Twitter4J - 使用getLatitude（）时出现空指针异常

时间：2014-03-29 19:16:24

标签： java json twitter jersey twitter4j

我正在尝试将推文的纬度和经度存储在JSON对象中。我只使用地理位置时工作正常。

离。 obj.put("coordinates", tweet.getGeoLocation());

当我改变它以获得纬度或经度时会抛出空指针异常。

离。 obj.put("lat", tweet.getGeoLocation().getLatitude());

代码：

JSONArray array = new JSONArray();
try {
        Query query = new Query("query");
        QueryResult result;
        result = twitter.search(query);
        tweets = result.getTweets();

    for (Status tweet : tweets) {

        JSONObject obj = new JSONObject();

        obj.put("userName", tweet.getUser().getScreenName());
        obj.put("text", tweet.getText());
        obj.put("lat", tweet.getGeoLocation().getLatitude());
        obj.put("lon", tweet.getGeoLocation().getLongitude());

        String json = obj.toString();
        array.put(obj);

    }
    System.out.println(array);
}
catch (TwitterException te) {
    te.printStackTrace();
    System.out.println("Failed to search tweets: " + te.getMessage());
    System.exit(-1);
  }
    return array;
}

这是错误：

SEVERE: Servlet.service() for servlet [Jersey REST Service] in context with path [/Jersey] threw exception java.lang.NullPointerException

更新：它现在似乎已经完成了一半，它现在确实获得了经度和经度，但仍然存在错误。 这是输出日志。

Mar 29, 2014 8:24:25 PM com.sun.jersey.spi.container.ContainerResponse mapMappableContainerException
SEVERE: The RuntimeException could not be mapped to a response, re-throwing to the HTTP container
java.lang.NullPointerException
    at sample.hello.resources.TweetUsingTwitter4jExample.getTweets(TweetUsingTwitter4jExample.java:70)
    at sample.hello.resources.HelloResource.sayHello(HelloResource.java:25)
    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:606)
    at com.sun.jersey.spi.container.JavaMethodInvokerFactory$1.invoke(JavaMethodInvokerFactory.java:60)
    at com.sun.jersey.server.impl.model.method.dispatch.AbstractResourceMethodDispatchProvider$TypeOutInvoker._dispatch(AbstractResourceMethodDispatchProvider.java:185)
    at com.sun.jersey.server.impl.model.method.dispatch.ResourceJavaMethodDispatcher.dispatch(ResourceJavaMethodDispatcher.java:75)
    at com.sun.jersey.server.impl.uri.rules.HttpMethodRule.accept(HttpMethodRule.java:302)
    at com.sun.jersey.server.impl.uri.rules.ResourceClassRule.accept(ResourceClassRule.java:108)
    at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:147)
    at com.sun.jersey.server.impl.uri.rules.RootResourceClassesRule.accept(RootResourceClassesRule.java:84)
    at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1542)
    at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1473)
    at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1419)
    at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1409)
    at com.sun.jersey.spi.container.servlet.WebComponent.service(WebComponent.java:409)
    at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:540)
    at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:715)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1041)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:603)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:744)

Mar 29, 2014 8:24:25 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [Jersey REST Service] in context with path [/Jersey] threw exception
java.lang.NullPointerException
    at sample.hello.resources.TweetUsingTwitter4jExample.getTweets(TweetUsingTwitter4jExample.java:70)
    at sample.hello.resources.HelloResource.sayHello(HelloResource.java:25)
    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:606)
    at com.sun.jersey.spi.container.JavaMethodInvokerFactory$1.invoke(JavaMethodInvokerFactory.java:60)
    at com.sun.jersey.server.impl.model.method.dispatch.AbstractResourceMethodDispatchProvider$TypeOutInvoker._dispatch(AbstractResourceMethodDispatchProvider.java:185)
    at com.sun.jersey.server.impl.model.method.dispatch.ResourceJavaMethodDispatcher.dispatch(ResourceJavaMethodDispatcher.java:75)
    at com.sun.jersey.server.impl.uri.rules.HttpMethodRule.accept(HttpMethodRule.java:302)
    at com.sun.jersey.server.impl.uri.rules.ResourceClassRule.accept(ResourceClassRule.java:108)
    at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:147)
    at com.sun.jersey.server.impl.uri.rules.RootResourceClassesRule.accept(RootResourceClassesRule.java:84)
    at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1542)
    at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1473)
    at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1419)
    at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1409)
    at com.sun.jersey.spi.container.servlet.WebComponent.service(WebComponent.java:409)
    at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:540)
    at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:715)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1041)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:603)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:744)

1 个答案:

答案 0 :(得分：0)

我认为发生的事情是，您正在收获的一些推文的地理位置元素是null。除非推文本身为null，否则没有任何其他内容可能抛出NullPointerException，但由于如果按原样存储GeoLocation元素而不提取经度，则不会出现异常，因此情况似乎并非如此和纬度。

另外，如果您检查getGeolocation()方法的javadoc，您会发现推文没有义务进行地理定位，因此位置可能是null：

   /**
     * Returns The location that this tweet refers to if available.
     *
     * @return returns The location that this tweet refers to if available (can be null)
     * @since Twitter4J 2.1.0
     */
    GeoLocation getGeoLocation();

我建议您执行以下操作，看看它是否解决了您的问题：

for (Status tweet : tweets) {

    JSONObject obj = new JSONObject();

    obj.put("userName", tweet.getUser().getScreenName());
    obj.put("text", tweet.getText());
    final GeoLocation location  = tweet.getGeolocation();
    if(location != null) {
       obj.put("lat", location().getLatitude());
       obj.put("lon", location().getLongitude());
    }
    String json = obj.toString();
    array.put(obj);
}
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