Improve software updater

core/src/net/sf/openrocket/communication/ReleaseInfo.java

@@ -1,5 +1,6 @@
 package net.sf.openrocket.communication;
 
+import com.sun.istack.NotNull;
 import net.sf.openrocket.util.ArrayList;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -7,6 +8,7 @@ import org.slf4j.LoggerFactory;
 import javax.json.JsonArray;
 import javax.json.JsonObject;
 import java.util.List;
+import java.util.Objects;
 
 /**
  * Class containing info about a GitHub release. All the info is stored in a JSON objects, retrieved using the GitHub
@@ -21,8 +23,8 @@ public class ReleaseInfo {
 
     private static final Logger log = LoggerFactory.getLogger(ReleaseInfo.class);
 
-    public ReleaseInfo(JsonObject obj) {
-        this.obj = obj;
+    public ReleaseInfo(@NotNull JsonObject obj) {
+        this.obj = Objects.requireNonNull(obj, "JsonObject cannot be null");
     }
 
     /**
@@ -30,8 +32,6 @@ public class ReleaseInfo {
      * @return release name (e.g. "15.0.3")
      */
     public String getReleaseName() {
-        if (this.obj == null) return null;
-
         String name = this.obj.get("tag_name").toString();           // Release label is encapsulated in the 'tag_name'-tag
         name = name.replaceAll("^\"+|\"+$", "");    // Remove double quotations in the beginning and end
 
@@ -50,8 +50,9 @@ public class ReleaseInfo {
      * @return release notes (this is the text that explains a certain GitHub release)
      */
     public String getReleaseNotes() {
-        if (this.obj == null) return null;
-        return this.obj.get("body").toString();
+        String releaseNotes = this.obj.get("body").toString();
+        releaseNotes = releaseNotes.replaceAll("^\"+|\"+$", "");    // Remove double quotations in the beginning and end
+        return releaseNotes;
     }
 
     /**
@@ -59,8 +60,9 @@ public class ReleaseInfo {
      * @return release URL (e.g. 'https://github.com/openrocket/openrocket/releases/tag/release-15.03')
      */
     public String getReleaseURL() {
-        if (this.obj == null) return null;
-        return this.obj.get("html_url").toString();
+        String releaseURL = this.obj.get("html_url").toString();
+        releaseURL = releaseURL.replaceAll("^\"+|\"+$", "");    // Remove double quotations in the beginning and end
+        return releaseURL;
     }
 
     /**
@@ -68,7 +70,6 @@ public class ReleaseInfo {
      * @return list of asset download URLs (e.g. 'https://github.com/openrocket/openrocket/releases/download/release-15.03/OpenRocket-15.03-installer.exe')
      */
     public List<String> getAssetURLs() {
-        if (this.obj == null) return null;
         List<String> assetURLs = new ArrayList<>();
 
         JsonArray assets = this.obj.getJsonArray("assets");

core/src/net/sf/openrocket/communication/UpdateInfoRetriever.java

@@ -282,10 +282,12 @@ public class UpdateInfoRetriever {
 		 * This function extracts all the release names that start with the specified preTag.
 		 * If preTag is null, the default release names without a pre-tag, starting with a number, are returned (e.g. '15.03').
 		 * @param names list of release names to filter
-		 * @param preTag pre-tag to filter the names on. If null, no special preTag filtering is applied
+		 * @param preTag pre-tag to filter the names on. If null, return all tags that start with a number
 		 * @return list of names starting with the preTag
 		 */
-		public List<String> filterReleasePreTag(List<String> names, String preTag) {
+		public static List<String> filterReleasePreTag(List<String> names, String preTag) {
+			if (names == null) return null;
+
 			List<String> filteredTags = new LinkedList<>();
 
 			// Filter out the names that are not related to the preTag
@@ -317,7 +319,7 @@ public class UpdateInfoRetriever {
 		 * @param tags filter tags
 		 * @return list of release names containing the filter tag
 		 */
-		public List<String> filterReleaseTags(List<String> names, String[] tags) {
+		public static List<String> filterReleaseTags(List<String> names, String[] tags) {
 			if (names == null) return null;
 			if (tags == null) return names;
 			return names.stream().filter(c -> Arrays.stream(tags)
@@ -330,7 +332,7 @@ public class UpdateInfoRetriever {
 		 * @param names list of release names to filter
 		 * @return list of release names that do not contain a devTag
 		 */
-		public List<String> filterOfficialRelease(List<String> names) {
+		public static List<String> filterOfficialRelease(List<String> names) {
 			if (names == null) return null;
 			return names.stream().filter(c -> Arrays.stream(devTags.keySet().toArray(new String[0]))
 					.noneMatch(c::contains)).collect(Collectors.toList());
@@ -346,7 +348,7 @@ public class UpdateInfoRetriever {
 		 * @param onlyOfficial bool to check whether to only include official (non-test) releases
 		 * @return latest JSON GitHub release object
 		 */
-		public JsonObject getLatestReleaseJSON(JsonArray jsonArr, String preTag, String[] tags, boolean onlyOfficial) throws UpdateCheckerException {
+		public static JsonObject getLatestReleaseJSON(JsonArray jsonArr, String preTag, String[] tags, boolean onlyOfficial) throws UpdateCheckerException {
 			if (jsonArr == null) return null;
 
 			JsonObject latestObj = null;

swing/src/net/sf/openrocket/gui/dialogs/UpdateInfoDialog.java

@@ -84,12 +84,10 @@ public class UpdateInfoDialog extends JDialog {
 
 		// 		Release notes
 		String releaseNotes = release.getReleaseNotes();
-		releaseNotes = releaseNotes.replaceAll("^\"|\"$", "");	// Remove leading and trailing quotations
 		sb.append(MarkdownUtil.toHtml(releaseNotes)).append("<br><br>");
 
 		//		GitHub link
 		String releaseURL = release.getReleaseURL();
-		releaseURL = releaseURL.replaceAll("^\"|\"$", "");	// Remove leading and trailing quotations
 		sb.append(String.format("<a href='%s'>%s</a>", releaseURL, trans.get("update.dlg.updateAvailable.txtPane.readMore")));
 		sb.append("</html>");
 		textPane.addHyperlinkListener(new HyperlinkListener() {