无法查看JComboBox或JCheckBox

我想用Swing Forms制作一个Java应用程序。但我有个问题。我可以看到所有文本框、所有按钮和标签。但没有办法看到JComboBox。与JCheckBox相同。问题在哪里?

import javax.swing.*;
import javax.swing.event.ListDataEvent;
import javax.swing.event.ListDataListener;
import javax.swing.text.DefaultCaret;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.font.TextAttribute;
import java.io.File;
import java.util.Map;
import java.util.Vector;


public class Testtool{
    private JFrame frame;
    private JTextArea taAusgabe;
    private JFileChooser file1;
    private JFileChooser file2;
    private JComboBox cbFormate;
    private DefaultComboBoxModel cbmFormate;

    public JButton btn1;
    public JButton btn2;
    public JButton btn3;
    public JButton btnClear;
    public JLabel laLoading;

    private boolean debug = false;

    private static Testtool window;

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    window = new Testtool();
                    window.frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    public Testtool() throws InterruptedException {
        Vector<String> formate = new Vector<String>();
        formate.add("Format");
        formate.add("1");
        formate.add("2");

        frame = new JFrame();
        frame.setLayout(new BorderLayout());
        frame.setBounds(100, 100, 720, 510);
        frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        frame.setResizable(false);            

        Container container = frame.getContentPane();

        Font header = new Font("Serif", Font.BOLD, 22);
        Map attributes = header.getAttributes();
        attributes.put(TextAttribute.UNDERLINE, TextAttribute.UNDERLINE_ON);

        Font normal = new Font("Serif", Font.BOLD, 16);

        JLabel laHeader = new JLabel();
        laHeader.setHorizontalAlignment(SwingConstants.CENTER);
        laHeader.setText("Testtool für Transformationsskripte");
        laHeader.setFont(header.deriveFont(attributes));
        laHeader.setSize(740, 40);
        laHeader.setLocation(0, 10);
        container.add(laHeader);

        JLabel laFormat = new JLabel();
        laFormat.setText("Format:");
        laFormat.setFont(normal);
        laFormat.setSize(160, 20);
        laFormat.setLocation(10, 80);
        container.add(laFormat);

        cbFormate = new JComboBox();
        cbmFormate = new DefaultComboBoxModel(formate);
        cbFormate.setModel(cbmFormate);
        cbFormate.setLocation(60, 80);
        container.add(cbFormate);

        JLabel la1= new JLabel();
        la1.setText("Messwertdatei:");
        la1.setFont(normal);
        la1.setSize(160, 20);
        la1.setLocation(10, 110);
        container.add(la1);


        final JLabel la2 = new JLabel();
        la2 .setSize(410, 20);
        la2 .setLocation(300, 110);
        container.add(la2 );

        btn1= new JButton();
        btn1.setText("Auswählen");
        btn1.setSize(100, 20);
        btn1.setLocation(180, 110);
        btn1.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent arg0) {
                file1= new JFileChooser();
                int returnVal1 = file1.showOpenDialog(null);
                if (returnVal1 == JFileChooser.APPROVE_OPTION) {
                    File f1= file1.getSelectedFile();
                    la2 .setText(f1.getAbsolutePath());
                    addLogLine(f1.getAbsolutePath() + " ausgewählt", false);
                }
            }
        });
        container.add(btn1);


        final JLabel la3= new JLabel();
        la3.setText("Transformationsskript:");
        la3.setFont(normal);
        la3.setSize(160, 20);
        la3.setLocation(10, 140);
        container.add(la3);

        final JLabel la4= new JLabel();
        la4.setSize(410, 20);
        la4.setLocation(300, 140);
        container.add(la4);

        btn2 = new JButton();
        btn2 .setText("Auswählen");
        btn2 .setSize(100, 20);
        btn2 .setLocation(180, 140);
        btn2 .addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent arg0) {
                file2= new JFileChooser();
                int returnVal2 = file2.showOpenDialog(null);
                if (returnVal2 == JFileChooser.APPROVE_OPTION) {
                    File f2= f2.getSelectedFile();
                    la4.setText(f2.getAbsolutePath());
                    addLogLine(f2.getAbsolutePath() + " ausgewählt", false);
                }
            }
        });
        container.add(btn2 );

        btn3 = new JButton();
        btn3.setText("go");
        btn3.setSize(270, 20);
        btn3.setLocation(10, 170);
        btn3.addMouseListener(new MouseAdapter() {
            public void mousePressed(MouseEvent e) {
                start();
            }

            public void mouseClicked(MouseEvent arg0) {

            }
        });
        container.add(btn3 );

        ImageIcon loading = new ImageIcon(getClass().getClassLoader().getResource("ajax-loader.gif"));
        laLoading = new JLabel();
        laLoading.setVisible(false);
        laLoading.setIcon(loading);
        laLoading.setSize(20, 20);
        laLoading.setLocation(300, 170);
        container.add(laLoading);

        JLabel laAusgabe = new JLabel();
        laAusgabe.setText("Ausgabe:");
        laAusgabe.setFont(normal);
        laAusgabe.setSize(100, 20);
        laAusgabe.setLocation(10, 200);
        container.add(laAusgabe);

        btnClear = new JButton();
        btnClear.setText("Ausgabe löschen");
        btnClear.setSize(160, 20);
        btnClear.setLocation(120, 200);
        btnClear.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent arg0) {
                taAusgabe.setText("");
            }
        });
        container.add(btnClear);

        final JButton btnDebug = new JButton();
        btnDebug.setText("Debugging: AUS");
        btnDebug.setSize(160, 20);
        btnDebug.setLocation(540, 200);
        btnDebug.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent arg0) {

            }
        });
        container.add(btnDebug);

        taAusgabe = new JTextArea();
        DefaultCaret caret = (DefaultCaret)taAusgabe.getCaret();
        caret.setUpdatePolicy(DefaultCaret.ALWAYS_UPDATE);
        taAusgabe.setSize(690, 250);
        taAusgabe.setBackground(container.getBackground());
        taAusgabe.setEditable(false);

        JScrollPane scroll = new JScrollPane(taAusgabe, JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED, JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
        scroll.setLocation(10, 220);
        scroll.setSize(690, 250);
        scroll.setAutoscrolls(true);
            container.add(scroll);       

container.setLayout(null);  


    }

    public void addLogLine(String logline, boolean debug){
        if (this.debug){
            taAusgabe.append(logline + '\n');
        }
        else{
            if(!debug){
                taAusgabe.append(logline + '\n');
            }
        }
    }

    public void stop(){
        btnClear.setEnabled(true);
        btn1.setEnabled(true);
        btn2 .setEnabled(true);
        btn3.setEnabled(true);
        laLoading.setVisible(false);
    }

    public void start(){
        btnClear.setEnabled(false);
        btn1.setEnabled(false);
        btn2 .setEnabled(false);
        btn3.setEnabled(false);
        laLoading.setVisible(true);
    }
}