gjesp

src/main/java/lecture5/objects/Book.java

 package lecture5.objects;
 
-public class Book {
+public class Book implements Comparable<Book>{
 
     String title;
     String author;
@@ -14,8 +14,29 @@ public class Book {
         return String.format("%s - %s", this.title, this.author);
     }
 
-    public boolean equals(Object obj){
-        
+    @Override
+    public boolean equals(Object obj) {
+        if(this == obj) {
+            return true;
+        }
+
+        if(obj instanceof Book){
+            Book toCompare = (Book)obj;
+            if(this.author.equals(toCompare.author) && this.title.equals(toCompare.title)) {
+                return true;
+            }
+        }
+        return false;
     }
-    
-}
+
+    @Override
+    public int compareTo(Book arg0) {
+        int cmp =  this.author.compareTo(arg0.author);
+        if(cmp == 0){
+            return this.title.compareTo(arg0.title);
+        }
+        else{
+            return cmp;
+        }
+    }    
+}
\ No newline at end of file

src/main/java/lecture5/objects/CompareTitle.java

+package lecture5.objects;
+
+import java.util.Comparator;
+
+public class CompareTitle implements Comparator<Book>{
+
+    @Override
+    public int compare(Book arg0, Book arg1) {
+        return arg0.title.compareTo(arg1.title);
+    }
+}

src/main/java/lecture5/objects/Library.java

 package lecture5.objects;
 
 import java.util.ArrayList;
+import java.util.Collections;
 
 public class Library {
     
@@ -43,6 +44,17 @@ public class Library {
         Book wanted = new Book("Hvordan være tøff", "Anders");
         System.out.println(myBooks.hasBook(wanted));
 
+        myBooks.add(new Book("Dyr", "Tommy"));
+        myBooks.add(new Book("Klima", "Susanne"));
+        myBooks.add(new Book("Biler", "Ida"));
+        myBooks.add(new Book("Andre ting", "Anders"));
+
+
+        Collections.sort(myBooks.books);
+        System.out.println(myBooks.books);
+
+        Collections.sort(myBooks.books, new CompareTitle());
+        System.out.println(myBooks.books);
     }
 
     

src/main/java/lecture5/objects/UseCollections.java

+package lecture5.objects;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Random;
+
+public class UseCollections {
+    public static void main(String[] args) {
+        Collection<Integer> tall = getCollection(10);
+        System.out.println(tall);
+        Integer smallest = Collections.min(tall);
+        System.out.println(smallest);
+        ArrayList<Integer> listOfNumbers = new ArrayList<>(tall);
+        Collections.sort(listOfNumbers);
+        System.out.println(listOfNumbers);
+        int count = Collections.frequency(tall, smallest);
+        System.out.println(smallest + " occur " +count+ " times");
+
+    }
+    private static Collection<Integer> getCollection(int numElem){
+        ArrayList<Integer> list = new ArrayList<>();
+
+        Random rand = new Random();
+        for(int i=0; i<numElem; i++) {
+            list.add(rand.nextInt(10));
+        }
+        return list;
+    }
+    
+}