Have a look and see what is using up all these processes (by checking the v$process and v$session tables). That will let you know what the culrpit is. It could be that your database is not configured to allow enough processes, in which case increase that with the PROCESSES initialization parameter.
This means that all of 150 configured connection are in use .for resolving this you can increase the maxconnection to a high number .But I think their is a problem in your java application and the problem is application is not dropping database connection i.e. connection are not closed in jsp/java files. check for connection.close();