style[DbWrapper]: add javadocs and split lines

src/main/java/edu/group5/app/model/wrapper/DbWrapper.java

@@ -15,6 +15,9 @@
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
+/**
+ * A class for wrapping the database.
+ */
 public class DbWrapper {
   protected Connection connection;
   private static final String CONNECTION_TYPE = "jdbc:h2:";
@@ -24,6 +27,11 @@ public class DbWrapper {
   private List<Object[]> donations;
   private Logger logger = Logger.getLogger(DbWrapper.class.getName());
 
+  /**
+   * The constructor, which constructs a String for connecting to the database.
+   * 
+   * @param test Whether to construct the connection String for testing (in-memory) or not.
+   */
   public DbWrapper(boolean test) {
     if (test) {
       this.connectionString = CONNECTION_TYPE + "mem:test;" + DB_SCRIPT + "test_init.sql'";
@@ -33,6 +41,11 @@ public DbWrapper(boolean test) {
     this.logger.info("connectionString constructed");
   }
 
+  /**
+   * Connects to the database, and returns the result, logging failures.
+   * 
+   * @return True if successful, false if not.
+   */
   public boolean connect() {
     try {
       this.connection = DriverManager.getConnection(this.connectionString);
@@ -49,7 +62,13 @@ public boolean connect() {
     }
   }
 
+  /**
+   * Disconnects the database connection, logging failures.
+   * 
+   * @return True if successful, false if not.
+   */
   public boolean disconnect() {
+    // We are not interested in whether it fails to close, as we check its closed status later.
     try{ this.connection.close(); } catch (Exception e) {};
     try {
       return this.connection.isClosed(); 
@@ -59,12 +78,25 @@ public boolean disconnect() {
     } 
   }
 
+  /**
+   * Closes queries and results.
+   * 
+   * @param results The ResultSet to close, can be null.
+   * @param ps The PreparedStatement to close, can be null.
+   */
   private void close(ResultSet results, PreparedStatement ps) {
+    // This method can take null arguments, so an exception is expected.
     try { results.close(); } catch (Exception e) {}
     try { ps.close(); } catch (Exception e) {}
     this.logger.info("results and ps closed");
   }
 
+  /**
+   * Gets all users from the database.
+   * 
+   * @return The users from the database returned as a List of Object arrays, where each Object
+   *      array represents a user and a row in the users table in the database.
+   */
   public List<Object[]> importUsers() {
     PreparedStatement ps = null;
     ResultSet results = null;
@@ -93,7 +125,17 @@ public List<Object[]> importUsers() {
     return this.users;
   }
 
-  public int exportUsers(List<Object[]> data) {
+  /**
+   * Puts new users into the database.
+   * 
+   * @param data The new users to put into the database. Each Object array in the List is a new
+   *      user to add as a row.
+   * @return The number of rows affected in the transaction.
+   * @throws IllegalArgumentException This exception is thrown when data is null, its rows are not
+   *      of length 6, any of the rows are null, any of the rows are duplicates or existing rows in
+   *      the database, or any of the values in the rows can't be cast to the correct data-types.
+   */
+  public int exportUsers(List<Object[]> data) throws IllegalArgumentException {
     this.importUsers();
 
     if (data == null) {
@@ -102,12 +144,14 @@ public int exportUsers(List<Object[]> data) {
     if (data.isEmpty()) {
       return 0;
     }
+    // TODO: change to check length for every row.
     if (data.get(0).length != 6) {
       throw new IllegalArgumentException("data's arrays must have a length of 6");
     }
     if (data.stream().anyMatch(i -> Arrays.asList(i).contains(null))) {
       throw new IllegalArgumentException("One or more rows in data contains null values");
     }
+    // TODO: change how existing rows are checked.
     if (this.users.size() > 0) {
       if ((int) data.getLast()[0] <= (int) this.users.getLast()[0]) {
         throw new IllegalArgumentException("data can't contain existing rows");
@@ -123,7 +167,13 @@ public int exportUsers(List<Object[]> data) {
     int rowsAffected = 0;
     try {
       ps = this.connection.prepareStatement(
-          "INSERT INTO users (user_id, role, first_name, last_name, email, password_hash) VALUES (?, ?, ?, ?, ?, ?)");
+        """
+          INSERT INTO users
+            (user_id, role, first_name, last_name, email, password_hash)
+          VALUES 
+            (?, ?, ?, ?, ?, ?)
+        """
+      );
       for (Object[] row : data) {
         try {
           ps.setInt(1, (int) row[0]);
@@ -144,18 +194,29 @@ public int exportUsers(List<Object[]> data) {
     return rowsAffected;
   }
 
+  /**
+   * Imports all donations.
+   * 
+   * @return A List of Object arrays for each donation in the database.
+   */
   public List<Object[]> fetchAllDonations() {
     return this.importDonations(0, true);
   }
 
+  /**
+   * Imports the donations of a specific user based on a given user_id.
+   * 
+   * @param user_id The id of the user to get the donations of.
+   * @return A List of Object arrays for each donation in the database.
+   */
   public List<Object[]> importDonations(int user_id) {
     return this.importDonations(user_id, false);
   }
 
   private List<Object[]> importDonations(int user_id, boolean all) {
     PreparedStatement ps = null;
     ResultSet results = null;
-    try{
+    try {
       if (all) {
         ps = this.connection.prepareStatement("SELECT * FROM donations");
       } else {
@@ -185,7 +246,17 @@ private List<Object[]> importDonations(int user_id, boolean all) {
     return this.donations;
   }
 
-  public int exportDonations(List<Object[]> data) {
+  /**
+   * Puts new donations into the database.
+   * 
+   * @param data The new donation to put into the database. Each Object array in the List is a new
+   *      donations to add as a row.
+   * @return The number of rows affected in the transaction.
+   * @throws IllegalArgumentException This exception is thrown when data is null, its rows are not
+   *      of length 6, any of the rows are null, any of the rows are duplicates or existing rows in
+   *      the database, or any of the values in the rows can't be cast to the correct data-types.
+   */
+  public int exportDonations(List<Object[]> data) throws IllegalArgumentException {
     this.fetchAllDonations();
 
     if (data == null) {
@@ -212,7 +283,13 @@ public int exportDonations(List<Object[]> data) {
     int rowsAffected = 0;
     try {
       ps = this.connection.prepareStatement(
-          "INSERT INTO donations (donation_id, user_id, organization_id, amount, dating, payment_method) VALUES (?, (SELECT user_id FROM users WHERE user_id = ?), ?, ?, ?, ?)");
+        """
+          INSERT INTO donations
+            (donation_id, user_id, organization_id, amount, dating, payment_method)
+          VALUES
+            (?, (SELECT user_id FROM users WHERE user_id = ?), ?, ?, ?, ?)
+        """
+      );
       for (Object[] row : data) {
         try {
           for (int i = 0; i < 3; i++) {