Question

我一直在创建一个应用程序，基于目标sdk版本15，最小sdk版本为8.当我在运行版本8的设备上运行它时，每个东西都运行得很完美。但是当我在高于版本的任何东西上尝试它时10它与NullPointerException崩溃。

logcat给了我这个：

10-06 19:23:12.927: E/AndroidRuntime(589): FATAL EXCEPTION: main
10-06 19:23:12.927: E/AndroidRuntime(589): java.lang.RuntimeException: Unable to start                 activity        ComponentInfo{com.fansheroid.facts.chicks/com.fansheroid.facts.chicks.MainActivity}:   java.lang.NullPointerException
10-06 19:23:12.927: E/AndroidRuntime(589):  at     android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1955)
10-06 19:23:12.927: E/AndroidRuntime(589):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1980)
10-06 19:23:12.927: E/AndroidRuntime(589):  at android.app.ActivityThread.access$600(ActivityThread.java:122)
10-06 19:23:12.927: E/AndroidRuntime(589):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1146)
10-06 19:23:12.927: E/AndroidRuntime(589):  at android.os.Handler.dispatchMessage(Handler.java:99)
10-06 19:23:12.927: E/AndroidRuntime(589):  at android.os.Looper.loop(Looper.java:137)
10-06 19:23:12.927: E/AndroidRuntime(589):  at android.app.ActivityThread.main(ActivityThread.java:4340)
10-06 19:23:12.927: E/AndroidRuntime(589):  at java.lang.reflect.Method.invokeNative(Native Method)
10-06 19:23:12.927: E/AndroidRuntime(589):  at java.lang.reflect.Method.invoke(Method.java:511)
10-06 19:23:12.927: E/AndroidRuntime(589):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
10-06 19:23:12.927: E/AndroidRuntime(589):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
10-06 19:23:12.927: E/AndroidRuntime(589):  at dalvik.system.NativeStart.main(Native Method)
10-06 19:23:12.927: E/AndroidRuntime(589): Caused by: java.lang.NullPointerException
10-06 19:23:12.927: E/AndroidRuntime(589):  at org.json.JSONTokener.nextCleanInternal(JSONTokener.java:116)
10-06 19:23:12.927: E/AndroidRuntime(589):  at org.json.JSONTokener.nextValue(JSONTokener.java:94)
10-06 19:23:12.927: E/AndroidRuntime(589):  at org.json.JSONObject.<init>(JSONObject.java:154)
10-06 19:23:12.927: E/AndroidRuntime(589):  at org.json.JSONObject.<init>(JSONObject.java:171)
10-06 19:23:12.927: E/AndroidRuntime(589):  at com.fansheroid.facts.chicks.MainActivity.getTumblrs(MainActivity.java:156)
10-06 19:23:12.927: E/AndroidRuntime(589):  at com.fansheroid.facts.chicks.MainActivity.onCreate(MainActivity.java:62)
10-06 19:23:12.927: E/AndroidRuntime(589):  at android.app.Activity.performCreate(Activity.java:4465)
10-06 19:23:12.927: E/AndroidRuntime(589):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
10-06 19:23:12.927: E/AndroidRuntime(589):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1919)
10-06 19:23:12.927: E/AndroidRuntime(589):  ... 11 more

过去两天我一直试图弄清楚这个问题，但这对我来说没有意义。

编辑添加代码

public ArrayList<Tumblr> getTumblrs() throws ClientProtocolException,
        IOException, JSONException {
    String searchUrl = "http://api.tumblr.com/v2/blog/factsandchicks.com/posts?api_key=API_KEY";

    ArrayList<Tumblr> tumblrs = new ArrayList<Tumblr>();

    HttpClient client = new DefaultHttpClient();
    HttpGet get = new HttpGet(searchUrl);

    ResponseHandler<String> responseHandler = new BasicResponseHandler();

    String responseBody = null;
    try {
        responseBody = client.execute(get, responseHandler);
    } catch (Exception ex) {
        ex.printStackTrace();
    }

    JSONObject jsonObject = new JSONObject(responseBody);

    JSONArray posts = jsonObject.getJSONObject("response").getJSONArray(
            "posts");
    for (int i = 0; i < posts.length(); i++) {
        JSONArray photos = posts.getJSONObject(i).getJSONArray("photos");
        for (int j = 0; j < photos.length(); j++) {
            JSONObject photo = photos.getJSONObject(j);
            String url = photo.getJSONArray("alt_sizes").getJSONObject(0)
                    .getString("url");

            Tumblr tumblr = new Tumblr(url);
            tumblrs.add(tumblr);
        }
    }
    return tumblrs;
}

第156行：

JSONObject jsonObject = new JSONObject(responseBody);

Answer 1

啊，看看这个：

E/AndroidRuntime(589): Caused by: java.lang.NullPointerException 10-06 19:23:12.927: 
E/AndroidRuntime(589): at org.json.JSONTokener.nextCleanInternal(JSONTokener.java:116) 10-06 19:23:12.927:
E/AndroidRuntime(589): at org.json.JSONTokener.nextValue(JSONTokener.java:94) 10-06 19:23:12.927:
E/AndroidRuntime(589): at org.json.JSONObject.(JSONObject.java:154) 10-06 19:23:12.927: 
E/AndroidRuntime(589): at org.json.JSONObject.(JSONObject.java:171) 10-06 19:23:12.927: 
E/AndroidRuntime(589): at com.fansheroid.facts.chicks.MainActivity.getTumblrs(MainActivity.java:156) 10-06 19:23:12.927: 
E/AndroidRuntime(589): at com.fansheroid.facts.chicks.MainActivity.onCreate(MainActivity.java:62)

它基本上说JSON解析器失败了：你可能在MainActivity.java的第156行传递NULL。您应检查该行的值，看看您的设备升级是否以某种方式消除了值或无法正确检索值。

Answer 2

try {
    responseBody = client.execute(get, responseHandler);
} catch (Exception ex) {
    ex.printStackTrace();
}

该部分代码是您的响应失败的地方。你为响应体分配了null，很可能你的调用失败了，因此当响应第156行时，responsebody仍为null。

尝试查看ex.printStackTrace（）的调试输出;输出以查看正在发生的事情。

Answer 3

通过使用HttpResponse和HttpEntity而不是ResponseHandler来解决问题，这解决了这个问题。

应用程序在更高版本的Android上崩溃

3 个答案: