Java - MySQL - Create connection error

Question

I don't know why but this line gives me an error. I'm first making a few private strings, host, port, database, user and password. Then I'm setting those strings in the constructor.

Connection conn = DriverManager.getConnection("jdbc:mysql://" + host + ":" + port + "/" + database + "?user=" + user + "&password=" + password);

This is the error message that I get:

com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Cannot load connection class because of underlying exception: 'java.lang.Number FormatException: For input string: "null"'.

What did I do wrong here?

Eran · Accepted Answer · 2014-07-23 14:35:50Z

3

The most likely cause is that one of your parameters is null. Probably port, since an attempt is made to convert it to a number.

Unless you are using a non default port (the default being 3306), you can just omit the port :

Connection conn = DriverManager.getConnection("jdbc:mysql://" + host + "/" + database + "?user=" + user + "&password=" + password);

answered Jul 23, 2014 at 14:35

Eran

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Azar · Accepted Answer · 2014-07-23 14:41:36Z

1

My guess, without seeing more code, is that port is null.

When you pass the string to the getConnection() method, it tries to parse out the port as a number. The when you concatenate a null value to a String, it appends 'null'. Now your string looks like jdbc:mysql://examplehost:null. Thus the java.lang.Number FormatException: For input string: "null".

edited Jul 23, 2014 at 14:41

answered Jul 23, 2014 at 14:35

Azar

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Vimal Bera · Accepted Answer · 2014-07-23 14:36:07Z

0

Its preety much clear from the Exception. Its because your port is null and throws exception while tried to parse into Number.

answered Jul 23, 2014 at 14:36

Vimal Bera

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