Question

我有一个类来显示HTTP的错误消息。

根据throwable，它会显示一条消息。

但是有一段时间我得到空指针异常

public static void showGeneralErrors(Throwable throwable) {
    String message = "";
    AppInitialization appInitialization = AppInitialization.getInstance();

    if (appInitialization == null) {
        return;
    }

    try {
        if (throwable instanceof HttpException) {
            if (((HttpException) throwable).code() == 500) {
                message = appInitialization.getString(R.string.server_error);
            } else {
                message = appInitialization.getString(R.string.parsing_problem);
            }
        } else if (throwable instanceof IOException) {
            message = appInitialization.getString(R.string.internet_error);
        }else if(throwable instanceof SSLHandshakeException){
            message = appInitialization.getString(R.string.internet_error);
        }
        if (!TextUtils.isEmpty(message)) {
            Toast.makeText(appInitialization, message, Toast.LENGTH_SHORT).show();
        }
    } catch (Exception e) {
        Log.e(">>>>>", "Exception network error handler " + e.getMessage());
    } catch (IllegalStateException e) {
        Log.e(">>>>>", "IllegalStateException network error handler " + e.getMessage());
    } catch (NullPointerException e) {
        Log.e(">>>>>", "NullPointerException network error handler " + e.getMessage());
    }
}

错误信息是：

引起：java.lang.NullPointerException：尝试调用虚方法＆＃39; android.content.res.Resources android.content.Context.getResources（）＆＃39;在null对象引用上在android.widget.Toast.makeText（Toast.java:298）

公共AppInitialization是：

public class AppInitialization extends Application {
private static AppInitialization mInstance;

public static synchronized AppInitialization getInstance() {
    return mInstance;
}

public void onCreate() {
    super.onCreate();

    mInstance = this;
}

它来自改造Onfailure方法：

GeneralRepo.getCountryFromIp(getContext())
.observeOn(AndroidSchedulers.mainThread())
.subscribeOn(Schedulers.io())
.subscribe(countryFromIPResponse -> {
        //do something
    }, throwable -> {
        // Where i got error
        NetworkErrorHandler.showGeneralErrors(throwable);
    });

为什么我收到此错误以及为什么尝试/捕获不起作用？

Answer 1

将try catch块放在else部分，因为发生NullPointerException

appInitialization

即将为空......

写道：

public static void showGeneralErrors（Throwable throwable）{ 字符串消息=＆＃34;＆＃34 ;; AppInitialization appInitialization = AppInitialization.getInstance（）;
if (appInitialization == null) {
    return;
}else{

  try {           if (throwable instanceof HttpException) {
          if (((HttpException) throwable).code() == 500) {
              message = appInitialization.getString(R.string.server_error);
          } else {
              message = appInitialization.getString(R.string.parsing_problem);
          }           } else if (throwable instanceof IOException) {
          message = appInitialization.getString(R.string.internet_error);             }else if(throwable instanceof SSLHandshakeException){
          message = appInitialization.getString(R.string.internet_error);             }           if (!TextUtils.isEmpty(message)) {
          Toast.makeText(appInitialization, message, Toast.LENGTH_SHORT).show();          }       } catch (Exception e) {
      Log.e(">>>>>", "Exception network error handler " +
e.getMessage（））; } catch（IllegalStateException e）{ Log.e（＆＃34;＆gt;＆gt;＆gt;＆gt;＆gt;＆＃34;，＆＃34; IllegalStateException网络错误处理程序＆＃34; + e.getMessage（））; } catch（NullPointerException e）{ Log.e（＆＃34;＆gt;＆gt;＆gt;＆gt;＆gt;＆＃34;，＆＃34; NullPointerException网络错误处理程序＆＃34; + e.getMessage（））; }}

尝试/捕捉不起作用

1 个答案: