Small changes to truth checks

Changes to compile with strict version of NPE checks enabled under
ecj/tycho.

Author: Jason Faust

net.sourceforge.pmd.eclipse.plugin/src/main/java/net/sourceforge/pmd/eclipse/ui/preferences/PMDPreferencePage.java

@@ -574,7 +574,7 @@ public void widgetSelected(SelectionEvent event) {
                             flContinue = input.open() == InputDialog.OK;
                         }
 
-                        if (flContinue) {
+                        if (flContinue && input != null) {
                             ruleSet = RuleSetUtil.setNameDescription(ruleSet,
                                     getFileNameWithoutExtension(file.getName()), input.getValue());
                             OutputStream out = new FileOutputStream(fileName);

net.sourceforge.pmd.eclipse.plugin/src/main/java/net/sourceforge/pmd/eclipse/ui/preferences/br/RuleTableManager.java

@@ -398,7 +398,7 @@ private void exportTo(String fileName, Shell shell) throws FileNotFoundException
             flContinue = input.open() == Window.OK;
         }
 
-        if (flContinue) {
+        if (flContinue && input != null) {
             OutputStream out = null;
             try {
                 ruleSet = RuleSetUtil.setNameDescription(ruleSet, FileUtil.getFileNameWithoutExtension(file.getName()),

net.sourceforge.pmd.eclipse.plugin/src/main/java/net/sourceforge/pmd/eclipse/ui/preferences/panelmanagers/RulePanelManager.java

@@ -146,7 +146,7 @@ private void showLanguageVersionFields(Language language) {
         minLanguageVersionCombo.setVisible(hasVersions);
         maxLanguageVersionCombo.setVisible(hasVersions);
 
-        if (hasVersions) {
+        if (hasVersions && language != null) {
             List<LanguageVersion> versions = new ArrayList<LanguageVersion>();
             versions.add(null); // allow no selection
             versions.addAll(language.getVersions());