[Java] Add java exception check in JNI (#6378)

java/runtime/src/main/java/org/ray/runtime/util/JniExceptionUtil.java

@@ -0,0 +1,19 @@
+package org.ray.runtime.util;
+
+import org.apache.commons.lang3.exception.ExceptionUtils;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+// Required by JNI macro RAY_CHECK_JAVA_EXCEPTION
+public final class JniExceptionUtil {
+
+  private static final Logger LOGGER = LoggerFactory.getLogger(JniExceptionUtil.class);
+
+  public static String getStackTrace(String fileName, int lineNumber, String function,
+      Throwable throwable) {
+    LOGGER.error("An unexpected exception occurred while executing Java code from JNI ({}:{} {}).",
+        fileName, lineNumber, function, throwable);
+    // Return the exception in string form to JNI.
+    return ExceptionUtils.getStackTrace(throwable);
+  }
+}