Difference Between Information Hiding and Encapsulation (#14886)

* Difference Between Information Hiding and Encapsulation

* Difference Between Information Hiding and Encapsulation

core-java-modules/core-java-lang-oop-others/src/main/java/com/baeldung/encapsulation/Book.java

@@ -0,0 +1,7 @@
+package com.baeldung.encapsulation;
+
+public class Book {
+    public String author;
+    public int isbn;
+
+}

core-java-modules/core-java-lang-oop-others/src/main/java/com/baeldung/encapsulation/BookDetails.java

@@ -0,0 +1,8 @@
+package com.baeldung.encapsulation;
+
+public class BookDetails {
+
+    public String bookDetails(Book book) {
+        return "author name: " + book.author + " ISBN: " + book.isbn;
+    }
+}

core-java-modules/core-java-lang-oop-others/src/main/java/com/baeldung/encapsulation/BookEncapsulation.java

@@ -0,0 +1,17 @@
+package com.baeldung.encapsulation;
+
+public class BookEncapsulation {
+    public String author;
+    public int isbn;
+    public int id = 1;
+
+    public BookEncapsulation(String author, int isbn) {
+        this.author = author;
+        this.isbn = isbn;
+    }
+
+    public String getBookDetails() {
+        return "author id: " + id + " author name: " + author + " ISBN: " + isbn;
+    }
+
+}

core-java-modules/core-java-lang-oop-others/src/main/java/com/baeldung/encapsulation/BookInformationHiding.java

@@ -0,0 +1,36 @@
+package com.baeldung.encapsulation;
+
+public class BookInformationHiding {
+    private String author;
+    private int isbn;
+    private int id = 1;
+
+    public BookInformationHiding(String author, int isbn) {
+        setAuthor(author);
+        setIsbn(isbn);
+    }
+
+    public String getAuthor() {
+        return author;
+    }
+
+    public void setAuthor(String author) {
+        this.author = author;
+    }
+
+    public int getIsbn() {
+        return isbn;
+    }
+
+    public void setIsbn(int isbn) {
+        if (isbn < 0) {
+            throw new IllegalArgumentException("ISBN can't be negative");
+        }
+        this.isbn = isbn;
+    }
+
+    public String getBookDetails() {
+        return "author id: " + id + " author name: " + author + " ISBN: " + isbn;
+    }
+
+}

core-java-modules/core-java-lang-oop-others/src/test/java/com/baeldung/encapsulation/EncapsulationAndInformationHidingUnitTest.java

@@ -0,0 +1,35 @@
+package com.baeldung.encapsulation;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+public class EncapsulationAndInformationHidingUnitTest {
+
+    @Test
+    public void givenUnencapsulatedClass_whenImplementationClassIsSeparate_thenReturnResult() {
+        Book myBook = new Book();
+        myBook.author = "J.K Rowlings";
+        myBook.isbn = 67890;
+        BookDetails details = new BookDetails();
+        String result = details.bookDetails(myBook);
+        assertEquals("author name: " + myBook.author + " ISBN: " + myBook.isbn, result);
+
+    }
+
+    @Test
+    public void givenEncapsulatedClass_whenDataIsNotHidden_thenReturnResult() {
+        BookEncapsulation myBook = new BookEncapsulation("J.K Rowlings", 67890);
+        String result = myBook.getBookDetails();
+        assertEquals("author id: " + 1 + " author name: " + myBook.author + " ISBN: " + myBook.isbn, result);
+    }
+
+    @Test
+    public void givenEncapsulatedClass_whenDataIsHidden_thenReturnResult() {
+        BookInformationHiding myBook = new BookInformationHiding("J.K Rowlings", 67890);
+        String result = myBook.getBookDetails();
+        assertEquals("author id: " + 1 + " author name: " + myBook.getAuthor() + " ISBN: " + myBook.getIsbn(), result);
+    }
+
+}