如何防止 android 应用崩溃

Question

我想阻止我的应用程序因未捕获的异常而崩溃。我希望将异常存储在日志中并防止应用程序崩溃。我如何实现这一目标？提前致谢。

Answer 1

您可以使用 try catch 块来捕获异常，这样可以防止您的应用程序崩溃。在 catch 块中获取预期的异常并将其记录下来以供您帮助。 但请记住，并非所有异常都可以被捕获 因为有些异常不是从 Exception 派生的 - 例如可抛出和错误。

基本上类型层次结构是：

   Object
     |
  Throwable
   /       \
Exception  Error

只能抛出 Throwable 和派生的类，所以如果你捕获 Throwable，那真的会捕获所有东西。

任何从 Exception（或 Exception 本身）派生的异常，而不是从 RuntimeException 派生的异常都算作已检查的异常 - 它们是您必须声明将抛出的异常，或者如果您调用抛出它们的东西则捕获的异常.

总而言之，Java 异常层次结构有点乱...

Answer 2

你可以自己处理未捕获的异常。在您的应用程序中使用以下代码 class.

public class MyApplication extends Application {
    private UncaughtExceptionHandler defaultUEH;

    private Thread.UncaughtExceptionHandler _unCaughtExceptionHandler =
        new Thread.UncaughtExceptionHandler() {
            @Override
            public void uncaughtException(Thread thread, Throwable ex) {

                // here I do logging of exception to a db
                Log.d("MyApp", "Uncaught exception.");     
               // Do what you want.

              // re-throw exception to O.S. if that is serious and need to be handled by o.s. Uncomment the next line that time.
            //defaultUEH.uncaughtException(thread, ex);
            }
        };

    public MyApplication() {
        defaultUEH = Thread.getDefaultUncaughtExceptionHandler();

        // setup Thread.setDefaultUncaughtExceptionHandler(_unCaughtExceptionHandler);
    }
}

Answer 3

为此，您只需要两个 classes 只需复制粘贴即可。当您的应用程序中发生任何异常时，将调用此 class。

public class CrashHandler implements
        java.lang.Thread.UncaughtExceptionHandler {
    private final Context myContext;
    private final String LINE_SEPARATOR = "\n";

    public CrashHandler(Context context) {
        myContext = context;
    }

    public void uncaughtException(Thread thread, Throwable exception) {
        StringWriter stackTrace = new StringWriter();
        exception.printStackTrace(new PrintWriter(stackTrace));
        StringBuilder errorReport = new StringBuilder();
        errorReport.append("************ CAUSE OF ERROR ************\n\n");
        errorReport.append(stackTrace.toString());

        errorReport.append("\n************ DEVICE INFORMATION ***********\n");
        errorReport.append("Brand: ");
        errorReport.append(Build.BRAND);
        errorReport.append(LINE_SEPARATOR);
        errorReport.append("Device: ");
        errorReport.append(Build.DEVICE);
        errorReport.append(LINE_SEPARATOR);
        errorReport.append("Model: ");
        errorReport.append(Build.MODEL);
        errorReport.append(LINE_SEPARATOR);
        errorReport.append("Id: ");
        errorReport.append(Build.ID);
        errorReport.append(LINE_SEPARATOR);
        errorReport.append("Product: ");
        errorReport.append(Build.PRODUCT);
        errorReport.append(LINE_SEPARATOR);
        errorReport.append("\n************ FIRMWARE ************\n");
        errorReport.append("SDK: ");
        errorReport.append(Build.VERSION.SDK);
        errorReport.append(LINE_SEPARATOR);
        errorReport.append("Release: ");
        errorReport.append(Build.VERSION.RELEASE);
        errorReport.append(LINE_SEPARATOR);
        errorReport.append("Incremental: ");
        errorReport.append(Build.VERSION.INCREMENTAL);
        errorReport.append(LINE_SEPARATOR);

        Intent intent = new Intent(myContext, ExceptionDisplay.class);
        intent.putExtra("error", errorReport.toString());
        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
        myContext.startActivity(intent);

        android.os.Process.killProcess(android.os.Process.myPid());
        System.exit(10);
    }

}

现在制作一个显示错误的 Activity :-

public class ExceptionDisplay extends AppCompatActivity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.exception_display_layout);

        TextView exception_text = (TextView) findViewById(R.id.exception_text);
        Button btnBack = (Button) findViewById(R.id.btnBack);
        exception_text.setText(getIntent().getExtras().getString("error"));

        btnBack.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                intentData();
            }
        });
    }

    @Override
    public void onBackPressed() {
        intentData();
    }

    public void intentData() {

        Log.d("CDA", "onBackPressed Called");
        Intent setIntent = new Intent(ExceptionDisplay.this, AppDataSourceSelection.class);
        setIntent.addCategory(Intent.CATEGORY_HOME);
        setIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        startActivity(setIntent);
    }
}

现在您可以通过扩展应用程序 Class 的 class 调用此 class:

public class ErrorHandler extends Application {


    @Override
    public void onCreate() {
        super.onCreate();
       Thread.setDefaultUncaughtExceptionHandler(new CrashHandler(getApplicationContext()));

        }}

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