我编写了一个使用 jbox2D 显示圆圈体的代码。但是当运行这段代码时，我得到了空白屏幕。现在如何在屏幕上显示这个刚体。我需要使用任何视图在屏幕上显示它吗？请帮助..
import org.jbox2d.collision.shapes.CircleShape;
import org.jbox2d.common.Vec2;
import org.jbox2d.dynamics.Body;
import org.jbox2d.dynamics.BodyDef;
import org.jbox2d.dynamics.BodyType;
import org.jbox2d.dynamics.FixtureDef;
import org.jbox2d.dynamics.World;
import android.app.Activity;
import android.os.Bundle;
public class FirstBox2DGameActivity extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// setContentView(R.layout.main);
Vec2 gravity = new Vec2(0.0f, -10.0f);
boolean doSleep = true;
World world = new World(gravity, doSleep);
// Body definition is created as below.
BodyDef bd = new BodyDef();
bd.position.set(100, 200);
bd.type = BodyType.STATIC;
// body Shape
CircleShape cs = new CircleShape();
cs.m_radius = 5.0f;
// Fixture defines the material properties of the body. Fixtures are
// also used for attaching shape to the body. These material properties
// describe how two bodies should react when they collide with each
// other.
FixtureDef fd = new FixtureDef();
fd.shape = cs;
fd.density = 0.5f;
fd.friction = 0.3f;
fd.restitution = 0.5f;
// Now final step is to create a body and add fixture to it. The bodies
// are created using World class.
Body body = world.createBody(bd);
body.createFixture(fd);
}
}