I was trying to integrate firebase real time database with google app engine app. I was getting this error when calling
> DatabaseReference ref = FirebaseDatabase
> .getInstance()
> .getReference("todoItems");
Stacktrace is
03:21:01.450 Error for /productSync java.lang.NoSuchMethodError: com.google.common.base.Preconditions.checkState(ZLjava/lang/String;Ljava/lang/Object;)V at com.google.firebase.FirebaseApp.checkNotDeleted(FirebaseApp.java:314) at com.google.firebase.FirebaseApp.getOptions(FirebaseApp.java:260) at com.google.firebase.database.FirebaseDatabase.getInstance(FirebaseDatabase.java:80) at in.prago.servlet.ProductDataSync.doGet(ProductDataSync.java:83) at javax.servlet.http.HttpServlet.service(HttpServlet.java:617) at javax.servlet.http.HttpServlet.service(HttpServlet.java:717) at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511) at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166) at com.google.apphosting.utils.servlet.ParseBlobUploadFilter.doFilter(ParseBlobUploadFilter.java:125) at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) at com.google.apphosting.runtime.jetty.SaveSessionFilter.doFilter(SaveSessionFilter.java:37) at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) at com.google.apphosting.utils.servlet.JdbcMySqlConnectionCleanupFilter.doFilter(JdbcMySqlConnectionCleanupFilter.java:60) at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) at com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:48) at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388) at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216) at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182) at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765) at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418) at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.handle(AppVersionHandlerMap.java:257) at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152) at org.mortbay.jetty.Server.handle(Server.java:326) at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542) at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:923) at com.google.apphosting.runtime.jetty.RpcRequestParser.parseAvailable(RpcRequestParser.java:76) at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404) at com.google.apphosting.runtime.jetty.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java:145) at com.google.apphosting.runtime.JavaRuntime$RequestRunnable.dispatchServletRequest(JavaRuntime.java:644) at com.google.apphosting.runtime.JavaRuntime$RequestRunnable.dispatchRequest(JavaRuntime.java:604) at com.google.apphosting.runtime.JavaRuntime$RequestRunnable.run(JavaRuntime.java:574) at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:453) at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:460) at com.google.tracing.CurrentContext.runInContext(CurrentContext.java:293) at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:319) at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:311) at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:457) at com.google.apphosting.runtime.ThreadGroupPool$PoolEntry.run(ThreadGroupPool.java:238) at java.lang.Thread.run(Thread.java:745)
This same problem has been discussed in many forums where people suggested to upgrade Guava 19.0 to Guava 20.0. In my case I was not using any such library, therefore I tried adding both, but it didn't worked out for me. Same error was there every time. I am also adding my pom.xml file just in case someone needs to have a look at it. Any help would be appreciated.
Here is a link to one such forum https://github.com/google/guava/issues/2380
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<packaging>war</packaging>
<version>1.0</version>
<properties>
<appengine.app.version>1</appengine.app.version>
<appengine.target.version>1.9.53</appengine.target.version>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<dependencies>
<dependency>
<groupId>com.google.firebase</groupId>
<artifactId>firebase-admin</artifactId>
<version>5.0.0</version>
</dependency>
<dependency>
<groupId>com.google.guava</groupId>
<artifactId>guava</artifactId>
<version>20.0</version>
</dependency>
<!-- Compile/runtime dependencies -->
<dependency>
<groupId>com.google.endpoints</groupId>
<artifactId>endpoints-framework</artifactId>
<version>2.0.7</version>
</dependency>
<dependency>
<groupId>com.google.appengine</groupId>
<artifactId>appengine-api-1.0-sdk</artifactId>
<version>${appengine.target.version}</version>
</dependency>
<dependency>
<groupId>com.google.appengine</groupId>
<artifactId>appengine-endpoints</artifactId>
<version>${appengine.target.version}</version>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
<version>2.5</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>javax.inject</groupId>
<artifactId>javax.inject</artifactId>
<version>1</version>
</dependency>
<dependency>
<groupId>com.googlecode.objectify</groupId>
<artifactId>objectify</artifactId>
<version>5.0</version>
</dependency>
<dependency>
<groupId>com.google.endpoints</groupId>
<artifactId>endpoints-management-control-appengine</artifactId>
<version>1.0.0-beta.11</version>
</dependency>
<dependency>
<groupId>com.google.endpoints</groupId>
<artifactId>endpoints-framework-auth</artifactId>
<version>1.0.0-beta.11</version>
</dependency>
<!-- Test Dependencies -->
<dependency>
<groupId>com.google.appengine</groupId>
<artifactId>appengine-testing</artifactId>
