docs(bindings/java): for BlockingOperator

bindings/java/README.md

@@ -57,3 +57,11 @@ You can run tests with the following command:
 ```shell
 mvn clean verify
 ```
+
+Additionally, this project uses [spotless](https://github.com/diffplug/spotless) for code formatting so that all developers share a consistent code style without bikeshedding on it.
+
+You can apply the code style with the following command::
+
+```shell
+mvn spotless:apply
+```

bindings/java/pom.xml

@@ -60,6 +60,7 @@
 
         <maven-surefire-plugin.version>3.0.0</maven-surefire-plugin.version>
         <exec-maven-plugin.version>3.1.0</exec-maven-plugin.version>
+        <spotless.version>2.37.0</spotless.version>
     </properties>
 
     <dependencyManagement>
@@ -196,6 +197,34 @@
                     </execution>
                 </executions>
             </plugin>
+
+            <plugin>
+                <groupId>com.diffplug.spotless</groupId>
+                <artifactId>spotless-maven-plugin</artifactId>
+                <version>${spotless.version}</version>
+                <configuration>
+                    <java>
+                        <palantirJavaFormat>
+                            <version>2.30.0</version>
+                        </palantirJavaFormat>
+                        <!-- static imports first, then others, no blank lines  -->
+                        <importOrder>
+                            <order>\#|</order>
+                        </importOrder>
+                        <removeUnusedImports/>
+                        <trimTrailingWhitespace/>
+                        <endWithNewline/>
+                    </java>
+                </configuration>
+                <executions>
+                    <execution>
+                        <id>codestyle</id>
+                        <goals>
+                            <goal>check</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
         </plugins>
     </build>
 </project>

bindings/java/src/main/java/org/apache/opendal/BlockingOperator.java

@@ -21,7 +21,21 @@
 
 import java.util.Map;
 
+/**
+ * A blocking operator represents an underneath OpenDAL operator that
+ * accesses data synchronously.
+ */
 public class BlockingOperator extends NativeObject {
+    /**
+     * Construct a blocking operator:
+     *
+     * <p>
+     * You can find all possible schemes <a href="https://docs.rs/opendal/latest/opendal/enum.Scheme.html">here</a>
+     * and see what config options each service supports.
+     *
+     * @param schema the name of the underneath service to access data from.
+     * @param map a map of properties to construct the underneath operator.
+     */
     public BlockingOperator(String schema, Map<String, String> map) {
         super(constructor(schema, map));
     }
@@ -30,12 +44,12 @@ public void write(String fileName, String content) {
         write(nativeHandle, fileName, content);
     }
 
-    public String read(String s) {
-        return read(nativeHandle, s);
+    public String read(String fileName) {
+        return read(nativeHandle, fileName);
     }
 
-    public void delete(String s) {
-        delete(nativeHandle, s);
+    public void delete(String fileName) {
+        delete(nativeHandle, fileName);
     }
 
     public Metadata stat(String fileName) {
@@ -46,8 +60,12 @@ public Metadata stat(String fileName) {
     protected native void disposeInternal(long handle);
 
     private static native long constructor(String schema, Map<String, String> map);
+
     private static native void write(long nativeHandle, String fileName, String content);
+
     private static native String read(long nativeHandle, String fileName);
+
     private static native void delete(long nativeHandle, String fileName);
+
     private static native long stat(long nativeHandle, String file);
 }

bindings/java/src/main/java/org/apache/opendal/Environment.java

@@ -60,5 +60,4 @@ public static String getClassifier() {
     public static String getVersion() {
         return INSTANCE.projectVersion;
     }
-
 }

bindings/java/src/main/java/org/apache/opendal/Metadata.java

@@ -34,6 +34,8 @@ public long getContentLength() {
 
     @Override
     protected native void disposeInternal(long handle);
+
     private static native boolean isFile(long nativeHandle);
+
     private static native long getContentLength(long nativeHandle);
 }

bindings/java/src/main/java/org/apache/opendal/NativeObject.java

@@ -30,8 +30,7 @@ private enum LibraryState {
         LOADED
     }
 
-    private static final AtomicReference<LibraryState> libraryLoaded =
-        new AtomicReference<>(LibraryState.NOT_LOADED);
+    private static final AtomicReference<LibraryState> libraryLoaded = new AtomicReference<>(LibraryState.NOT_LOADED);
 
     static {
         NativeObject.loadLibrary();
@@ -43,11 +42,7 @@ public static void loadLibrary() {
         }
 
         if (libraryLoaded.compareAndSet(LibraryState.NOT_LOADED, LibraryState.LOADING)) {
-            JarJniLoader.loadLib(
-                NativeObject.class,
-                "/native",
-                "opendal_java",
-                Environment.getClassifier());
+            JarJniLoader.loadLib(NativeObject.class, "/native", "opendal_java", Environment.getClassifier());
             libraryLoaded.set(LibraryState.LOADED);
             return;
         }

bindings/java/src/main/java/org/apache/opendal/Operator.java

@@ -25,7 +25,7 @@
 import java.util.concurrent.ConcurrentHashMap;
 
 public class Operator extends NativeObject {
-    private static AsyncRegistry registry()  {
+    private static AsyncRegistry registry() {
         return AsyncRegistry.INSTANCE;
     }
 
