Table and Menu JavaGUI

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.table.DefaultTableModel;
import javax.swing.table.TableModel;
import javax.swing.table.TableRowSorter;

public class DataNilai extends JFrame implements ActionListener{

    JMenuBar bar=new JMenuBar();
    JMenu file=new JMenu("File");
    JMenu nw=new JMenu("New");
    JCheckBoxMenuItem cb=new JCheckBoxMenuItem("Checkbox");
    JRadioButtonMenuItem r1=new JRadioButtonMenuItem("Radio 1");
    JRadioButtonMenuItem r2=new JRadioButtonMenuItem("Radio 2");
    ButtonGroup bG=new ButtonGroup();
    JMenuItem exit=new JMenuItem("Exit");

    DataNilai(){
        menuBar();
        toolBar();
        tabel();
        filter();
        form();
    }

    void menuBar(){
        nw.add(cb);
        nw.addSeparator();
        bG.add(r1);//supaya milih salah satu doank
        bG.add(r2);
        nw.add(r1);//masukin ke new, satu persatu setelah di grup
        nw.add(r2);
        nw.setIcon(new ImageIcon("image/New.png"));//taro gambar
        file.add(nw);
        file.add(exit);exit.addActionListener(this);//supaya bisa exit pas di klik
        file.setMnemonic('F');//supaya f digaris bawah
        bar.add(file);//masukin ke bar
        setJMenuBar(bar);//untuk menu
    }

    JToolBar tb=new JToolBar();
    JButton nwButton=new JButton("New");
    JButton delButton=new JButton("Delete");

    void toolBar(){
        tb.add(nwButton);nwButton.addActionListener(this);//supaya bisa di klik
        tb.add(delButton);delButton.addActionListener(this);
        add(tb,BorderLayout.NORTH);//supaya di atas
    }
    //buat table
    String[] hdr={"ID","Nama","Nilai"};//bikin headernya array of string
    Object[][] data={
        {"001","Andi",90},
        {"002","Budi",89}
    };//bikin data awal pake array of object,* 90 89 di int biar bisa di kondisiin
    DefaultTableModel dtm=new DefaultTableModel(data, hdr);
    JTable tbl=new JTable(dtm);
    TableRowSorter<TableModel>tblS=new TableRowSorter<TableModel>(dtm);
    void tabel(){
        tbl.setRowSorter(tblS);//untuk sort
        add(new JScrollPane(tbl),BorderLayout.CENTER);

    }

    //buat filter
    JPanel p=new JPanel(new FlowLayout());
    JTextField txt=new JTextField(20);
    JButton ftr=new JButton("Filter");

    void filter(){
        p.add(txt);
        p.add(ftr);ftr.addActionListener(this);
        add(p,BorderLayout.SOUTH);
    }
    //buat form
    void form(){
        setExtendedState(MAXIMIZED_BOTH);
        setVisible(true);
        setLocationRelativeTo(null);
        setDefaultCloseOperation(DO_NOTHING_ON_CLOSE);
    }

    public static void main(String[] args) {
        new DataNilai();
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        if(e.getActionCommand().equals("Exit"))
            System.exit(EXIT_ON_CLOSE);
        else if (e.getActionCommand().equals("New")) {
            String nama,id,n;
            int nilai=-1,flag;
            id=JOptionPane.showInputDialog(null,"Masukan ID");
            nama=JOptionPane.showInputDialog(null,"Masukan Nama");
            do{
                flag=0;//kasih flag 0 biar kalo ga ada alnum langsung keluar loop
                n=JOptionPane.showInputDialog(null,"Masukan Nilai");//input biasa
                for (int i = 0; i < n.length(); i++) {//cek satu2
                    if(!Character.isDigit(n.charAt(i))){//kalo ternyata ada huruf
                        flag=1;//ubah flag ke 1 biar loop lagi
                    }
                }
                if (flag!=1) //kalo udah bener angka semua abru diubah ke int
                    nilai=Integer.valueOf(n);
            }while(nilai<0||nilai>100||flag==1);
            dtm.addRow(new Object[]{id,nama,nilai});
        }
        else if (e.getActionCommand().equals("Delete"))
            dtm.removeRow(tbl.convertRowIndexToModel(tbl.getSelectedRow()));
            //di ubah indexnya setelah sort supaya yang diapus sesuai
        else if (e.getActionCommand().equals("Filter")) {
            System.out.println("masuk filter");
            if (txt.getText().isEmpty()) {//kalo syarat kosong
                tblS.setRowFilter(null);//ga ada syarat semua data muncul
            }
            else
                tblS.setRowFilter(RowFilter.regexFilter(txt.getText(), 0));
                //regexfilter, filter yg  disesuaikan dengan isi txt
                //0 maksudnya berdasarkan row 0(ID)
        }
    }
}