8316627: JViewport Test headless failure

Reviewed-by: dcubed, prr

test/jdk/javax/swing/JViewport/bug4546474.java

@@ -28,46 +28,23 @@
  * @run main bug4546474
  */
 
-import java.awt.Dimension;
-import java.awt.Robot;
-
 import javax.swing.JPanel;
 import javax.swing.JScrollBar;
 import javax.swing.JScrollPane;
-import javax.swing.SwingUtilities;
 
 public class bug4546474 {
-    static JScrollPane scrollpane;
-    static JScrollBar sbar;
-    static volatile boolean viewChanged;
+    public static void main(String[] args) {
+        JPanel panel = new JPanel();
+        JScrollPane scrollpane = new JScrollPane(panel,
+                JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
+                JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
+        JScrollBar sbar = scrollpane.getVerticalScrollBar();
 
-    public static void main(String[] args) throws Exception {
-        SwingUtilities.invokeAndWait(() -> {
-            JPanel panel = new JPanel();
-            panel.setPreferredSize(new Dimension(500, 500));
-            scrollpane = new JScrollPane(panel,
-                    JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
-                    JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
-            sbar = scrollpane.getVerticalScrollBar();
-        });
+        scrollpane.setViewportView(null);
 
-        Robot robot = new Robot();
-        robot.delay(500);
-        SwingUtilities.invokeAndWait(() -> {
-            sbar.addAdjustmentListener(e -> viewChanged = true);
-            scrollpane.setViewportView(null);
-        });
-        robot.delay(500);
-        if (!viewChanged) {
-            viewChanged = true;
+        if (sbar.getVisibleAmount() > 0) {
+            throw new RuntimeException("Vertical scrollbar is not " +
+                    "updated when viewport is replaced");
         }
-        robot.delay(500);
-
-        SwingUtilities.invokeAndWait(() -> {
-            if (sbar.getVisibleAmount() > 0) {
-                throw new RuntimeException("Vertical scrollbar is not " +
-                        "updated when viewport is replaced");
-            }
-        });
     }
 }