(String[] args){
OuterClass myOuter =new OuterClass();
OuterClass.InnerClass myInner = myOuter.new InnerClass();
System.out.println(myInner.y+ myOuter.x);
}
}
The output of the above example is:
15
### Private Inner Class
Inner classes can be modified with `private` or `protected`. If you do not want the inner class to be accessed by the outer class, you can use the `private` modifier:
## Example
class OuterClass {
int x =10;
private class InnerClass {
int y =5;
}
}
public class MyMainClass {
public static void main(String[] args){
OuterClass myOuter =new OuterClass();
OuterClass.InnerClass myInner = myOuter.new InnerClass();
System.out.println(myInner.y+ myOuter.x);
}
}
In the above example, `InnerClass` is set as a private inner class. Executing it will result in an error:
MyMainClass.java:12: error: OuterClass.InnerClass has private access in OuterClass OuterClass.InnerClass myInner = myOuter.new InnerClass(); ^
### Static Inner Class
A static inner class can be defined using the `static` keyword. We do not need to create an object of the outer class to access a static inner class; it can be accessed directly:
## Example
class OuterClass {
int x =10;
static class InnerClass {
int y =5;
}
}
public class MyMainClass {
public static void main(String[] args){
OuterClass.InnerClass myInner =new OuterClass.InnerClass();
System.out.println(myInner.y);
}
}
The output of the above example is:
5
**Note:** A static inner class cannot access the members of the outer class.
### Accessing Outer Class Members from Inner Class
An advanced use of inner classes is that they can access the properties and methods of the outer class:
## Example
class OuterClass {
int x =10;
class InnerClass {
public int myInnerMethod(){
return x;
}
}
}
public class MyMainClass {
public static void main(String[] args){
OuterClass myOuter =new OuterClass();
OuterClass.InnerClass myInner = myOuter.new InnerClass();
System.out.println(myInner.myInnerMethod());
}
}
The output of the above example is:
10
[ Java Objects and Classes](#)