Fix redundant null checks (#4326)

* Fix redundant null checks identified by SpotBugs

* Fix redundant nullcheck warnings from SpotBugs

Removed redundant null checks and comparisons in multiple files as identified by SpotBugs.
- Socket.java: Removed check for connection != null.
- GroupLayout.java: Removed check for name != null.
- Form.java: Removed checks for focused != null and atXY != null.
- Resources.java: Removed checks for mediaRules != null.
- Component.java: Removed check for cmp != null.
- Command.java: Removed check for obj != null.
- ComponentSelector.java: Removed check for mgr != null.
- PropertyIndex.java: Removed check for p != null.
- Container.java: Removed check for next != null.
- Display.java: Removed check for dest != null.
- CommonTransitions.java: Removed checks for sourceForm != null and dest != null.
- ResourceThreadQueue.java: Removed check for img == null.
- Other minor cleanup.

* Fix redundant nullcheck warnings from SpotBugs

- Remove redundant null checks in multiple files (Socket.java, Form.java, Component.java, etc.) where values are guaranteed to be non-null or null.
- Update `generate-quality-report.py` to enforce zero tolerance for `RCN_REDUNDANT_NULLCHECK_OF_NONNULL_VALUE` and `RCN_REDUNDANT_NULLCHECK_OF_NULL_VALUE` warnings.
- Fix compilation issues in Socket.java syntax.
- Verify that the build passes with the new quality gate.

* Fix redundant nullcheck warnings and enforce quality gate

- Update generate-quality-report.py to fail build on RCN_REDUNDANT_NULLCHECK violations.
- Remove redundant null checks in multiple files (Objects.java, Component.java, Form.java, etc.).
- Revert unsafe null check removal in Socket.java that caused test failures.
- Add suppression for Socket.java in spotbugs-exclude.xml.
- Cleanup dead code in DefaultLookAndFeel.java and Inflate.java.

---------

Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>

Author: google-labs-jules[bot]

.github/scripts/generate-quality-report.py

@@ -754,6 +754,23 @@ def main() -> None:
     if not generate_html_only:
         REPORT_PATH.write_text(report + "\n", encoding="utf-8")
 
+    # Enforce quality gates
+    spotbugs, _, _ = parse_spotbugs()
+    if spotbugs:
+        forbidden_rules = {
+            "RCN_REDUNDANT_NULLCHECK_OF_NONNULL_VALUE",
+            "RCN_REDUNDANT_NULLCHECK_OF_NULL_VALUE"
+        }
+        violations = [
+            f for f in spotbugs.findings
+            if f.rule in forbidden_rules
+        ]
+        if violations:
+            print("\n❌ Build failed due to forbidden SpotBugs violations:")
+            for v in violations:
+                print(f"  - {v.rule}: {v.location} - {v.message}")
+            exit(1)
+
 
 if __name__ == "__main__":
     main()

CodenameOne/src/com/codename1/compat/java/util/Objects.java

@@ -48,7 +48,7 @@ public static boolean equals(Object a, Object b) {
         if (a == b) {
             return true;
         }
-        return a == null ? b == null : a.equals(b);
+        return a != null && a.equals(b);
     }
 
     /**

CodenameOne/src/com/codename1/io/ConnectionRequest.java

@@ -2747,9 +2747,6 @@ public void run() {
                         if (fs.exists(file)) {
                             try {
                                 EncodedImage img = EncodedImage.create(fs.openInputStream(file), (int) fs.getLength(file));
-                                if (img == null) {
-                                    throw new IOException("Failed to load image at " + file);
-                                }
                                 CallbackDispatcher.dispatchSuccess(onSuccess, img);
                             } catch (Exception ex) {
                                 CallbackDispatcher.dispatchError(onFail, ex);
@@ -2763,9 +2760,6 @@ public void run() {
                         if (fs.exists(file)) {
                             try {
                                 EncodedImage img = EncodedImage.create(fs.createInputStream(file), fs.entrySize(file));
-                                if (img == null) {
-                                    throw new IOException("Failed to load image at " + file);
-                                }
                                 CallbackDispatcher.dispatchSuccess(onSuccess, img);
                             } catch (Exception ex) {
                                 CallbackDispatcher.dispatchError(onFail, ex);

CodenameOne/src/com/codename1/io/gzip/Inflate.java

@@ -151,10 +151,6 @@ int inflateInit(int w) {
             inflateEnd();
             return Z_STREAM_ERROR;
         }
-        if (blocks != null && wbits != w) {
-            blocks.free();
-            blocks = null;
-        }
 
         // set window size
         wbits = w;

CodenameOne/src/com/codename1/l10n/SimpleDateFormat.java

@@ -521,9 +521,7 @@ public Date parse(String source) throws ParseException {
 
                         throwInvalid("timezone", startIndex);
                     }
-                    if (res != null) {
-                        parsedTimeZone = res.timeZone;
-                    }
+                    parsedTimeZone = res.timeZone;
                     tzMinutes = ((tzMinutes == -1) ? 0 : tzMinutes) + v;
                     break;
                 case YEAR_LETTER:
@@ -844,10 +842,11 @@ String readAmPmMarker(String source, int ofs) {
         if (i == -1) {
             i = source.length();
         }
-        String fragment = readSubstring(source, ofs, i).toLowerCase();
+        String fragment = readSubstring(source, ofs, i);
         if (fragment == null) {
             return null;
         }
+        fragment = fragment.toLowerCase();
         DateFormatSymbols ds = getDateFormatSymbols();
         String[] markers = ds.getAmPmStrings();
         for (String marker : markers) {

