Review

PlotRenderingInfo.getOwner() may return null.

Check for null.

• missing/condition/null_check

org/jfree/chart/axis/Axis.java

drawLabel(String, Graphics2D, Rectangle2D, Rectangle2D, RectangleEdge, AxisState, PlotRenderingInfo)

class Axis {
    /**
     * Draws the axis label.
     *
     * @param label  the label text.
     * @param g2  the graphics device.
     * @param plotArea  the plot area.
     * @param dataArea  the area inside the axes.
     * @param edge  the location of the axis.
     * @param state  the axis state (<code>null</code> not permitted).
     * @param plotState  the plot state (<code>null</code> permitted).
     *
     * @return Information about the axis.
     */
    protected AxisState drawLabel(String label, Graphics2D g2, 
            Rectangle2D plotArea, Rectangle2D dataArea, RectangleEdge edge, 
            AxisState state, PlotRenderingInfo plotState) {

        // it is unlikely that 'state' will be null, but check anyway...
        if (state == null) {
            throw new IllegalArgumentException("Null 'state' argument.");
        }
        
        if ((label == null) || (label.equals(""))) {
            return state;
        }

        Font font = getLabelFont();
        RectangleInsets insets = getLabelInsets();
        g2.setFont(font);
        g2.setPaint(getLabelPaint());
        FontMetrics fm = g2.getFontMetrics();
        Rectangle2D labelBounds = TextUtilities.getTextBounds(label, g2, fm);
        Shape hotspot = null;
        
        if (edge == RectangleEdge.TOP) {
            AffineTransform t = AffineTransform.getRotateInstance(
                    getLabelAngle(), labelBounds.getCenterX(), 
                    labelBounds.getCenterY());
            Shape rotatedLabelBounds = t.createTransformedShape(labelBounds);
            labelBounds = rotatedLabelBounds.getBounds2D();
            float w = (float) labelBounds.getWidth();
            float h = (float) labelBounds.getHeight();
            float labelx = (float) dataArea.getCenterX();
            float labely = (float) (state.getCursor() - insets.getBottom() 
                    - h / 2.0);
            TextUtilities.drawRotatedString(label, g2, labelx, labely, 
                    TextAnchor.CENTER, getLabelAngle(), TextAnchor.CENTER);
            hotspot = new Rectangle2D.Float(labelx - w / 2.0f, 
                    labely - h / 2.0f, w, h);
            state.cursorUp(insets.getTop() + labelBounds.getHeight() 
                    + insets.getBottom());
        }
        else if (edge == RectangleEdge.BOTTOM) {
            AffineTransform t = AffineTransform.getRotateInstance(
                    getLabelAngle(), labelBounds.getCenterX(), 
                    labelBounds.getCenterY());
            Shape rotatedLabelBounds = t.createTransformedShape(labelBounds);
            labelBounds = rotatedLabelBounds.getBounds2D();
            float w = (float) labelBounds.getWidth();
            float h = (float) labelBounds.getHeight();
            float labelx = (float) dataArea.getCenterX();
            float labely = (float) (state.getCursor() + insets.getTop() 
                    + h / 2.0);
            TextUtilities.drawRotatedString(label, g2, labelx, labely, 
                    TextAnchor.CENTER, getLabelAngle(), TextAnchor.CENTER);
            hotspot = new Rectangle2D.Float(labelx - w / 2.0f, 
                    labely - h / 2.0f, w, h);
            state.cursorDown(insets.getTop() + labelBounds.getHeight() 
                    + insets.getBottom());
        }
        else if (edge == RectangleEdge.LEFT) {
            AffineTransform t = AffineTransform.getRotateInstance(
                    getLabelAngle() - Math.PI / 2.0, labelBounds.getCenterX(), 
                    labelBounds.getCenterY());
            Shape rotatedLabelBounds = t.createTransformedShape(labelBounds);
            labelBounds = rotatedLabelBounds.getBounds2D();
            float w = (float) labelBounds.getWidth();
            float h = (float) labelBounds.getHeight();
            float labelx = (float) (state.getCursor() - insets.getRight() 
                    - w / 2.0);
            float labely = (float) dataArea.getCenterY();
            TextUtilities.drawRotatedString(label, g2, labelx, labely, 
                    TextAnchor.CENTER, getLabelAngle() - Math.PI / 2.0, 
                    TextAnchor.CENTER);
            hotspot = new Rectangle2D.Float(labelx - w / 2.0f, 
                    labely - h / 2.0f, w, h);
            state.cursorLeft(insets.getLeft() + labelBounds.getWidth() 
                    + insets.getRight());
        }
        else if (edge == RectangleEdge.RIGHT) {

            AffineTransform t = AffineTransform.getRotateInstance(
                    getLabelAngle() + Math.PI / 2.0, 
                    labelBounds.getCenterX(), labelBounds.getCenterY());
            Shape rotatedLabelBounds = t.createTransformedShape(labelBounds);
            labelBounds = rotatedLabelBounds.getBounds2D();
            float w = (float) labelBounds.getWidth();
            float h = (float) labelBounds.getHeight();
            float labelx = (float) (state.getCursor() 
                            + insets.getLeft() + w / 2.0);
            float labely = (float) (dataArea.getY() + dataArea.getHeight() 
                    / 2.0);
            TextUtilities.drawRotatedString(label, g2, labelx, labely, 
                    TextAnchor.CENTER, getLabelAngle() + Math.PI / 2.0, 
                    TextAnchor.CENTER);
            hotspot = new Rectangle2D.Float(labelx - w / 2.0f, 
                    labely - h / 2.0f, w, h);
            state.cursorRight(insets.getLeft() + labelBounds.getWidth() 
                    + insets.getRight());

        }
        if (plotState != null && hotspot != null) {
            EntityCollection entities = plotState.getOwner()
                    .getEntityCollection();
            if (entities != null) {
                entities.add(new AxisLabelEntity(this, hotspot, 
                        this.labelToolTip, this.labelURL));
            }
        }
        return state;

    }

}

class CheckForNoOwner {
  void pattern(PlotRenderingInfo plotState, AxisLabelEntity someEntity) {
    ChartRenderingInfo owner = plotState.getOwner();
    if (owner != null) {
      EntityCollection entities = owner.getEntityCollection();
      if (entities != null) {
        entities.add(someEntity);
      }
    }
  }
}