@@ -84,7 +84,10 @@ public CompletableFuture<String> read(String fileName) {
     protected native void disposeInternal(long handle);
 
     private static native long constructor(String schema, Map<String, String> map);
+
     private static native long read(long nativeHandle, String fileName);
+
     private static native long write(long nativeHandle, String fileName, String content);
+
     private static native long stat(long nativeHandle, String file);
 }

bindings/java/src/test/java/org/apache/opendal/AsyncStepsTest.java

@@ -19,17 +19,15 @@
 
 package org.apache.opendal;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 import io.cucumber.java.en.Given;
 import io.cucumber.java.en.Then;
 import io.cucumber.java.en.When;
 import java.util.HashMap;
 import java.util.Map;
 
-import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertFalse;
-import static org.junit.jupiter.api.Assertions.assertNotNull;
-import static org.junit.jupiter.api.Assertions.assertTrue;
-
 public class AsyncStepsTest {
     Operator op;
 

bindings/java/src/test/java/org/apache/opendal/BlockingOperatorTest.java

@@ -46,9 +46,9 @@ public void clean() {
     @Test
     public void testStatNotExistFile() {
         assertThatExceptionOfType(OpenDALException.class)
-            .isThrownBy(() -> op.stat("nonexistence"))
-            .extracting(OpenDALException::getCode)
-            .isEqualTo(OpenDALException.Code.NotFound);
+                .isThrownBy(() -> op.stat("nonexistence"))
+                .extracting(OpenDALException::getCode)
+                .isEqualTo(OpenDALException.Code.NotFound);
     }
 
     @Test
@@ -57,8 +57,8 @@ public void testCreateAndDelete() {
         assertThat(op.read("testCreateAndDelete")).isEqualTo("Odin");
         op.delete("testCreateAndDelete");
         assertThatExceptionOfType(OpenDALException.class)
-            .isThrownBy(() -> op.stat("testCreateAndDelete"))
-            .extracting(OpenDALException::getCode)
-            .isEqualTo(OpenDALException.Code.NotFound);
+                .isThrownBy(() -> op.stat("testCreateAndDelete"))
+                .extracting(OpenDALException::getCode)
+                .isEqualTo(OpenDALException.Code.NotFound);
     }
 }

bindings/java/src/test/java/org/apache/opendal/CucumberTest.java

@@ -19,17 +19,14 @@
 
 package org.apache.opendal;
 
+import static io.cucumber.junit.platform.engine.Constants.GLUE_PROPERTY_NAME;
 import org.junit.platform.suite.api.ConfigurationParameter;
 import org.junit.platform.suite.api.IncludeEngines;
 import org.junit.platform.suite.api.SelectClasspathResource;
 import org.junit.platform.suite.api.Suite;
 
-import static io.cucumber.junit.platform.engine.Constants.GLUE_PROPERTY_NAME;
-
 @Suite
 @IncludeEngines("cucumber")
 @SelectClasspathResource("features")
 @ConfigurationParameter(key = GLUE_PROPERTY_NAME, value = "org.apache.opendal")
-public class CucumberTest {
-
-}
+public class CucumberTest {}

bindings/java/src/test/java/org/apache/opendal/StepsTest.java

@@ -19,16 +19,15 @@
 
 package org.apache.opendal;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 import io.cucumber.java.en.Given;
 import io.cucumber.java.en.Then;
 import io.cucumber.java.en.When;
 import java.util.HashMap;
 import java.util.Map;
 
-import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertNotNull;
-import static org.junit.jupiter.api.Assertions.assertTrue;
-
 public class StepsTest {
     BlockingOperator op;
 
@@ -50,7 +49,6 @@ public void the_blocking_file_test_should_exist(String fileName) {
         assertNotNull(metadata);
     }
 
-
     @Then("The blocking file {string} entry mode must be file")
     public void the_blocking_file_test_entry_mode_must_be_file(String fileName) {
         Metadata metadata = op.stat(fileName);