Modifying scope of member variables

Design Patterns/src/composite/Song.java

@@ -2,9 +2,9 @@ package composite;
 
 public class Song extends SongComponent {
 
-    String songName;
-    String bandName;
-    int releaseYear;
+    private final String songName;
+    private final String bandName;
+    private final int releaseYear;
 
     public Song(String songName, String bandName, int releaseYear){
         this.songName = songName;

Design Patterns/src/composite/SongIterator.java

@@ -4,7 +4,7 @@ import java.util.Iterator;
 import java.util.List;
 
 public class SongIterator implements Iterator<SongComponent> {
-    List<SongComponent> playList;
+    private final List<SongComponent> playList;
     private int currentIndex = 0;
 
     public SongIterator(List<SongComponent> playList) {