CodenameOne/src/com/codename1/processing/ContainsEvaluator.java

@@ -73,9 +73,6 @@ private String[] _getLeftValue(StructuredContent element, String lvalue) {
      */
     protected Object evaluateLeftContainsRight(StructuredContent element, String lvalue, String rvalue) {
         String[] lvalues = _getLeftValue(element, lvalue);
-        if (lvalues == null) {
-            return null;
-        }
         // if the rvalue is wrapped with "()", the caller explicitly expects the lvalue to be an array of values,
         // otherwise try to do a "string contains" match first if there's only one lvalue
         if (rvalue.indexOf("(") == -1 && lvalues.length == 1) {

CodenameOne/src/com/codename1/processing/TextEvaluator.java

@@ -80,9 +80,6 @@ private String[] _getLeftValue(StructuredContent element, String lvalue) {
     protected Object evaluateLeftLessRight(StructuredContent element,
                                            String lvalue, String rvalue) {
         String[] v = _getLeftValue(element, lvalue);
-        if (v == null) {
-            return null;
-        }
         int vlen = v.length;
         for (int i = 0; i < vlen; i++) {
             if (isNumeric(rvalue) && isNumeric(v[i])) {
@@ -112,9 +109,6 @@ protected Object evaluateLeftLessRight(StructuredContent element,
     protected Object evaluateLeftGreaterRight(StructuredContent element,
                                               String lvalue, String rvalue) {
         String[] v = _getLeftValue(element, lvalue);
-        if (v == null) {
-            return null;
-        }
         int vlen = v.length;
         for (int i = 0; i < vlen; i++) {
             if (isNumeric(rvalue) && isNumeric(v[i])) {
@@ -144,9 +138,6 @@ protected Object evaluateLeftGreaterRight(StructuredContent element,
     protected Object evaluateLeftEqualsRight(StructuredContent element,
                                              String lvalue, String rvalue) {
         String[] v = _getLeftValue(element, lvalue);
-        if (v == null) {
-            return null;
-        }
         int vlen = v.length;
         for (int i = 0; i < vlen; i++) {
             if (isNumeric(rvalue) && isNumeric(v[i])) {

CodenameOne/src/com/codename1/properties/PropertyIndex.java

@@ -372,9 +372,7 @@ public void populateFromMap(Map<String, Object> m, Class<? extends PropertyBusin
                     if (val instanceof List) {
                         if (p instanceof CollectionProperty) {
                             if (recursiveType != null) {
-                                if (p != null) {
-                                    ((CollectionProperty) p).clear();
-                                }
+                                ((CollectionProperty) p).clear();
                                 for (Object e : (Collection) val) {
                                     if (e instanceof Map) {
                                         Class eType = p.getGenericType();

CodenameOne/src/com/codename1/properties/PropertyXMLElement.java

@@ -61,15 +61,13 @@ public boolean contains(Element element) {
             return true;
         }
         Vector children = getChildren();
-        if (children != null) {
-            int i = 0;
-            while (i < children.size()) {
-                Element child = (Element) children.get(i);
-                if (child.contains(element)) {
-                    return true;
-                }
-                i++;
+        int i = 0;
+        while (i < children.size()) {
+            Element child = (Element) children.get(i);
+            if (child.contains(element)) {
+                return true;
             }
+            i++;
         }
         return false;
     }
@@ -193,17 +191,14 @@ public Element getElementById(String id) {
             return this;
         }
         Vector children = getChildren();
-        if (children != null) {
-            int i = 0;
-            while (i < children.size()) {
-                Element child = (Element) children.get(i);
-                Element match = child.getElementById(id);
-                if (match != null) {
-                    return match;
-                }
-                i++;
+        int i = 0;
+        while (i < children.size()) {
+            Element child = (Element) children.get(i);
+            Element match = child.getElementById(id);
+            if (match != null) {
+                return match;
             }
-
+            i++;
         }
         return null;
     }
@@ -389,10 +384,8 @@ public String toString(String spacing) {
         }
         str += ">\n";
         Vector children = getChildren();
-        if (children != null) {
-            for (int i = 0; i < children.size(); i++) {
-                str += ((Element) children.get(i)).toString(spacing + ' ');
-            }
+        for (int i = 0; i < children.size(); i++) {
+            str += ((Element) children.get(i)).toString(spacing + ' ');
         }
         str += spacing + "</" + getTagName() + ">\n";
         return str;

CodenameOne/src/com/codename1/ui/BrowserComponent.java

@@ -1263,14 +1263,12 @@ public void execute(String js, Object[] params) {
      * @return the string returned from the Javascript call
      */
     public String executeAndReturnString(String javaScript) {
-        if (internal == null) {
-            while (internal == null) {
-                CN.invokeAndBlock(new Runnable() {
-                    public void run() {
-                        Util.sleep(50);
-                    }
-                });
-            }
+        while (internal == null) {
+            CN.invokeAndBlock(new Runnable() {
+                public void run() {
+                    Util.sleep(50);
+                }
+            });
         }
         if (Display.impl.supportsBrowserExecuteAndReturnString(internal)) {
             return Display.impl.browserExecuteAndReturnString(internal, javaScript);