Java language basics: Internal classes

1. Common internal class
The simplest example of a common internal class is as follows:
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// External class
Class OutterClass {
// Internal class
Public class InnerClass {
Private int I = 0;
Public int getInt (){
Return I;
}
}
Public void proc (){
InnerClass inClass = new InnerClass ();
System. out. println (inClass. getInt ());
}
}

Public class Main {
Public static void main (String [] args ){
OutterClass outClass = new OutterClass ();
OutClass. proc ();
}
}
// External class
Class OutterClass {
// Internal class
Public class InnerClass {
Private int I = 0;
Public int getInt (){
Return I;
}
}
Public void proc (){
InnerClass inClass = new InnerClass ();
System. out. println (inClass. getInt ());
}
}
 
Public class Main {
Public static void main (String [] args ){
OutterClass outClass = new OutterClass ();
OutClass. proc ();
}
}
The external class can access the Private Members of the internal class, and the internal class can also access the private members of the external class:
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// External class
Class OutterClass {
Private int mOut = 10;
// Internal class
Public class InnerClass {
Private int mIn = 0;
Public void printOutPrivate (){
// Print external class members directly
System. out. println (mOut );
}
}
Public void printInPrivate (){
InnerClass inClass = new InnerClass ();
// Directly print Private Members of the internal class
System. out. println (inClass. mIn );
}
Public void printOutPrivate (){
InnerClass inClass = new InnerClass ();
InClass. printOutPrivate ();
}
}

Public class Main {
Public static void main (String [] args ){
OutterClass outClass = new OutterClass ();
OutClass. printInPrivate ();
OutClass. printOutPrivate ();
}
}
// External class
Class OutterClass {
Private int mOut = 10;
// Internal class
Public class InnerClass {
Private int mIn = 0;
Public void printOutPrivate (){
// Print external class members directly
System. out. println (mOut );
}
}
Public void printInPrivate (){
InnerClass inClass = new InnerClass ();
// Directly print Private Members of the internal class
System. out. println (inClass. mIn );
}
Public void printOutPrivate (){
InnerClass inClass = new InnerClass ();
InClass. printOutPrivate ();
}
}
 
Public class Main {
Public static void main (String [] args ){
OutterClass outClass = new OutterClass ();
OutClass. printInPrivate ();
OutClass. printOutPrivate ();
}
}
If the name of the member variable of the external class is the same as that of the internal class, when the internal class wants to access this member of the external class, you can use "OutClass. this. mem" to distinguish:
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// External class
Class OutterClass {
Private int mMem = 10;
// Internal class
Public class InnerClass {
Private int mMem = 0;
Public void printOutPrivate (){
// Print external class members directly
System. out. println (OutterClass. this. mMem );
}
}
}
// External class
Class OutterClass {
Private int mMem = 10;
// Internal class
Public class InnerClass {
Private int mMem = 0;
Public void printOutPrivate (){
// Print external class members directly
System. out. println (OutterClass. this. mMem );
}
}
}
To create a common internal class, you must first create the corresponding external class:
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// External class
Class OutterClass {
Private int mMem = 10;
// Internal class
Public class InnerClass {
Private int mMem = 0;
Public void printOutPrivate (){
// Print external class members directly
System. out. println (OutterClass. this. mMem );
}
& Nb