swing - Doesn't show scroll in JScrollPane with JTable after Upgrade Java 7 to Java 8 -

i've upgrade project java 8. after running application, scroll jscrollpane doesn't show. same piece of code works in java 7 , ok.

public static void main(string[] a){     jpanel contentpane = new jpanel();     contentpane.setbackground(color.white);     contentpane.setborder(new emptyborder(0, 0, 0, 0));     contentpane.setlayout(new javax.swing.boxlayout(contentpane, javax.swing.boxlayout.y_axis));      jpanel aggregates = new jpanel("aggregates", new insets(40, 0, 0, 0));     gridbagconstraints gbc_aggregates = new gridbagconstraints(0, 2, 1, 1, 0.0, 0.0, gridbagconstraints.west, 1, new insets(10, 10, 10, 10), 0, 0);     gbl_panel.setconstraints(aggregates, gbc_aggregates);      gridbaglayout gbl_agregats = new gridbaglayout();        addparameterslayout(gbl_agregats, new int[]{0,0,0}, new int[]{0, 0},new double[]{ 0.0, 0.0, double.min_value}, new double[]{0.0, double.min_value} );     aggregates.setlayout(gbl_agregats);      jtable table = new jtable(new mytablemodel(null));     table.setpreferredsize(new dimension(850, const.rowheight));      jscrollpane scrollpane = new jscrollpane(table);     table.setpreferredscrollableviewportsize(new dimension(850, 10 *const.rowheight));     gridbagconstraints gbc_scrollpane= new gridbagconstraints(0, 1, 3, 1, 0.0, 0.0, gridbagconstraints.west, 1, new insets(5, 5, 20, 5), 0, 0);     gbl_agregats.setconstraints(scrollpane, gbc_scrollpane);     aggregates.add(scrollpane);      jpanel main_panel = new jpanel();     main_panel.add(aggregates);       jscrollpane scrpane = new jscrollpane(main_panel);     scrpane.getverticalscrollbar().setunitincrement(16);     scrpane.setborder(borderfactory.createemptyborder());     scrpane.getinsets().set(0, 0, 0, 0);     contentpane.add(scrpane);     setcontentpane(contentpane);     }  public static void addparameterslayout(gridbaglayout gbl, int[] columnwidths, int[] rowheights, double[] columnweights, double[] rowweights) {     gbl.columnwidths = columnwidths;     gbl.rowheights = rowheights;     gbl.columnweights = columnweights;     gbl.rowweights = rowweights; } 

question: changed in java 8 ? why same scroll looks ok in older java version ?

edited:

maybe i'm not specific. when compile project see (just bar):

i can scroll table because it's working, it's invisible (i see bar).

          import java.awt.color;           import java.awt.dimension;           import java.awt.gridbagconstraints;           import java.awt.gridbaglayout;           import java.awt.insets;           import java.awt.layoutmanager;           import javax.swing.borderfactory;           import javax.swing.jpanel;           import javax.swing.jscrollpane;           import javax.swing.jtab           import javax.swing.border.emptyborder;              public class source8 {               public static void main(string[] a){           jpanel contentpane = new jpanel();           contentpane.setbackground(color.white);           contentpane.setborder(new emptyborder(0, 0, 0, 0));           contentpane.setlayout(new javax.swing.boxlayout(contentpane,              javax.swing.boxlayout.y_axis));            jpanel aggregates = new jpanel((layoutmanager) new insets(40, 0,0,           0));           gridbagconstraints gbc_aggregates = new gridbagconstraints(0, 2,            1, 1, 0.0, 0.0, gridbagconstraints.west, 1, new insets(10, 10, 10,            10), 0, 0);           gridbaglayout gbl_panel = new gridbaglayout();                gbl_panel.setconstraints(aggregates, gbc_aggregates);            gridbaglayout gbl_agregats = new gridbaglayout();              addparameterslayout(gbl_agregats, new int[]{0,0,0}, new int[]{0,            0},new double[]{ 0.0, 0.0, double.min_value}, new double[]{0.0,           double.min_value} );           aggregates.setlayout(gbl_agregats);            jtable table = new jtable(new mytablemodel(null));           table.setpreferredsize(new dimension(850, const.rowheight));            jscrollpane scrollpane = new jscrollpane(table);           table.setpreferredscrollableviewportsize(new dimension(850, 10            *const.rowheight));           gridbagconstraints gbc_scrollpane= new gridbagconstraints(0, 1, 3,           1, 0.0, 0.0, gridbagconstraints.west, 1, new insets(5, 5, 20, 5),           0, 0);           gbl_agregats.setconstraints(scrollpane, gbc_scrollpane);           aggregates.add(scrollpane);            jpanel main_panel = new jpanel();           main_panel.add(aggregates);             jscrollpane scrpane = new jscrollpane(main_panel);           scrpane.getverticalscrollbar().setunitincrement(16);           scrpane.setborder(borderfactory.createemptyborder());           scrpane.getinsets().set(0, 0, 0, 0);           contentpane.add(scrpane);           setcontentpane(contentpane);               }            public static void addparameterslayout(gridbaglayout gbl,           int[] columnwidths, int[] rowheights, double[] columnweights,           double[] rowweights) {           gbl.columnwidths = columnwidths;           gbl.rowheights = rowheights;           gbl.columnweights = columnweights;           gbl.rowweights = rowweights;           }             private static void setcontentpane(jpanel contentpane) {           throw new unsupportedoperationexception("not supported yet.");                           //to change body of generated methods, choose tools | templates.           }            } 

some change in code hope works §§thanks