Preguntas sobre programación simple de JAVA, responda con atención

importar?javax.swing.*;

importar?java.awt.*;

importar?java.awt.event.MouseEvent;

importar?java.awt.event.MouseListener;

importar?java.awt.event.MouseMotionListener;

¿clase?pública?CirclePanel?extends?JPanel?{

privado?int?x;

privado?int?y;

privado?int?radio;

privado?int?mouseDiffX ?=?0;

privado?int?mouseDiffY?=?0;

privado?boolean?activado?=?false;

público?CirclePanel( final?int?x,?final?int?y,?final?int?radius){

super();

this.x?=?x;

este.y?=?y;

este.radio?=?radio;

addMouseListener(new?MouseListener()?{

@Override

public?void?mouseClicked(final?MouseEvent?mouseEvent)?{}

@Override

public?void?mousePressed(final?MouseEvent? mouseEvent)?{

mouseDiffX?=?mouseEvent.getX()?-?CirclePanel.this.x;

mouseDiffY?=?mouseEvent.getY()?-?CirclePanel. this.y;

activado?=?mouseEvent.getPoint().distance(

new?Point(CirclePanel.this.x,?CirclePanel.this.y))?< ?radio;

}

@Override

public?void?mouseReleased(final?MouseEvent?mouseEvent)?{activated?=?false;}

@Override

público?void?mouseEntered(final?MouseEvent?mouseEvent)?{}

@Override

public?void?mouseExited (final?MouseEvent?mouseEvent)?{}

});

addMouseMotionListener(new?MouseMotionListener()?{

@Override

public?void?mouseDragged(final?MouseEvent?mouseEvent)?{

if(activado){

CirclePanel.this.x?=?mouseEvent.getX()?- ?mus

eDiffX;

CirclePanel.this.y?=?mouseEvent.getY()?-?mouseDiffY;

paintComponent(CirclePanel.this.getGraphics());

}

}

@Override

public?void?mouseMoved(final?MouseEvent?mouseEvent)?{}

} );

}

@Override

¿protegido?void?paintComponent(final?Graphics?graphics)?{

super.paintComponent (gráficos);

graphics.drawOval(x,?y,?radius,?radius);

}

public?static?void?main( String[]?args)?{

final?JFrame?f?=?new?JFrame("Prueba");

f.setSize(500,?500);

f.setVisible(true);

f.getContentPane().add(new?CirclePanel(40,?40,?50));

f .setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

}

}