按钮未出现在JFrame中

我设计了JFrame班级，却遇到了问题，那就是它buttons没有出现在桌子底下。

这是我的代码

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import javax.swing.ImageIcon;
import javax.swing.JApplet;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTable;

public class GalaxyTable2 extends JFrame{ //JApplet

    private static final int PREF_W = 700;
    private static final int PREF_H = 600;
    String[] columnNames
                    = {"Phone Name", "Brief Description", "Picture", "price",
                        "Buy"};

// Create image icons
    ImageIcon Image1 = new ImageIcon(
                    getClass().getResource("s1.png"));
    ImageIcon Image2 = new ImageIcon(
                    getClass().getResource("s2.png"));
    ImageIcon Image3 = new ImageIcon(
                    getClass().getResource("s3.png"));
    ImageIcon Image4 = new ImageIcon(
                    getClass().getResource("s4.png"));
    ImageIcon Image5 = new ImageIcon(
                    getClass().getResource("note.png"));
    ImageIcon Image6 = new ImageIcon(
                    getClass().getResource("note2.png"));
    ImageIcon Image7 = new ImageIcon(
                    getClass().getResource("note3.png"));

    Object[][] rowData = {
        {"Galaxy S", "3G Support,CPU 1GHz",
            Image1, 120, false},
        {"Galaxy S II", "3G Support,CPU 1.2GHz",
            Image2, 170, false},
        {"Galaxy S III", "3G Support,CPU 1.4GHz",
            Image3, 205, false},
        {"Galaxy S4", "4G Support,CPU 1.6GHz",
            Image4, 230, false},
        {"Galaxy Note", "4G Support,CPU 1.4GHz",
            Image5, 190, false},
        {"Galaxy Note2 II", "4G Support,CPU 1.6GHz",
            Image6, 190, false},
        {"Galaxy Note 3", "4G Support,CPU 2.3GHz",
            Image7, 260, false},};

    MyTable ss = new MyTable(
                    rowData, columnNames);

    // Create a table
    JTable jTable1 = new JTable(ss);

    public GalaxyTable2() {
    jTable1.setRowHeight(70);

    add(new JScrollPane(jTable1),
   BorderLayout.CENTER);
   //JFrame f = new JFrame();

   this.setTitle("Galaxy Phones");
   //JButton button = new JButton("Home");
  //button.setSize(new Dimension(200, 500));
  //button.setLocation(400, 500);
  //f.getContentPane().add(button);
  //JButton button2 = new JButton("Confirm");
  //button2.setSize(new Dimension(100, 500));
  //button2.setLocation(100, 300);
  // button2.addActionListener(null);
  //f.getContentPane().add(button2);
  //f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

   this.setSize(800, 700);
  this.setLocation(300, 0);
  }
    @Override

    public Dimension getPreferredSize() {
        return new Dimension(PREF_W, PREF_H);
    }

    public void actionPerformed(ActionEvent e) {
        new AMainFrame7().setVisible(true);
    }

    public static void main(String[] args) {

         GalaxyTable2 b=new GalaxyTable2();



        b.pack();

        Dimension d = Toolkit.getDefaultToolkit().getScreenSize();
        b.setLocation((d.width - b.getSize().width) / 2,
                        (d.height - b.getSize().height) / 2);
        b.setVisible(true);

    }
}

这是我的桌子课

import javax.swing.*;
import javax.swing.table.*;
import java.util.*;

public class MyTable extends DefaultTableModel {
public MyTable() {
  }

  /** Construct a table model with specified data and columnNames */
 public MyTable(Object[][] data, Object[] columnNames) {
 super(data, columnNames);
  } 

 /** Override this method to return a class for the column */
 public Class getColumnClass(int column) {
 return getValueAt(0, column).getClass();
    }

 /** Override this method to return true if cell is editable */
 public boolean isCellEditable(int row, int column) {
 Class columnClass = getColumnClass(column);
 return columnClass != ImageIcon.class &&
  columnClass != Date.class;
     }
     }

更好地向我展示代码中的解决方案。