Java文本域滚动条的位置 java文本框滚动条

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class JScrollPaneTest extends JFrame{
    public JScrollPaneTest(){
        Container container = getContentPane();
        container.setLayout(new GridLayout(2,2,10,10));
        JPanel p2 = new JPanel(new BorderLayout());
        p2.add(new JButton("b2"),BorderLayout.SOUTH);
        JTextArea ta = new JTextArea(20,50);
        JScrollPane sp = new JScrollPane(ta);
        container.add(sp);
        container.add(p2);
        setTitle("带滚动条的文字编辑器");
        setSize(400,400);
        setVisible(true);
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    }

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

/*public class JTextFieldTest extends JFrame{
    public JTextFieldTest() {
        Container container = getContentPane();
        container.setLayout(new FlowLayout());
        JTextField jt = new JTextField("aaa");
        jt.setColumns(20);
        jt.setFont(new Font("宋体",Font.PLAIN,20));
        JButton jb = new JButton("清除");
        jt.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                jt.setText("触发事件");
            }
        });
        jb.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                System.out.println(jt.getText());
                jt.setText("");
                jt.requestFocus();
            }
        });
        container.add(jt);
        container.add(jb);
        setBounds(100,100,250,110);
        setVisible(true);
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    }

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


}*/