[MINOR] improvement: Simplify return expression

client-spark/common/src/main/java/org/apache/uniffle/shuffle/manager/ShuffleManagerGrpcService.java

@@ -408,10 +408,8 @@ public boolean resetStageAttemptIfNecessary(int stageAttemptNumber) {
               this.isShuffleServerAssignmented = false;
               this.isClearedMapTrackerBlock = false;
               return false;
-            } else if (this.stageAttemptNumber > stageAttemptNumber) {
-              return true;
             }
-            return false;
+            return this.stageAttemptNumber > stageAttemptNumber;
           });
     }
 
@@ -468,15 +466,10 @@ public boolean incWriteFailureForShuffleServer(
 
     public boolean isNeedReassignForLastStageNumber(int lastStageAttemptNumber) {
       return withReadLock(
-          () -> {
-            if (isStageNeedRetry
-                && !isShuffleServerAssignmented
-                && stageAttemptNumber == lastStageAttemptNumber - 1) {
-              return true;
-            } else {
-              return false;
-            }
-          });
+          () ->
+              isStageNeedRetry
+                  && !isShuffleServerAssignmented
+                  && stageAttemptNumber == lastStageAttemptNumber - 1);
     }
 
     public void setShuffleServerAssignmented(boolean isAssignmented) {
@@ -496,10 +489,7 @@ public void setClearedMapTrackerBlock(boolean isCleared) {
     }
 
     public boolean isClearedMapTrackerBlock() {
-      return withReadLock(
-          () -> {
-            return isClearedMapTrackerBlock;
-          });
+      return withReadLock(() -> isClearedMapTrackerBlock);
     }
   }
 
@@ -583,11 +573,7 @@ public boolean currentPartitionIsFetchFailed(
             if (this.stageAttempt != stageAttempt) {
               return false;
             } else {
-              if (this.partitions[partition] >= shuffleManager.getMaxFetchFailures()) {
-                return true;
-              } else {
-                return false;
-              }
+              return this.partitions[partition] >= shuffleManager.getMaxFetchFailures();
             }
           });
     }

client/src/test/java/org/apache/uniffle/client/ClientUtilsTest.java

@@ -87,10 +87,7 @@ private List<CompletableFuture<Boolean>> getFutures(boolean fail) {
                   LOGGER.info("Finished index: " + index);
                   return true;
                 }
-                if (fail && index == 1) {
-                  return false;
-                }
-                return true;
+                return !fail || index != 1;
               },
               executorService);
       futures.add(future);

common/src/main/java/org/apache/uniffle/common/util/JavaUtils.java

@@ -34,12 +34,8 @@ public class JavaUtils {
   private static final String JAVA_9 = "JAVA_9";
 
   public static boolean isJavaVersionAtLeastJava9() {
-    if (Enums.getIfPresent(JavaVersion.class, JAVA_9).isPresent()
-        && SystemUtils.isJavaVersionAtLeast(JavaVersion.JAVA_9)) {
-      return true;
-    } else {
-      return false;
-    }
+    return Enums.getIfPresent(JavaVersion.class, JAVA_9).isPresent()
+        && SystemUtils.isJavaVersionAtLeast(JavaVersion.JAVA_9);
   }
 
   /** Closes the given object, ignoring IOExceptions. */

server/src/main/java/org/apache/uniffle/server/LocalStorageChecker.java

@@ -328,10 +328,7 @@ boolean checkStorageReadAndWrite() {
       } catch (Exception e) {
         LOG.error("Storage read and write error. Storage dir: {}", storageDir, e);
         // avoid check bad track failure due to lack of disk space
-        if (e.getMessage() != null && DEVICE_NO_SPACE_ERROR_MESSAGE.equals(e.getMessage())) {
-          return true;
-        }
-        return false;
+        return e.getMessage() != null && DEVICE_NO_SPACE_ERROR_MESSAGE.equals(e.getMessage());
       } finally {
         try {
           FileUtils.deleteDirectory(checkDir);

server/src/main/java/org/apache/uniffle/server/RegisterHeartBeat.java

@@ -97,10 +97,7 @@ public void startHeartBeat() {
 
   @VisibleForTesting
   public boolean sendHeartBeat(RssSendHeartBeatRequest request) {
-    if (coordinatorClient.sendHeartBeat(request).getStatusCode() == StatusCode.SUCCESS) {
-      return true;
-    }
-    return false;
+    return coordinatorClient.sendHeartBeat(request).getStatusCode() == StatusCode.SUCCESS;
   }
 
   public long getHeartBeatInterval() {

server/src/main/java/org/apache/uniffle/server/storage/SingleStorageManager.java

@@ -121,10 +121,7 @@ public boolean canWrite(ShuffleDataFlushEvent event) {
     try {
       Storage storage = selectStorage(event);
       // if storage is null, appId may not be registered
-      if (storage == null || !storage.canWrite()) {
-        return false;
-      }
-      return true;
+      return storage != null && storage.canWrite();
     } catch (Exception e) {
       LOG.warn("Exception happened when select storage", e);
       return false;

server/src/test/java/org/apache/uniffle/server/StorageCheckerTest.java

@@ -246,10 +246,7 @@ boolean checkStorageReadAndWrite() {
             throw new IOException("mock");
           }
         } catch (Exception e) {
-          if (e.getMessage() != null && DEVICE_NO_SPACE_ERROR_MESSAGE.equals(e.getMessage())) {
-            return true;
-          }
-          return false;
+          return e.getMessage() != null && DEVICE_NO_SPACE_ERROR_MESSAGE.equals(e.getMessage());
         } finally {
           try {
             FileUtils.deleteDirectory(checkDir);