java - Overwrite existing file -

i want overwrite 2 files. both files store information in memory database (hsqldb): db.data , db.script

my following code should this:

public class dbreset {     public path db_data = paths.get("db_sep/db_backup/db.data");     public path db_script = paths.get("db_sep/db_backup/db.script");     public path dest_data = paths.get("db_sep/db.data");     public path dest_script = paths.get("db_sep/db.script");      public void discard() throws ioexception {         files.copy(this.db_data, this.dest_data, standardcopyoption.replace_existing);         files.copy(this.db_script, this.dest_script, standardcopyoption.replace_existing);     } } 

however if use

public class anotherclass {     new dbreset.discard();     // db     new dbreset.discard();     // other db } 

the second discard() not overwrites files.

i use discard() reset database original state. please don't ask / tell me there other ways reset database, actual problem why not overwrite files.

sadly shutdown not work.

public void discard() throws ioexception, sqlexception {     connection c = dbconnectfactory.getdatasource.getconnection();     preparedstatement ps = c.preparedstatement("shutdown");      ps.executeupdate();     ps.close();     c.close();      files.copy(this.db_data, this.dest_data, standardcopyoption.replace_existing);     files.copy(this.db_script, this.dest_script, standardcopyoption.replace_existing); } 

throws @ first line of connection c = dbconnectfactory.getdatasource.getconnection(); java.sql.exception: error in script file line: 1 unknown token: ... lots of unknown sources.

also tested in runquery(string query) - opens connection , executes given query via preparedstatement - force shutdown, throws same error above, should connection @ getconnection().

what want is:

1. restore original db instance.
2. do stuff db, select, insert , assertions. test stuff against database.
3. restore original db instance.
4. do other tests against database.

ps: i'm using hsqldb in file mode.