diff --git a/src/core/org/apache/jmeter/resources/messages.properties b/src/core/org/apache/jmeter/resources/messages.properties
index a592bc64ba..11ede70e68 100644
--- a/src/core/org/apache/jmeter/resources/messages.properties
+++ b/src/core/org/apache/jmeter/resources/messages.properties
@@ -442,6 +442,7 @@ ja=Japanese
 jar_file=Jar Files
 java_request=Java Request
 java_request_defaults=Java Request Defaults
+java_request_warning=Classname not found in classpath, ensure you add the required jar
 javascript_expression=JavaScript expression to evaluate
 jexl_expression=JEXL expression to evaluate
 jms_auth_required=Required
diff --git a/src/core/org/apache/jmeter/resources/messages_fr.properties b/src/core/org/apache/jmeter/resources/messages_fr.properties
index 21535b999d..c5bd78f224 100644
--- a/src/core/org/apache/jmeter/resources/messages_fr.properties
+++ b/src/core/org/apache/jmeter/resources/messages_fr.properties
@@ -435,6 +435,7 @@ ja=Japonais
 jar_file=Fichiers .jar
 java_request=Requ\u00EAte Java
 java_request_defaults=Requ\u00EAte Java par d\u00E9faut
+java_request_warning=Class introuvable dans le classpath, veuillez ajouter le jar la contenant
 javascript_expression=Expression JavaScript \u00E0 \u00E9valuer
 jexl_expression=Expression JEXL \u00E0 \u00E9valuer
 jms_auth_required=Obligatoire
diff --git a/src/protocol/java/org/apache/jmeter/protocol/java/config/gui/JavaConfigGui.java b/src/protocol/java/org/apache/jmeter/protocol/java/config/gui/JavaConfigGui.java
index baf1ce76dc..761237d881 100644
--- a/src/protocol/java/org/apache/jmeter/protocol/java/config/gui/JavaConfigGui.java
+++ b/src/protocol/java/org/apache/jmeter/protocol/java/config/gui/JavaConfigGui.java
@@ -19,31 +19,35 @@
 package org.apache.jmeter.protocol.java.config.gui;
 
 import java.awt.BorderLayout;
-import java.awt.event.ActionEvent;
-import java.awt.event.ActionListener;
+import java.awt.Color;
+import java.awt.Font;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
 
-import javax.swing.ComboBoxModel;
-import javax.swing.JComboBox;
+import javax.swing.ImageIcon;
 import javax.swing.JLabel;
 import javax.swing.JPanel;
+import javax.swing.SwingConstants;
+import javax.swing.event.ChangeEvent;
+import javax.swing.event.ChangeListener;
 
 import org.apache.commons.lang3.ArrayUtils;
 import org.apache.jmeter.config.Argument;
 import org.apache.jmeter.config.Arguments;
 import org.apache.jmeter.config.gui.AbstractConfigGui;
 import org.apache.jmeter.config.gui.ArgumentsPanel;
-import org.apache.jmeter.gui.util.HorizontalPanel;
+import org.apache.jmeter.gui.util.VerticalPanel;
 import org.apache.jmeter.protocol.java.config.JavaConfig;
 import org.apache.jmeter.protocol.java.sampler.JavaSampler;
 import org.apache.jmeter.protocol.java.sampler.JavaSamplerClient;
 import org.apache.jmeter.testelement.TestElement;
 import org.apache.jmeter.testelement.property.JMeterProperty;
 import org.apache.jmeter.util.JMeterUtils;
+import org.apache.jorphan.gui.JLabeledChoice;
 import org.apache.jorphan.logging.LoggingManager;
 import org.apache.jorphan.reflect.ClassFinder;
 import org.apache.log.Logger;
@@ -53,14 +57,14 @@ import org.apache.log.Logger;
  * {@link JavaConfig} object.
  *
  */
-public class JavaConfigGui extends AbstractConfigGui implements ActionListener {
-    private static final long serialVersionUID = 240L;
+public class JavaConfigGui extends AbstractConfigGui implements ChangeListener {
+    private static final long serialVersionUID = 241L;
 
