Replace EventStorage.java

src/main/java/inf226/inchat/EventStorage.java

 package inf226.inchat;
 
-import java.sql.Connection;
-import java.sql.ResultSet;
-import java.sql.SQLException;
-import java.sql.Statement;
+import java.sql.*;
 import java.time.Instant;
 import java.util.UUID;
 import java.util.function.Consumer;
@@ -18,9 +15,8 @@ public final class EventStorage
     implements Storage<Channel.Event,SQLException> {
     
     private final Connection connection;
-    
-    public EventStorage(Connection connection) 
-      throws SQLException {
+
+    public EventStorage(Connection connection) throws SQLException {
         this.connection = connection;
         connection.createStatement()
                 .executeUpdate("CREATE TABLE IF NOT EXISTS Event (id TEXT PRIMARY KEY, version TEXT, channel TEXT, type INTEGER, time TEXT, FOREIGN KEY(channel) REFERENCES Channel(id) ON DELETE CASCADE)");
@@ -31,8 +27,7 @@ public final class EventStorage
     }
     
     @Override
-    public Stored<Channel.Event> save(Channel.Event event)
-      throws SQLException {
+    public Stored<Channel.Event> save(Channel.Event event) throws SQLException {
         
         final Stored<Channel.Event> stored = new Stored<Channel.Event>(event);
         
@@ -58,11 +53,8 @@ public final class EventStorage
     }
     
     @Override
-    public synchronized Stored<Channel.Event> update(Stored<Channel.Event> event,
-                                            Channel.Event new_event)
-        throws UpdatedException,
-            DeletedException,
-            SQLException {
+    public synchronized Stored<Channel.Event> update(Stored<Channel.Event> event, Channel.Event new_event)
+            throws UpdatedException, DeletedException, SQLException {
     final Stored<Channel.Event> current = get(event.identity);
     final Stored<Channel.Event> updated = current.newVersion(new_event);
     if(current.version.equals(event.version)) {
@@ -92,24 +84,23 @@ public final class EventStorage
    
     @Override
     public synchronized void delete(Stored<Channel.Event> event)
-       throws UpdatedException,
-              DeletedException,
-              SQLException {
+            throws UpdatedException, DeletedException, SQLException {
+
         final Stored<Channel.Event> current = get(event.identity);
         if(current.version.equals(event.version)) {
-        String sql =  "DELETE FROM Event WHERE id ='" + event.identity + "'";
-        connection.createStatement().executeUpdate(sql);
+            String sql =  "DELETE FROM Event WHERE id ='" + event.identity + "'";
+           connection.createStatement().executeUpdate(sql);
         } else {
         throw new UpdatedException(current);
         }
     }
     @Override
-    public Stored<Channel.Event> get(UUID id)
-      throws DeletedException,
-             SQLException {
-        final String sql = "SELECT version,channel,time,type FROM Event WHERE id = '" + id.toString() + "'";
-        final Statement statement = connection.createStatement();
-        final ResultSet rs = statement.executeQuery(sql);
+    public Stored<Channel.Event> get(UUID id) throws DeletedException, SQLException {
+        final String sqlQuery = "SELECT version,channel,time,type FROM Event WHERE id = ? ";
+        final String sql = id.toString();
+        final PreparedStatement statement = connection.prepareStatement(sqlQuery);
+        statement.setString(1, sql);
+        final ResultSet rs = statement.executeQuery();
 
         if(rs.next()) {
             final UUID version = UUID.fromString(rs.getString("version"));
@@ -120,19 +111,25 @@ public final class EventStorage
             final Instant time = 
                 Instant.parse(rs.getString("time"));
             
-            final Statement mstatement = connection.createStatement();
+            final PreparedStatement mstatement;
             switch(type) {
                 case message:
-                    final String msql = "SELECT sender,content FROM Message WHERE id = '" + id.toString() + "'";
-                    final ResultSet mrs = mstatement.executeQuery(msql);
+                    final String msqlQuery = "SELECT sender,content FROM Message WHERE id = ? ";
+                    final String msql = id.toString();
+                    mstatement = connection.prepareStatement(msqlQuery);
+                    mstatement.setString(1, msql);
+                    final ResultSet mrs = mstatement.executeQuery();
                     mrs.next();
                     return new Stored<Channel.Event>(
                             Channel.Event.createMessageEvent(channel,time,mrs.getString("sender"),mrs.getString("content")),
                             id,
                             version);
                 case join:
-                    final String asql = "SELECT sender FROM Joined WHERE id = '" + id.toString() + "'";
-                    final ResultSet ars = mstatement.executeQuery(asql);
+                    final String asqlQuery = "SELECT sender FROM Joined WHERE id = ? ";
+                    final String asql = id.toString();
+                    mstatement = connection.prepareStatement(asqlQuery);
+                    mstatement.setString(1, asql);
+                    final ResultSet ars = mstatement.executeQuery();
                     ars.next();
                     return new Stored<Channel.Event>(
                             Channel.Event.createJoinEvent(channel,time,ars.getString("sender")),