import java.awt.*;import javax.swing.*;import java.awt.event.*;abstract class MTank extends JFrame{    public int x, y;    public Image image;    Image ima;    public boolean up = false,  down = false,  left = false,  right = false;    boolean FlagUp,FlagDown,FlagLeft,FlagRight;    boolean life;    int sleepTime;    int lifetime;    int sign;    int time;    int Type;    int BallType;    MTank() {    }   }