You can use generateUniqueID OOTB activity

but if i use generateuniqueID its not sequence, id random sir.. i want get sequence in postgres 

and if i use 2 application (pega and eclipse) but in 1 database, how can i generate this ID?

I think you can create a function for generating sequence ID using java Code.

No u can create a function and write the java code in it to generate sequenceID and use that in the activity.

if i create function, how can i connect it between sequence in postgres and java code?

you can make use of pega OOTB GenerateID activity which is used by pega to generate pyID in case of flow. This automatically makes entry in pega DB table "PC_DATA_UNIQUEID" and OOTB generate no in sequence.

if i use pyId, how to synch with postgres? whether the sequence in postgres will be updated automatically?

and if in one case there are two lists how can i generate id, if i use pyId?

thank you

use pzGenerateUniqueID function to generate a unique id based on the prefix passed to this utility.

Ex: If prefix is given as "SPEC", id is generated as "SPEC-1"

but if i use 2 application?? and if in database postgres sequence is 7. it will continuesly to 8?? 

But if you use two Applications which are inserting in the same Database records it would be not a good idea to handel this on application side.

In my point of view its better to handel this on DB side. For Postgres there is a function (SERIAL) to auto increment the id. 
Example: First insert id = 1, Second insert id = 2 and so on.

Example Table creation:

CREATE TABLE COMPANY(
   ID  SERIAL PRIMARY KEY,
   NAME           TEXT      NOT NULL,
   AGE            INT       NOT NULL,
   ADDRESS        CHAR(50),
   SALARY         REAL
);

More Information you can find here:
https://www.tutorialspoint.com/postgresql/postgresql_using_autoincrement.htm