java中不出现文本框怎么回事?

java中不出现文本框怎么回事?

import java.awt.Container;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;

import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;

public class TextFile extends JFrame {

private Container c;
private JTextField jtf;//文本框
private JButton jb;//按钮
private JComboBox jc;//下拉框
private JTextArea jta;//文本区
private JScrollPane jsp;

public TextFile() {
this.setTitle("页面展示");
c = this.getContentPane();
GridBagLayout gridbag = new GridBagLayout();
GridBagConstraints gbc = new GridBagConstraints();
this.setLayout(gridbag);

jtf = new JTextField();
jb = new JButton("BUTTON开始");
String[] city = {"下拉框列表", "中", "美", "英"};
jc = new JComboBox(city);
jta = new JTextArea();
jta.setRows(10);//设置文本区列数
jsp = new JScrollPane();

gbc.anchor = GridBagConstraints.NORTH; // 当组件没有空间大时，使组件处在北部
gbc.fill = GridBagConstraints.HORIZONTAL;;

gbc.gridx = 0;//横坐标
gbc.gridy = 0;//纵坐标
gbc.gridwidth = 2;//横占几个网格
jtf.setText("这里是文本框，显示一些东西");
gridbag.setConstraints(jtf, gbc);
c.add(jtf);

gbc.fill = GridBagConstraints.BOTH;
gbc.insets = new Insets(10, 0, 0, 10); // 组件彼此的间距
gbc.gridx = 0;
gbc.gridy = 1;
gbc.gridwidth = 1;
gbc.ipadx = 0; // 组件内部填充空间，即给组件的最小宽度添加多大的空间
gbc.ipady = -100; // 组件内部填充空间，即给组件的最小高度添加多大的空间
gridbag.setConstraints(jc, gbc);
c.add(jc);

gbc.insets = new Insets(10, 0, 10, 0); // 组件彼此的间距
gbc.gridx = 1;
gbc.gridy = 1;
gbc.gridwidth = 1;
gbc.ipadx = 0; // 组件内部填充空间，即给组件的最小宽度添加多大的空间
gbc.ipady = 0; // 组件内部填充空间，即给组件的最小高度添加多大的空间
gridbag.setConstraints(jb, gbc);
c.add(jb);

jta.setText("这里输出内容，可以往下拉");
gbc.insets = new Insets(10, 0, 0, 0); // 组件彼此的间距
gbc.gridx = 0;
gbc.gridy = 3;
gbc.gridwidth = GridBagConstraints.REMAINDER;
jsp.setViewportView(jta);
gridbag.setConstraints(jsp, gbc);
c.add(jsp);

this.pack();
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setResizable(false);
this.setVisible(true);

}

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

swing JF窗体吗？

啥意思呢。 html 还是 jsp呢 还是 java的窗口呢