How to check if a particular database in mysql already exists using java

show databases like 'students'

If you get a row back, it exists.

You're doing it back to front. The correct technique is to try to create it and catch the exception. The way you want to do it is subject to timing-window problems: it wasn't there when you tested, but it was there when you tried to create it. And you still have to catch the exception anyway.

You can get that info from a JDBC Connection using DatabaseMetaData#getCatalogs, here is an example of getting the Catalogs, aka Database names

// Connection connection = <your java.sql.Connection>
ResultSet resultSet = connection.getMetaData().getCatalogs();

//iterate each catalog in the ResultSet
while (resultSet.next()) {
  // Get the database name, which is at position 1
  String databaseName = resultSet.getString(1);
}
resultSet.close();

In newer versions of MySQL (5 and above) run this query:

SELECT COUNT(*)
FROM information_schema.tables 
WHERE table_schema = '[database name]' 
AND table_name = '[table name]';

If the result is 1 it exists.

In Java JDBC that would look something like this:

// Create connection and statement
String query = "SELECT COUNT(*) FROM information_schema.tables WHERE table_schema'[database name]' AND table_name = '[table name]'";
ResultSet rs = stmt.executeQuery(query);                  
rs.next();
boolean exists = rs.getInt("COUNT(*)") > 0;
// Close connection, statement, and result set.
return exists;