swing - JTable doesn't show all over in JFrame in java -

i have jtable add jpanel. add jpanel jframe called frame. frame show table when maximize window jpanel still remains small size. want show jpanel on frame when maximize frame. here code:

import java.awt.borderlayout; import java.sql.connection; import java.sql.drivermanager; import java.sql.resultset; import java.sql.resultsetmetadata; import java.sql.statement; import java.util.vector;  import javax.swing.jframe; import javax.swing.jpanel; import javax.swing.jscrollpane; import javax.swing.jtable;  @suppresswarnings("serial") public class testclass extends jpanel {     public testclass()     {         vector columnnames = new vector();         vector data = new vector();               int columns =3;              //  column names              columnnames.addelement("id");             columnnames.addelement("name");             columnnames.addelement("age");              //  row data              vector row = new vector(columns);             row.addelement("1");             row.addelement("moshi");             row.addelement("22");              data.addelement( row );             //  create table database data          jtable table = new jtable(data, columnnames)         {             public class getcolumnclass(int column)             {                 (int row = 0; row < getrowcount(); row++)                 {                     object o = getvalueat(row, column);                      if (o != null)                     {                         return o.getclass();                     }                 }                  return object.class;             }         };          jscrollpane scrollpane = new jscrollpane( table );         add(scrollpane);      }      public static void main(string[] args)     {         testclass testclass  = new testclass(); //**jpanel**         jframe frame = new jframe();         frame.setsize(500, 600);         frame.getcontentpane().add(testclass); //**add jpanel frame**         frame.setvisible(true);     } } 

use layout manager sizes components according available size rather jpanel's default flowlayout uses components preferred size, e.g.

setlayout(new gridlayout());