netBeans错误报告（未提供详细信息）

Question

当我在下面运行该程序时，netBeans报告“一个或多个项目编译有错误”，但没有提供有关这些错误是什么的指示。 但是，接着说构建成功，并根据需要绘制了Bezier曲线。 有谁知道a）报告存在错误但没有给出任何错误指示的决定背后的想法是什么？ b）如何找出错误所在？

/*
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 * and open the template in the editor.
 */
package curve2;

/**
 *
 * @author User
 */
import java.awt.*;
    import java.util.*;
    import java.awt.geom.Point2D;
    import java.awt.geom.CubicCurve2D;
        import org.jfree.ui.ApplicationFrame;

public class Curve2 extends ApplicationFrame {
        // Set control points
        private int x1 = 200;
        private int y1 = 200;

        private int ctrlx = 300;
        private int ctrly = 300;

        private int x2 = 300;
        private int y2 = 500;

        // Construct frame
        public Curve2() {
              super("First Bezier Curve");
        setSize(600, 600);
            //centre();
            setVisible(true);
        }

        public void paint(Graphics g) {
            // Set points
            Point2D.Double P1 = new Point2D.Double(50, 75); // Start Point
        Point2D.Double P2 = new Point2D.Double(150, 75); // End Point
            Point2D.Double ctrl1 = new Point2D.Double(80, 25); // Control Point 1
            Point2D.Double ctrl2 = new Point2D.Double(160, 100); // Control Point 2


            CubicCurve2D.Double cubicCurve; // Cubic curve

            cubicCurve = new CubicCurve2D.Double( P1.x, P1.y, ctrl1.x, ctrl1.y, ctrl2.x, ctrl2.y, P2.x, P2.y);

            Graphics2D g2 = (Graphics2D)g;
            g2.draw(cubicCurve);
        }