review modifications

core-java-modules/core-java-lang-oop-2/src/main/java/com/baeldung/accessmodifiers/publicmodifier/ListOfThree.java

@@ -0,0 +1,31 @@
+package com.baeldung.accessmodifiers.publicmodifier;
+
+import java.util.AbstractList;
+
+public class ListOfThree<E> extends AbstractList<E> {
+
+    private static final int MAX_LENGTH = 3;
+    private int size;
+    private Object[] elements = new Object[MAX_LENGTH];
+    
+    @Override
+    @SuppressWarnings("unchecked")
+    public E get(int index) {        
+        return (E)elements[index];
+    }
+
+    @Override
+    public boolean add(E e) {
+        
+        elements[size] = e;
+        size++;
+        
+        return true;
+    }
+    
+    @Override
+    public int size() {
+        return size;
+    }
+
+}

core-java-modules/core-java-lang-oop-2/src/main/java/com/baeldung/accessmodifiers/publicmodifier/Student.java

@@ -1,4 +1,4 @@
-package com.baeldung.accessmodifiers;
+package com.baeldung.accessmodifiers.publicmodifier;
 
 import java.math.BigDecimal;
 import java.sql.Connection;
@@ -7,12 +7,16 @@ import java.sql.SQLException;
 
 public class Student {
 
-    private BigDecimal grades; //new representation
+    private BigDecimal grade; //new representation
     private String name;   
     private int age;
 
-    public int getGrades() {
+    public int getGrade() {
-        return grades.intValue(); //Backward compatibility
+        return grade.intValue(); //Backward compatibility
+    }
+    
+    public BigDecimal bigDecimalGrade() {
+        return grade;
     }
     
     public Connection getConnection() throws SQLException {
@@ -21,10 +25,6 @@ public class Student {
         return DriverManager.getConnection(URL, "sa", "");
 
     }
-    
-    public BigDecimal bigDecimalGrades() {
-        return grades;
-    }
         
     public void setAge(int age) {
         if (age < 0 || age > 150)

core-java-modules/core-java-lang-oop-2/src/test/java/com/baeldung/accessmodifiers/PublicAccessModifierUnitTest.java

@@ -3,34 +3,76 @@ package com.baeldung.accessmodifiers;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.TestInstance;
 import org.junit.jupiter.api.TestInstance.Lifecycle;
+import com.baeldung.accessmodifiers.publicmodifier.ListOfThree;
 import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 import java.math.BigDecimal;
 import java.sql.Connection;
 import java.sql.DriverManager;
 import java.sql.SQLException;
+import java.util.List;
 
 @TestInstance(Lifecycle.PER_CLASS)
 public class PublicAccessModifierUnitTest {
 
     @Test
-    public void whenUsingIntValue_valuesAreEqual() {
+    public void whenUsingBigDecimalIntValueMethod_correspondingIntIsReturned() {
-        
+        assertEquals(0, new BigDecimal(0).intValue()); //instance member
-        assertEquals(0, new BigDecimal(0).intValue());
     }
-
+    
     @Test
-    public void whenUsingToLowerCase_valuesAreEqual() {
+    public void whenUsingIntegerMaxValueField_maxPossibleIntValueIsReturned() {
-        
+        assertEquals(2147483647, Integer.MAX_VALUE); //static field
+    }
+    
+    @Test
+    public void whenUsingStringToLowerCase_stringTurnsToLowerCase() {
         assertEquals("alex", "ALEX".toLowerCase());
     }
 
+    @Test
+    public void whenParsingStringOne_parseIntReturns1() {
+        assertEquals(1, Integer.parseInt("1"));
+    }
+    
     @Test
     public void whenConnectingToH2_connectionInstanceIsReturned() throws SQLException {
 
-        final String URL = "jdbc:h2:~/test";
+        final String url = "jdbc:h2:~/test";
-        Connection conn = DriverManager.getConnection(URL, "sa", "");
+        Connection conn = DriverManager.getConnection(url, "sa", "");
         assertNotNull(conn);
     }
 
+    @Test
+    public void whenCreatingCustomList_concreteAndInheritedMethodsWork() {
+
+        List<String> list1 = new ListOfThree<String>();
+        list1.add("zero"); //inherited implementation
+        list1.add("one");
+        list1.add("two");
+        
+        //our implemented methods
+        assertEquals("zero", list1.get(0));
+      
+        assertThrows(ArrayIndexOutOfBoundsException.class, () -> {
+            list1.get(4);
+        });
+        
+        assertThrows(ArrayIndexOutOfBoundsException.class, () -> {
+            list1.add("three");
+        });
+        
+        assertEquals(3, list1.size());
+
+        list1.indexOf("one"); //inherited implementation
+        
+        List<String> list2 = new ListOfThree<String>();
+        list2.add("zero");
+        list2.add("one");
+        
+        assertTrue(list1.containsAll(list2));  //inherited implementation
+    }
+    
 }