Added more checks for failed database connections.

Should prevent unnecessary null pointer exceptions if anything goes wrong.

Signed-off-by: Jeffrey Han <itdelatrisu@gmail.com>

src/itdelatrisu/opsu/db/DBController.java

@@ -20,6 +20,10 @@ package itdelatrisu.opsu.db;
 
 import itdelatrisu.opsu.ErrorHandler;
 
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.SQLException;
+
 /**
  * Database controller.
  */
@@ -50,4 +54,19 @@ public class DBController {
 		OsuDB.closeConnection();
 		ScoreDB.closeConnection();
 	}
+
+	/**
+	 * Establishes a connection to the database given by the path string.
+	 * @param path the database path
+	 * @return the Connection, or null if a connection could not be established
+	 */
+	public static Connection createConnection(String path) {
+		try {
+			return DriverManager.getConnection(String.format("jdbc:sqlite:%s", path));
+		} catch (SQLException e) {
+			// if the error message is "out of memory", it probably means no database file is found
+			ErrorHandler.error(String.format("Could not connect to database: '%s'.", path), e, true);
+			return null;
+		}
+	}
 }

src/itdelatrisu/opsu/db/OsuDB.java

@@ -25,7 +25,6 @@ import itdelatrisu.opsu.OsuParser;
 
 import java.io.File;
 import java.sql.Connection;
-import java.sql.DriverManager;
 import java.sql.PreparedStatement;
 import java.sql.ResultSet;
 import java.sql.SQLException;
@@ -58,12 +57,9 @@ public class OsuDB {
 	 */
 	public static void init() {
 		// create a database connection
-		try {
+		connection = DBController.createConnection(Options.OSU_DB.getPath());
-			connection = DriverManager.getConnection(String.format("jdbc:sqlite:%s", Options.OSU_DB.getPath()));
+		if (connection == null)
-		} catch (SQLException e) {
+			return;
-			// if the error message is "out of memory", it probably means no database file is found
-			ErrorHandler.error("Could not connect to beatmap database.", e, true);
-		}
 
 		// create the database
 		createDatabase();
@@ -124,6 +120,9 @@ public class OsuDB {
 	 * from the current version, then updates the version field.
 	 */
 	private static void checkVersion() {
+		if (connection == null)
+			return;
+
 		try (Statement stmt = connection.createStatement()) {
 			// get the stored version
 			String sql = "SELECT value FROM info WHERE key = 'version'";
@@ -149,6 +148,9 @@ public class OsuDB {
 	 * Clears the database.
 	 */
 	public static void clearDatabase() {
+		if (connection == null)
+			return;
+
 		// drop the table, then recreate it
 		try (Statement stmt = connection.createStatement()) {
 			String sql = "DROP TABLE beatmaps";
@@ -164,6 +166,9 @@ public class OsuDB {
 	 * @param osu the OsuFile object
 	 */
 	public static void insert(OsuFile osu) {
+		if (connection == null)
+			return;
+
 		try {
 			setStatementFields(insertStmt, osu);
 			insertStmt.executeUpdate();
@@ -177,6 +182,9 @@ public class OsuDB {
 	 * @param batch a list of OsuFile objects
 	 */
 	public static void insert(List<OsuFile> batch) {
+		if (connection == null)
+			return;
+
 		try (Statement stmt = connection.createStatement()) {
 			// turn off auto-commit mode
 			boolean autoCommit = connection.getAutoCommit();
@@ -258,8 +266,12 @@ public class OsuDB {
 	 * Returns an OsuFile from the database, or null if any error occurred.
 	 * @param dir the directory
 	 * @param file the file
+	 * @return the OsuFile with all fields filled, or null if any error occurred
 	 */
 	public static OsuFile getOsuFile(File dir, File file) {
+		if (connection == null)
+			return null;
+
 		try {
 			OsuFile osu = new OsuFile(file);
 			selectStmt.setString(1, dir.getName());
@@ -316,6 +328,9 @@ public class OsuDB {
 	 * null if any error occurred.
 	 */
 	public static Map<String, Long> getLastModifiedMap() {
+		if (connection == null)
+			return null;
+
 		try {
 			Map<String, Long> map = new HashMap<String, Long>();
 			ResultSet rs = lastModStmt.executeQuery();
@@ -338,6 +353,9 @@ public class OsuDB {
 	 * @param file the file
 	 */
 	public static void delete(String dir, String file) {
+		if (connection == null)
+			return;
+
 		try {
 			deleteMapStmt.setString(1, dir);
 			deleteMapStmt.setString(2, file);
@@ -352,6 +370,9 @@ public class OsuDB {
 	 * @param dir the directory
 	 */
 	public static void delete(String dir) {
+		if (connection == null)
+			return;
+
 		try {
 			deleteGroupStmt.setString(1, dir);
 			deleteGroupStmt.executeUpdate();
@@ -364,17 +385,19 @@ public class OsuDB {
 	 * Closes the connection to the database.
 	 */
 	public static void closeConnection() {
-		if (connection != null) {
+		if (connection == null)
-			try {
+			return;
-				insertStmt.close();
+
-				lastModStmt.close();
+		try {
-				selectStmt.close();
+			insertStmt.close();
-				deleteMapStmt.close();
+			lastModStmt.close();
-				deleteGroupStmt.close();
+			selectStmt.close();
-				connection.close();
+			deleteMapStmt.close();
-			} catch (SQLException e) {
+			deleteGroupStmt.close();
-				ErrorHandler.error("Failed to close beatmap database.", e, true);
+			connection.close();
-			}
+			connection = null;
+		} catch (SQLException e) {
+			ErrorHandler.error("Failed to close beatmap database.", e, true);
 		}
 	}
 }