<version>${appengine.target.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>com.google.appengine</groupId>
<artifactId>appengine-api-stubs</artifactId>
<version>${appengine.target.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.11</version>
</dependency>
</dependencies>
<build>
<outputDirectory>target/${project.artifactId}-${project.version}/WEB-INF/classes</outputDirectory>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<version>2.5.1</version>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.7</source>
<target>1.7</target>
</configuration>
</plugin>
<plugin>
<groupId>com.google.cloud.tools</groupId>
<artifactId>endpoints-framework-maven-plugin</artifactId>
<version>1.0.0-beta5</version>
<configuration>
<!-- plugin configuration -->
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-war-plugin</artifactId>
<version>2.3</version>
<configuration>
<webXml>${project.build.directory}/generated-sources/appengine-endpoints/WEB-INF/web.xml</webXml>
<webResources>
<resource>
<!-- this is relative to the pom.xml directory -->
<directory>${project.build.directory}/generated-sources/appengine-endpoints</directory>
<!-- the list has a default value of ** -->
<includes>
<include>WEB-INF/*.discovery</include>
<include>WEB-INF/*.api</include>
</includes>
</resource>
</webResources>
</configuration>
</plugin>
<plugin>
<groupId>com.google.appengine</groupId>
<artifactId>appengine-maven-plugin</artifactId>
<version>${appengine.target.version}</version>
<configuration>
<enableJarClasses>false</enableJarClasses>
</configuration>
<executions>
<execution>
<goals>
<goal>endpoints_get_discovery_doc</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
<pluginManagement>
<plugins>
<!--This plugin's configuration is used to store Eclipse m2e settings only. It has no influence on the Maven build itself.-->
<plugin>
<groupId>org.eclipse.m2e</groupId>
<artifactId>lifecycle-mapping</artifactId>
<version>1.0.0</version>
<configuration>
<lifecycleMappingMetadata>
<pluginExecutions>
<pluginExecution>
<pluginExecutionFilter>
<groupId>
com.google.appengine
</groupId>
<artifactId>
appengine-maven-plugin
</artifactId>
<versionRange>
[1.9.3,)
</versionRange>
<goals>
<goal>
endpoints_get_discovery_doc
</goal>
</goals>
</pluginExecutionFilter>
<action>
<ignore></ignore>
</action>
</pluginExecution>
</pluginExecutions>
</lifecycleMappingMetadata>
</configuration>
</plugin>
</plugins>
</pluginManagement>
</build>
<groupId>in.prago</groupId>
<artifactId>prago</artifactId>
</project>
Update :
As suggested by Auberon I updated my pom.xml with new version of Objectify 5.1.17 and removed the guava depedency. I tried running the code but the same error coined up again. Here is my stacktrace
> com.google.api.server.spi.SystemService invokeServiceMethod: exception
> occurred while calling backend method (SystemService.java:398)
>
> java.lang.NoSuchMethodError:
> com.google.common.base.Preconditions.checkState(ZLjava/lang/String;Ljava/lang/Object;)V
> at
> com.google.firebase.FirebaseApp.checkNotDeleted(FirebaseApp.java:314)
> at com.google.firebase.FirebaseApp.getOptions(FirebaseApp.java:260)
> at
> com.google.firebase.database.FirebaseDatabase.getInstance(FirebaseDatabase.java:80)
> at
> in.prago.spi.PragoMerchantApi.saveProfile(PragoMerchantApi.java:189)
> at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at
> sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
> at
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
> at java.lang.reflect.Method.invoke(Method.java:42) at
> com.google.api.server.spi.SystemService.invokeServiceMethod(SystemService.java:363)
> at
> com.google.api.server.spi.SystemServiceServlet.execute(SystemServiceServlet.java:113)
> at
> com.google.api.server.spi.SystemServiceServlet.doPost(SystemServiceServlet.java:71)
> at javax.servlet.http.HttpServlet.service(HttpServlet.java:637) at
> javax.servlet.http.HttpServlet.service(HttpServlet.java:717) at
> org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
> at
> org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166)
> at
> com.googlecode.objectify.ObjectifyFilter.doFilter(ObjectifyFilter.java:48)
> at
> org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
> at
> org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
> at
> org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
> at
> org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
> at
> org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
> at
> org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388)
> at
> org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
> at
> org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
> at
> org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
> at
> org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418)
> at
> org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
> at org.mortbay.jetty.Server.handle(Server.java:326) at
> org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
> at
> org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:923)
> at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
> at
> com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:453)
> at
> com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:460)
> at
> com.google.tracing.CurrentContext.runInContext(CurrentContext.java:293)
> at
> com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:319)
> at