     /** Logging */
     private static final Logger log = LoggingManager.getLoggerForClass();
 
     /** A combo box allowing the user to choose a test class. */
-    private JComboBox<String> classnameCombo;
+    private JLabeledChoice classNameLabeledChoice;
 
     /**
      * Indicates whether or not the name of this component should be displayed
@@ -72,6 +76,12 @@ public class JavaConfigGui extends AbstractConfigGui implements ActionListener {
     /** A panel allowing the user to set arguments for this test. */
     private ArgumentsPanel argsPanel;
 
+    /**
+     * Used in case the referenced class is not in classpath or does not implement {@link JavaSamplerClient}
+     */
+    private final JLabel warningLabel;
+
+
     /**
      * Create a new JavaConfigGui as a standalone component.
      */
@@ -90,6 +100,8 @@ public class JavaConfigGui extends AbstractConfigGui implements ActionListener {
      */
     public JavaConfigGui(boolean displayNameField) {
         this.displayName = displayNameField;
+        ImageIcon image = JMeterUtils.getImage("warning.png");
+        warningLabel = new JLabel(JMeterUtils.getResString("java_request_warning"), image, SwingConstants.LEFT); // $NON-NLS-1$
         init();
     }
 
@@ -102,7 +114,7 @@ public class JavaConfigGui extends AbstractConfigGui implements ActionListener {
     /**
      * Initialize the GUI components and layout.
      */
-    private void init() {// called from ctor, so must not be overridable
+    private final void init() {// called from ctor, so must not be overridable
         setLayout(new BorderLayout(0, 5));
 
         if (displayName) {
@@ -140,31 +152,31 @@ public class JavaConfigGui extends AbstractConfigGui implements ActionListener {
             log.debug("Exception getting interfaces.", e);
         }
 
-        JLabel label = new JLabel(JMeterUtils.getResString("protocol_java_classname")); // $NON-NLS-1$
+        classNameLabeledChoice = new JLabeledChoice(JMeterUtils.getResString("protocol_java_classname"), possibleClasses.toArray(ArrayUtils.EMPTY_STRING_ARRAY), true, false);
+        classNameLabeledChoice.addChangeListener(this);
 
-        classnameCombo = new JComboBox<>(possibleClasses.toArray(ArrayUtils.EMPTY_STRING_ARRAY));
-        classnameCombo.addActionListener(this);
-        classnameCombo.setEditable(false);
-        label.setLabelFor(classnameCombo);
-
-        HorizontalPanel panel = new HorizontalPanel();
-        panel.add(label);
-        panel.add(classnameCombo);
+        warningLabel.setForeground(Color.RED);
+        Font font = warningLabel.getFont();
+        warningLabel.setFont(new Font(font.getFontName(), Font.BOLD, (int)(font.getSize()*1.1)));
+        warningLabel.setVisible(false);
 
+        VerticalPanel panel = new VerticalPanel();
+        panel.add(classNameLabeledChoice);
+        panel.add(warningLabel);
         return panel;
     }
 
     /**
-     * Handle action events for this component. This method currently handles
-     * events for the classname combo box.
+     * Handle change events for this component. This method currently handles
+     * events for the classname JLabeledChoice
      *
      * @param evt
      *            the ActionEvent to be handled
      */
     @Override
-    public void actionPerformed(ActionEvent evt) {
-        if (evt.getSource() == classnameCombo) {
-            String className = ((String) classnameCombo.getSelectedItem()).trim();
+    public void stateChanged(ChangeEvent evt) {
+        if (evt.getSource() == classNameLabeledChoice) {
+            String className = classNameLabeledChoice.getText().trim();
             try {
                 JavaSamplerClient client = (JavaSamplerClient) Class.forName(className, true,
                         Thread.currentThread().getContextClassLoader()).newInstance();
@@ -204,8 +216,10 @@ public class JavaConfigGui extends AbstractConfigGui implements ActionListener {
                 }
 
                 argsPanel.configure(newArgs);
+                warningLabel.setVisible(false);
             } catch (Exception e) {
                 log.error("Error getting argument list for " + className, e);
+                warningLabel.setVisible(true);
             }
         }
     }
@@ -229,25 +243,42 @@ public class JavaConfigGui extends AbstractConfigGui implements ActionListener {
         argsPanel.configure((Arguments) config.getProperty(JavaSampler.ARGUMENTS).getObjectValue());
 
