关于package

SimpleFrameTest.java

package SimpleFrame;

import java.awt.EventQueue;

import javax.swing.JFrame;

public class SimpleFrameTest {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		EventQueue.invokeLater(new Runnable(){
			@Override
			public void run() {
				SimpleFrame frame = new SimpleFrame();
				frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
				frame.setVisible(true);
			}
		});
	}
}

class SimpleFrame extends JFrame{
	private static final int DEFAULT_WIDTH = 300;
	private static final int DEFAULT_HEIGHT = 200;
	
	public SimpleFrame(){
		setSize(DEFAULT_WIDTH,DEFAULT_HEIGHT);
	}
}

下面编译运行时出现问题

操作如下：

正确方式如下：