I've been trying to understand scoping in Java, more precisely, when it comes to having inner classes.
I have the following snipped of code:
import javax.swing.*;
public class OuterClass {
// Constructor
public OuterClass() {
}
public static void main(String[] args) {
OuterClass app = new OuterClass();
app.doStuff();
}
private void doStuff(){
System.out.print("\033[H\033[2J"); // DEBUG clear out output
InnerClass newNote = new InnerClass("images/01-SOL.png");
// QUESTION: why are the following working and accessible??
ImageIcon myIcon = newNote.getIcon();
System.out.println(myIcon.getImage());
System.out.println(newNote.iconPath);
}
// define private inner class
private class InnerClass {
private String iconPath;
private InnerClass(String iconPath){
this.iconPath = iconPath;
}
private ImageIcon getIcon(){
return new ImageIcon(this.iconPath);
}
}
}
I have an Outer class, and within it, an Inner class. As per my question in code, I do not understand WHY the private members of InnerClass (whether properties, or functions) are accessible from OUTSIDE the inner class, meaning in my example, in my outer class.
I'm writing another small swing app, almost done, but am just lost in what scoping I should be using in my Inner classes...
I was expecting to have to
- set the inner class itself to private (thus only accessible to the outer class).
- set the inner class members to private (thus only the inner class itself could access them)
- set the inner class getter/setter functions to public, so that the outer class could access them ...
Doesn't seem to work at all this. I'm puzzled...
Could anyone shed a light on this from my example?
Much much thanks!
==========
UPDATE:
And so we're clear why an inner class... My project is a swing app that shows random music notes. Each note "Note" has a few properties (index, image file, icon, finally, it has an ArrayList of object of type from another inner class "PositionCombi").
The NotePosition class has a positionNum, fingerNum, and stringNum..
Here's the bulk of it:
public class OuterClass {
private String[] allNoteNames = ["C","D","E","F","G","A","B"];
private Note noteImages[];
public OuterClass {
initNotes();
doStuff();
}
private void initNotes(){
this.noteImages = new Note[19];
noteImages[0] = new Note(4, "images/01-SOL.png");
noteImages[0].addPositionCombi(1, 0, 4);
noteImages[0].addPositionCombi(2, 3, 4);
noteImages[0].addPositionCombi(3, 2, 4);
//...etc.
}
private Note getShuffledNote(){
//... return a random note object from this.noteImages
}
private void doStuff() {
// get a suffled note:
Note workingNote = getShuffledNote();
lblNoteName.setText( this.allNoteNames[ workingNote.getIndex ] );
lblImage.setIcon( workingNote.getIcon() );
ArrayList<Note.PositionCombi> notePositions = workingNote.getPositions()
//print positions for given note:
for (Note.PositionCombi notePosCombi : notePosCombinations) {
System.out.println( "Position: " + notePosCombi.getPositionNum() );
System.out.println( "Finger: " + notePosCombi.getFingerNum() );
System.out.println( "String: " + notePosCombi.getStringNum() );
}
}
/*** INNER CLASS DEFS ***********/
private class Note { // inner Note class
private int noteIndex;
private String iconPath;
private ArrayList<PositionCombi> PositionCombis;
private Note(int noteIndex, String iconPath){
this.noteIndex = noteIndex;
this.iconPath = iconPath;
this.PositionCombis = new ArrayList<PositionCombi>();
}
private int getNoteIndex(){
return this.noteIndex;
}
private ImageIcon getIcon(){
return new ImageIcon(this.iconPath);
}
private ArrayList<PositionCombi> getPositionCombis(){
return this.PositionCombis;
}
private void addPositionCombi(int positionNum, int fingerNum, int stringNum){
this.PositionCombis.add(new PositionCombi(positionNum, fingerNum, stringNum));
}
private class PositionCombi { // inner-INNER PositionCombination class
private int positionNum;
private int fingerNum;
private int stringNum;
private PositionCombi(int positionNum, int fingerNum, int stringNum){
this.positionNum = positionNum;
this.fingerNum = fingerNum;
this.stringNum = stringNum;
}
private int getPositionNum(){
return this.positionNum;
}
private int getFingerNum(){
return this.fingerNum;
}
private int getStringNum(){
return this.stringNum;
}
}
}
}
