“即使使用import语句，也找不到符号错误”

Question

[遵循在线教程之后，我试图使用swing创建Java GUI。我尝试过在线搜索答案，但找不到。这是代码：

import javax.swing.BorderFactory;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Container;
import javax.swing.GroupLayout;
import javax.swing.GroupLayout.Alignment;
import javax.swing.JLabel;
import javax.swing;

//Create JFrame Container
public class River
{
public River()
{
    JFrame jframe = new JFrame();
    JPanel panel = new JPanel();
    jframe.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    Container contentPanel = jframe.getContentPane();
    GroupLayout grouplayout = new GroupLayout(contentPanel);
    contentPanel.setLayout(grouplayout);

    JLabel clickMe = new JLabel("Click Here");
    JButton button = new JButton("This Button");

    grouplayout.setHorizontalGroup(
        grouplayout.createSequentialGroup()
            .addComponent(clickMe)
            .addGap(10,20,100)
            .addComponent(button));

    grouplayout.setVerticalGroup(
        groupLayout.createParallelGroup(GroupLayout.Alignment.BASELINE)
            .addComponent(clickMe)
            .addComponent(button));

    jframe.setTitle("Our GUI");
    jframe.pack();
    jframe.setVisible(true);
}
public static void main(String[] args) //main method
{
    new River();
} // end of main
}//end River class

但是，当我尝试使用JGRASP运行代码时，出现以下错误：

River.java:4：错误：找不到符号导入javax.swing.Container;^符号：类容器位置：软件包javax.swingRiver.java:8：错误：程序包javax不存在导入javax.swing;^River.java:22：错误：找不到符号容器contentPanel = jframe.getContentPane（）;^符号：类容器地点：班河River.java:27：错误：找不到符号JButton按钮=新的JButton（“ This Button”）;^符号：类JButton地点：班河River.java:27：错误：找不到符号JButton按钮=新的JButton（“ This Button”）;^符号：类JButton地点：班河River.java:36：错误：找不到符号groupLayout.createParallelGroup（GroupLayout.Alignment.BASELINE）^符号：变量groupLayout地点：班河6个错误

----jGRASP wedge2: exit code for process is 1.
----jGRASP: operation complete.

任何帮助将不胜感激。

Answer 1

替换

import javax.swing.Container;

with

import java.awt.Container;