src/itdelatrisu/opsu/db/ScoreDB.java

@@ -24,7 +24,6 @@ import itdelatrisu.opsu.OsuFile;
 import itdelatrisu.opsu.ScoreData;
 
 import java.sql.Connection;
-import java.sql.DriverManager;
 import java.sql.PreparedStatement;
 import java.sql.ResultSet;
 import java.sql.SQLException;
@@ -60,12 +59,9 @@ public class ScoreDB {
 	 */
 	public static void init() {
 		// create a database connection
-		try {
+		connection = DBController.createConnection(Options.SCORE_DB.getPath());
-			connection = DriverManager.getConnection(String.format("jdbc:sqlite:%s", Options.SCORE_DB.getPath()));
+		if (connection == null)
-		} catch (SQLException e) {
+			return;
-			// if the error message is "out of memory", it probably means no database file is found
-			ErrorHandler.error("Could not connect to score database.", e, true);
-		}
 
 		// create the database
 		createDatabase();
@@ -127,6 +123,9 @@ public class ScoreDB {
 	 * @param data the GameData object
 	 */
 	public static void addScore(ScoreData data) {
+		if (connection == null)
+			return;
+
 		try {
 			setStatementFields(insertStmt, data);
 			insertStmt.executeUpdate();
@@ -140,6 +139,9 @@ public class ScoreDB {
 	 * @param data the score to delete
 	 */
 	public static void deleteScore(ScoreData data) {
+		if (connection == null)
+			return;
+
 		try {
 			setStatementFields(deleteScoreStmt, data);
 			deleteScoreStmt.executeUpdate();
@@ -153,6 +155,9 @@ public class ScoreDB {
 	 * @param osu the OsuFile object
 	 */
 	public static void deleteScore(OsuFile osu) {
+		if (connection == null)
+			return;
+
 		try {
 			deleteSongStmt.setInt(1, osu.beatmapID);
 			deleteSongStmt.setString(2, osu.title);
@@ -195,9 +200,12 @@ public class ScoreDB {
 	/**
 	 * Retrieves the game scores for an OsuFile map.
 	 * @param osu the OsuFile
-	 * @return all scores for the beatmap
+	 * @return all scores for the beatmap, or null if any error occurred
 	 */
 	public static ScoreData[] getMapScores(OsuFile osu) {
+		if (connection == null)
+			return null;
+
 		List<ScoreData> list = new ArrayList<ScoreData>();
 		try {
 			selectMapStmt.setInt(1, osu.beatmapID);
@@ -221,9 +229,13 @@ public class ScoreDB {
 	/**
 	 * Retrieves the game scores for an OsuFile map set.
 	 * @param osu the OsuFile
-	 * @return all scores for the beatmap set (Version, ScoreData[])
+	 * @return all scores for the beatmap set (Version, ScoreData[]),
+	 *         or null if any error occurred
 	 */
 	public static Map<String, ScoreData[]> getMapSetScores(OsuFile osu) {
+		if (connection == null)
+			return null;
+
 		Map<String, ScoreData[]> map = new HashMap<String, ScoreData[]>();
 		try {
 			selectMapSetStmt.setInt(1, osu.beatmapSetID);
@@ -267,15 +279,17 @@ public class ScoreDB {
 	 * Closes the connection to the database.
 	 */
 	public static void closeConnection() {
-		if (connection != null) {
+		if (connection == null)
-			try {
+			return;
-				insertStmt.close();
+
-				selectMapStmt.close();
+		try {
-				selectMapSetStmt.close();
+			insertStmt.close();
-				connection.close();
+			selectMapStmt.close();
-			} catch (SQLException e) {
+			selectMapSetStmt.close();
-				ErrorHandler.error("Failed to close score database.", e, true);
+			connection.close();
-			}
+			connection = null;
+		} catch (SQLException e) {
+			ErrorHandler.error("Failed to close score database.", e, true);
 		}
 	}
 }