src/main/java/hhn/temp/project/provider/DatabaseManager.java

@@ -10,6 +10,7 @@ public interface DatabaseManager<E> extends Database {
   public void saveObjects(Collection<E> objects) throws SQLException;
   public Collection<E> getObjects() throws SQLException;
   public void saveObject(E object) throws SQLException;
-  public E getObject(int id) throws SQLException;
-  public void deleteObject(int id) throws SQLException;
+  public E getObject(int taskId) throws SQLException;
+  public void deleteObject(int taskId) throws SQLException;
+  public E updateObject(int taskId, E object) throws SQLException;
 }

src/main/java/hhn/temp/project/provider/SimpleDatabaseManager.java

@@ -2,11 +2,11 @@ package hhn.temp.project.provider;
 
 import hhn.temp.project.Task;
 import hhn.temp.project.TaskState;
-import jdk.jshell.spi.ExecutionControl;
 
-import java.io.IOException;
 import java.sql.*;
+import java.util.ArrayList;
 import java.util.Collection;
+import java.util.List;
 
 public class SimpleDatabaseManager<E> implements DatabaseManager<E> {
 
@@ -78,33 +78,42 @@ public class SimpleDatabaseManager<E> implements DatabaseManager<E> {
   }
 
   @Override
-  public E getObject(int id) throws SQLException {
+  public E getObject(int taskId) throws SQLException {
     String query = getQuery(QueryMode.SELECT);
     Task task = null;
 
-    try (PreparedStatement ps = connection.prepareStatement(query)) {
-      ps.setInt(1, id);
+    PreparedStatement ps = connection.prepareStatement(query);
+    ps.setInt(1, taskId);
 
-      ResultSet resultSet = ps.executeQuery();
+    ResultSet resultSet = ps.executeQuery();
 
-      if (resultSet.next()) {
+    if (resultSet.next()) {
 
-        task = new Task(
-                resultSet.getInt("taskid"),
-                resultSet.getInt("workerid"),
-                resultSet.getString("name"),
-                resultSet.getString("description")
-        );
-        task.setTaskState(intToTaskState(resultSet.getInt("taskstate")));
-      }
+      task = new Task(
+              resultSet.getInt("taskid"),
+              resultSet.getInt("workerid"),
+              resultSet.getString("name"),
+              resultSet.getString("description")
+      );
+      task.setTaskState(intToTaskState(resultSet.getInt("taskstate")));
     }
 
     return (E) task;
   }
 
   @Override
-  public void deleteObject(int id) throws SQLException {
-    throw new SQLException("Not implemented yet");
+  public void deleteObject(int taskId) throws SQLException {
+    String query = getQuery(QueryMode.DELETE);
+
+    try (PreparedStatement ps = connection.prepareStatement(query)) {
+      ps.setInt(1, taskId);
+      ps.executeUpdate();
+    }
+  }
+
+  @Override
+  public E updateObject(int taskId, E object) throws SQLException {
+    return null;
   }
 
   @Override

test/hhn/temp/project/DatabaseBadCasesTest.java

@@ -6,6 +6,7 @@ import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
 
+import java.io.IOException;
 import java.sql.SQLException;
 
 import static org.junit.jupiter.api.Assertions.*;
@@ -27,7 +28,21 @@ public class DatabaseBadCasesTest {
   }
 
   @BeforeEach
-  public void setup() {
+  public void setup() throws SQLException, IOException {
     databaseManager = new SimpleDatabaseManager<>();
+    databaseManager.connect();
+    databaseManager.clearDatabase();
+  }
+
+  @Test
+  @DisplayName("Gets an object that may not be existent")
+  public void assertObjectShouldNotBeExistent() throws SQLException {
+    assertNull(databaseManager.getObject(999));
+  }
+
+  @Test
+  @DisplayName("Updates an object that does not exist")
+  public void assertUpdateNonExistentObject() throws SQLException {
+    assertNull(databaseManager.updateObject(123, new Task(1, 2, "", "")));
   }
 }

test/hhn/temp/project/DatabaseGoodCasesTest.java

@@ -2,7 +2,6 @@ package hhn.temp.project;
 
 import hhn.temp.project.provider.DatabaseManager;
 import hhn.temp.project.provider.SimpleDatabaseManager;
-import jdk.jshell.spi.ExecutionControl;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
@@ -17,19 +16,17 @@ import java.util.Collection;
 public class DatabaseGoodCasesTest {
 
   private DatabaseManager<Task> databaseManager;
-  private AssignmentManager manager;
 
   @BeforeEach
   public void setup() throws SQLException, IOException {
     databaseManager = new SimpleDatabaseManager<>();
     databaseManager.connect();
     databaseManager.clearDatabase();
-    manager = new AssignmentManager();
   }
 
   @Test
   @DisplayName("Assert that the TestClass could be inserted into the database")
-  public void assertGetTestClass() throws SQLException, IOException {
+  public void assertGetTestClass() throws SQLException {
 
     databaseManager.connect();
 
@@ -48,9 +45,26 @@ public class DatabaseGoodCasesTest {
     databaseManager.close();
   }
 
+  @Test
+  @DisplayName("Assert that an inserted and deleted task is not there anymore")
+  public void assertDeleteTest() throws SQLException {
+
+    databaseManager.connect();
+
+    Task task = new Task(9, 1, "hi", "hi");
+
+    databaseManager.saveObject(task);
+
+    databaseManager.deleteObject(9);
+
+    databaseManager.getObject(9);
+
+    databaseManager.close();
+  }
+
   @Test
   @DisplayName("Assert that a simple Task could be inserted into the database")
-  public void assertInsertTask() throws SQLException, IOException, ExecutionControl.NotImplementedException {
+  public void assertInsertTask() throws SQLException {
 
     Task testTask = new Task(1, 1, "Hello World", "Description");
 
@@ -60,8 +74,8 @@ public class DatabaseGoodCasesTest {
   }
 
   @Test
-  @DisplayName("Assert that simple Tasks could be inserted into the database")
-  public void assertInsertMultipleTasks() throws SQLException, IOException, ExecutionControl.NotImplementedException {
+  @DisplayName("Assert that multiple Tasks could be inserted into the database")
+  public void assertInsertMultipleTasks() throws SQLException {
 
     Task testTaskZero = new Task(1, 1, "Hello", "Description");
     Task testTaskOne = new Task(2, 2, "World", "Description");
@@ -76,4 +90,25 @@ public class DatabaseGoodCasesTest {
     databaseManager.saveObjects(tasks);
     databaseManager.close();
   }
+
+  @Test
+  @DisplayName("Assert insert object and update it")
+  public void assertInsertUpdateTask() throws SQLException {
+
+    int taskId = 1;
+
+    Task testTask = new Task(taskId, 1, "Hello World", "Description");
+    Task newTask = new Task(taskId, 1, "No World", "Description");
+
+    databaseManager.connect();
+    databaseManager.saveObject(testTask);
+    newTask = databaseManager.updateObject(testTask.getTaskId(), newTask);
+
+    assertNotNull(testTask);
+
+    assertNotEquals(testTask.getDescription(), newTask.getDescription());
+    assertEquals(testTask.getTaskId(), newTask.getTaskId());
+
+    databaseManager.close();
+  }
 }