First review changes++

First review changes++

data-mapper/src/main/java/com/iluwatar/datamapper/StudentDataMapperImpl.java

@@ -0,0 +1,102 @@
+/**
+ * The MIT License Copyright (c) 2016 Amit Dixit
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
+ * associated documentation files (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge, publish, distribute,
+ * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all copies or
+ * substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
+ * NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+ * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.iluwatar.datamapper;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Optional;
+
+public final class StudentDataMapperImpl implements StudentDataMapper {
+
+  /* Note: Normally this would be in the form of an actual database */
+  private List<Student> students = new ArrayList<>();
+
+  @Override
+  public Optional<Student> find(int studentId) {
+
+    /* Compare with existing students */
+    for (final Student student : this.getStudents()) {
+
+      /* Check if student is found */
+      if (student.getStudentId() == studentId) {
+
+        return Optional.of(student);
+      }
+    }
+
+    /* Return empty value */
+    return Optional.empty();
+  }
+
+  @Override
+  public void update(Student studentToBeUpdated) throws DataMapperException {
+
+
+    /* Check with existing students */
+    if (this.getStudents().contains(studentToBeUpdated)) {
+
+      /* Get the index of student in list */
+      final int index = this.getStudents().indexOf(studentToBeUpdated);
+
+      /* Update the student in list */
+      this.getStudents().set(index, studentToBeUpdated);
+
+    } else {
+
+      /* Throw user error after wrapping in a runtime exception */
+      throw new DataMapperException("Student [" + studentToBeUpdated.getName() + "] is not found");
+    }
+  }
+
+  @Override
+  public void insert(Student studentToBeInserted) throws DataMapperException {
+
+    /* Check with existing students */
+    if (!this.getStudents().contains(studentToBeInserted)) {
+
+      /* Add student in list */
+      this.getStudents().add(studentToBeInserted);
+
+    } else {
+
+      /* Throw user error after wrapping in a runtime exception */
+      throw new DataMapperException("Student already [" + studentToBeInserted.getName() + "] exists");
+    }
+  }
+
+  @Override
+  public void delete(Student studentToBeDeleted) throws DataMapperException {
+
+    /* Check with existing students */
+    if (this.getStudents().contains(studentToBeDeleted)) {
+
+      /* Delete the student from list */
+      this.getStudents().remove(studentToBeDeleted);
+
+    } else {
+
+      /* Throw user error after wrapping in a runtime exception */
+      throw new DataMapperException("Student [" + studentToBeDeleted.getName() + "] is not found");
+    }
+  }
+
+  public List<Student> getStudents() {
+    return this.students;
+  }
+}