> com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:311)
> at
> com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:457)
> at java.lang.Thread.run(Thread.java:745)
http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<packaging>war</packaging>
<version>1.0</version>
<properties>
<appengine.app.version>1</appengine.app.version>
<appengine.target.version>1.9.53</appengine.target.version>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<dependencies>
<dependency>
<groupId>com.google.firebase</groupId>
<artifactId>firebase-admin</artifactId>
<version>5.0.0</version>
</dependency>
<dependency>
<groupId>com.google.endpoints</groupId>
<artifactId>endpoints-framework</artifactId>
<version>2.0.7</version>
</dependency>
<dependency>
<groupId>com.google.appengine</groupId>
<artifactId>appengine-api-1.0-sdk</artifactId>
<version>${appengine.target.version}</version>
</dependency>
<dependency>
<groupId>com.google.appengine</groupId>
<artifactId>appengine-endpoints</artifactId>
<version>${appengine.target.version}</version>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
<version>2.5</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>javax.inject</groupId>
<artifactId>javax.inject</artifactId>
<version>1</version>
</dependency>
<dependency>
<groupId>com.googlecode.objectify</groupId>
<artifactId>objectify</artifactId>
<version>5.1.17</version>
</dependency>
<dependency>
<groupId>com.google.endpoints</groupId>
<artifactId>endpoints-management-control-appengine</artifactId>
<version>1.0.0-beta.11</version>
</dependency>
<dependency>
<groupId>com.google.endpoints</groupId>
<artifactId>endpoints-framework-auth</artifactId>
<version>1.0.0-beta.11</version>
</dependency>
<!-- Test Dependencies -->
<dependency>
<groupId>com.google.appengine</groupId>
<artifactId>appengine-testing</artifactId>
<version>${appengine.target.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>com.google.appengine</groupId>
<artifactId>appengine-api-stubs</artifactId>
<version>${appengine.target.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.11</version>
</dependency>
</dependencies>
<build>
<outputDirectory>target/${project.artifactId}-${project.version}/WEB-INF/classes</outputDirectory>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<version>2.5.1</version>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.7</source>
<target>1.7</target>
</configuration>
</plugin>
<plugin>
<groupId>com.google.cloud.tools</groupId>
<artifactId>endpoints-framework-maven-plugin</artifactId>
<version>1.0.0-beta5</version>
<configuration>
<!-- plugin configuration -->
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-war-plugin</artifactId>
<version>2.3</version>
<configuration>
<webXml>${project.build.directory}/generated-sources/appengine-endpoints/WEB-INF/web.xml</webXml>
<webResources>
<resource>
<!-- this is relative to the pom.xml directory -->
<directory>${project.build.directory}/generated-sources/appengine-endpoints</directory>
<!-- the list has a default value of ** -->
<includes>
<include>WEB-INF/*.discovery</include>
<include>WEB-INF/*.api</include>
</includes>
</resource>
</webResources>
</configuration>
</plugin>
<plugin>
<groupId>com.google.appengine</groupId>
<artifactId>appengine-maven-plugin</artifactId>
<version>${appengine.target.version}</version>
<configuration>
<enableJarClasses>false</enableJarClasses>
</configuration>
<executions>
<execution>
<goals>
<goal>endpoints_get_discovery_doc</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
<pluginManagement>
<plugins>
<!--This plugin's configuration is used to store Eclipse m2e settings only. It has no influence on the Maven build itself.-->
<plugin>
<groupId>org.eclipse.m2e</groupId>
<artifactId>lifecycle-mapping</artifactId>
<version>1.0.0</version>
<configuration>
<lifecycleMappingMetadata>
<pluginExecutions>
<pluginExecution>
<pluginExecutionFilter>
<groupId>
com.google.appengine
</groupId>
<artifactId>
appengine-maven-plugin
</artifactId>
<versionRange>
[1.9.3,)
</versionRange>
<goals>
<goal>
endpoints_get_discovery_doc
</goal>
</goals>
</pluginExecutionFilter>
<action>
<ignore></ignore>
</action>
</pluginExecution>
</pluginExecutions>
</lifecycleMappingMetadata>
</configuration>
</plugin>
</plugins>
</pluginManagement>
</build>
<groupId>in.prago</groupId>
<artifactId>prago</artifactId>
</project>
Include on project Guava newer version dependence.
<dependency>
<groupId>com.google.guava</groupId>
<artifactId>guava</artifactId>
<version>22.0</version>
</dependency>
I also ran into this error and I never used Guava either. Funnily enough, my Glassfish server was using it's Guava version over the imported one! Run this code before the error to find out where your problematic Guava is coming from.
System.out.println(com.google.common.base.Preconditions.class.getProtectionDomain().getCodeSource().getLocation().toExternalForm());
Then download the most recent guava (currently Guava 22.0) and replace the old Guava file with the new one. This should fix your issue.
At this point, you should also be using the newer firebase version as well. I believe the developer also had the wrong Guava version in a previous firebase version.
<dependency>
<groupId>com.google.firebase</groupId>
<artifactId>firebase-admin</artifactId>
<version>5.2.0</version>
</dependency>
来源：https://stackoverflow.com/questions/44170175/nosuchmethoderror-while-integrating-firebase-with-app-engine-app