How to handle compound key with relationship in JPA2 and Spring Data JPA? -

i have problem handle mapping object relationship mysql tables. have 2 tables shown below:

device ----------- deviceid pk devicename  apkinfo -------- id pk packagename appname deviceid fk 

and here classes:

@entity @table(name="device") public class device implements serializable {     @column    @id    private string deviceid;     @column    private string devicename;     //getters , setters  }   @entity @table(name="apkinfos") public class apkinfo implements serializable {     @column    @id    @generatedvalue(strategy=generationtype.auto)    private int id;     @column    @id    private string packagename;     @column    private string appname;     @column    @temporal(temporaltype.timstamp)    private date installdate;     @manytoone    @joincolumn(name="deviceid" referencedcolumnname="deviceid")    private device device;     //getters , setters  } 

this works me, want use compound key, deviceid , packagename, in apkinfos table.

@entity @table(name="apkinfos") public class apkinfo implements serializable {     @colum(instable=false, updatable=false)    @id    private string deviceid;     @column    private string packagename;     @column    private string appname;     @manytoone    @joincolumn(name="deviceid" referencedcolumnname="deviceid")    private device device;     //getters , setters  } 

but when tried save entity using spring data jpa repository, got error:

org.springframework.dao.invalidaccessapiusageexception: class must not null, nested exception java.lang.illegalargumentexception: class must not null

apkinfo apkinfo = new apkinfo(); apkinfo.setdeviceid("1234"); apkinfo.setpackagename("aaa"); apkinfo.setappname("myapp"); apkinfo.setinstalldate(new date()); apkinfo.setdevice(new device("1234"));  repository.save(apkinfo); 

and device has deviceid '1234' exists in device table.

i created separate primary key class added @idclass in apkinfo class. works fine now, thanks. going have @ embeddedid more later.

i added @idclass @ entity class , @id packagename property. made insert, update false one-to-many column.

@entity @table(name="apkinfos") @idclass(apkinfo.class) public class apkinfo implements serializable {     @column @id private string deviceid;    @column @id private string packagename;     @manytoone    @joincolumn(name="deviceid" referencedcolumnname="deviceid", insetable=false, updatable=false)    private device device;     //getters , setters missing } 

primary key class has setters , overrides equals , hascode methods.

public class apkinfo implements serializable {     private string deviceid;    private string packagename;      public apkinfo(){}    public apkinfo (string deviceid, string packagename){        this.deviceid = deviceid;        this.packagename = packagename;    }     public string getdeviceid(){       return this.deviceid;    }     public string getpackagename(){       return this.packagename;    }     @override    public boolean equals(object obj){       return (obj!=null &&                obj instanceof apkinfopk &&                deviceid.equals(((apkinfopk)obj).getdeviceid())  &&                packagenames.equals(((apkinfopk)obj).getpackagename()) );    }     @override    public int hashcode(){       super.hashcode();    } }