         String className = config.getPropertyAsString(JavaSampler.CLASSNAME);
-        if(checkContainsClassName(classnameCombo.getModel(), className)) {
-            classnameCombo.setSelectedItem(className);
-        } else {
+        if(!checkContainsClassName(classNameLabeledChoice, className)) {
+            classNameLabeledChoice.addValue(className);
+        }
+        
+        if(!classOk(className)) {
             log.error("Error setting class:'"+className+"' in JavaSampler "+getName()+", check for a missing jar in your jmeter 'search_paths' and 'plugin_dependency_paths' properties");
+            warningLabel.setVisible(true);
+        } else {
+            warningLabel.setVisible(false);
+        }
+        classNameLabeledChoice.setText(className);
+    }
+
+    /**
+     * 
+     * @param className String class name
+     * @return true if class is ok (exist in classpath and instanceof {@link JavaSamplerClient}
+     */
+    private static boolean classOk(String className) {
+        try {
+            JavaSamplerClient client = (JavaSamplerClient) Class.forName(className, true,
+                    Thread.currentThread().getContextClassLoader()).newInstance();
+            return client instanceof JavaSamplerClient;
+        } catch (Exception ex) {
+            return false;
         }
     }
 
     /**
      * Check combo contains className
-     * @param model ComboBoxModel
+     * @param classnameChoice ComboBoxModel
      * @param className String class name
      * @return boolean
      */
-    private static boolean checkContainsClassName(ComboBoxModel<String> model, String className) {
-        int size = model.getSize();
-        Set<String> set = new HashSet<>(size);
-        for (int i = 0; i < size; i++) {
-            set.add(model.getElementAt(i));
-        }
+    private static boolean checkContainsClassName(JLabeledChoice classnameChoice, String className) {
+        Set<String> set = new HashSet<>(Arrays.asList(classnameChoice.getItems()));
         return set.contains(className);
     }
 
@@ -264,7 +295,7 @@ public class JavaConfigGui extends AbstractConfigGui implements ActionListener {
     public void modifyTestElement(TestElement config) {
         configureTestElement(config);
         ((JavaConfig) config).setArguments((Arguments) argsPanel.createTestElement());
-        ((JavaConfig) config).setClassname(String.valueOf(classnameCombo.getSelectedItem()));
+        ((JavaConfig) config).setClassname(classNameLabeledChoice.getText().trim());
     }
 
     /* (non-Javadoc)
@@ -274,7 +305,8 @@ public class JavaConfigGui extends AbstractConfigGui implements ActionListener {
     public void clearGui() {
         super.clearGui();
         this.displayName = true;
+        this.warningLabel.setVisible(false);
         argsPanel.clearGui();
-        classnameCombo.setSelectedIndex(0);
+        classNameLabeledChoice.setSelectedIndex(0);
     }
 }
diff --git a/xdocs/changes.xml b/xdocs/changes.xml
index 2f66b85e3f..1636a2f9e0 100644
--- a/xdocs/changes.xml
+++ b/xdocs/changes.xml
@@ -190,6 +190,7 @@ JMeter now requires Java 8. Ensure you use most up to date version.
 <h3>Other Samplers</h3>
 <ul>
     <li><bug>603982</bug>Guard Exception handler of the <code>JDBCSampler</code> against null messages</li>
+    <li><bug>55652</bug>JavaSampler silently resets classname if class can not be found</li>
 </ul>
 
 <h3>Controllers</h3>