java.lang.OutOfMemoryError: Java heap space

Question

i get this error when calling a mysql Prepared Statement every 30 seconds this is the code which is been called:

public static int getUserConnectedatId(Connection conn, int i) throws SQLException {
    pstmt = conn.prepareStatement("SELECT UserId from connection where ConnectionId ='" + i + "'");
    ResultSet rs = pstmt.executeQuery();
    int id = -1;
    if (rs.next()) {
        id = rs.getInt(1);
    }
    pstmt = null;
    rs = null;
    return id;
}

not sure what the problem is :s thanks in advanced.

Answer 1

You need to close all the resources you create - prepared statement, resultset, etc.

Answer 2

check your memory.

linux command: free

Answer 3

Because you are running out of memory as your ResultSet is occupyng more memory compared to default memory.

Solution: At the time of starting the application use this argument java or javaw -Xms 25M -Xmx 1024M

Answer 4

I will add some lines to my previous answer

Force yor Garbage collection by making the main thread sleep for 2s.

Answer 5

Why not make the query parameterized and simply change the connection ID? That's how prepared statements were intended to be used. That way you only compile the statement once, and re-use the compiled query plan (or whatever your DB compiles your query into).