从两个不同的活动中调用函数显示警报对话框

时间：2015-11-05 08:33:05

标签： android alertdialog android-alertdialog applicationcontext

我遇到了一种情况，即我的两个活动应该调用相同的功能。 MainActivity和SMSActivity。我编写了一个HelperClass并创建了一个函数getTagSelectionFromDialogBox（）。 getTagSelectionFromDialogBox（）显示警告对话框并完成一些工作。

我正在从MainActivity实例化HelperClass并通过传递上下文调用helperclass.getTagSelectionFromDialogBox（）工作正常。

但是当我从SMSActivity执行相同操作时，应用程序崩溃了。我认为这是因为错误的背景但不确定。

当启动HelperClass（）时，我从MainActivity调用HelperClass.getinstance（getApplicationContext（）），当从SMSActivity执行时，我调用HelperClass.getinstalce（getApplicationContext（））。

以下是MainActivity的代码

#include <iostream>
#include <string>
#include <cstdlib>
#include <boost/interprocess/ipc/message_queue.hpp>
#include <boost/scoped_ptr.hpp>
#include <boost/interprocess/shared_memory_object.hpp>
#include <boost/interprocess/managed_shared_memory.hpp>
#include <boost/interprocess/mapped_region.hpp>
#include <boost/interprocess/allocators/allocator.hpp>
#include <boost/interprocess/containers/string.hpp>
#include <boost/interprocess/containers/vector.hpp>
#include <boost/shared_array.hpp>
#include <boost/interprocess/containers/list.hpp>
#include <boost/version.hpp>

using namespace boost::interprocess;


struct InData;
typedef boost::interprocess::allocator<InData, managed_shared_memory::segment_manager> salloc;
typedef boost::interprocess::basic_string<char, std::char_traits<char>, salloc::rebind<char>::other> shared_string;
typedef boost::interprocess::vector<float, salloc::rebind<float>::other> shared_float_vec;

struct InData {
    int X, Y, H, W;

    InData(salloc alloc) : Label(alloc), Floats(alloc) {}
    shared_string Label;
    shared_float_vec Floats;
};

int main() {

    std::cout << "Using Boost "
              << BOOST_VERSION / 100000     << "."  // major version
              << BOOST_VERSION / 100 % 1000 << "."  // minor version
              << BOOST_VERSION % 100                // patch level
              << std::endl;

    shared_memory_object::remove("MySharedMemory");
    managed_shared_memory managed_shm(create_only, "MySharedMemory", 10000);

    salloc alloc_inst(managed_shm.get_segment_manager());

    InData tData(alloc_inst); // = managed_shm.construct<InData>("InDataStructure")();

    tData.Label = "Hello World";
    tData.Floats.push_back(3.14);
    tData.H = 1;
    tData.W = 1;
    tData.Y = 1;
    tData.X = 1;

    typedef boost::interprocess::list<InData, salloc> MyList;
    MyList *myvector = managed_shm.construct<MyList>("MyVector")(alloc_inst);

    myvector->push_back(tData);
}

来自SMSActivity 

    HelperClass helperclass = HelperClass.getInstalce(getApplicationContext());
    tagHandler.getTagSelectionFromDialogBox(rowData);

HelperClass代码的一部分是

    HelperClass helperclass = HelperClass.getInstalce(getApplicationContext());
    helperclass.getTagSelectionFromDialogBox(rowData);

}

Logcat显示以下错误

    public class HelperClass {

Context context = null;
private static HelperClass HelperClass = null;

private HelperClass(Context context) {
    this.context = context;

}

public static synchronized HelperClass getInstalce(Context context) {
    if(helperclass == null) {
        helperclass = new TagHandler(context.getApplicationContext());
    }

    return helperclass;
}

public  void getTagSelectionFromDialogBox(final RowData rowData) {
    String selectedTitle = null;
String[] navTitles = = {"one", "tow", "Three"};

    AlertDialog.Builder alertDialog = new AlertDialog.Builder(context.getApplicationContext());
    alertDialog.setTitle("Select Category");
    alertDialog.setSingleChoiceItems(navTitles, -1, new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {
            int title_position = which;
            String selectedTitle = navTitles[which];
            dialog.cancel();
            if (rowData.getInfoPath() != null) {
                //doing some work
            } else {
                //doing some work
            }
        }
    });
    AlertDialog ad = alertDialog.create();
    ad.show();
}

其中HelperClass.java:75是ad.show（）。我怀疑问题可能是通过上下文但不确定如何解决问题。

MainActivity代码部分。它是巨大的，所以把它的onCate（）代码：

        android.view.WindowManager$BadTokenException: Unable to add window -- token null is not for an application
        at android.view.ViewRootImpl.setView(ViewRootImpl.java:570)
        at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:282)
        at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:85)
        at android.app.Dialog.show(Dialog.java:306)
        at com.srids.tagit.TagHandler.getTagSelectionFromDialogBox(HelperClass.java:75)
        at com.srids.tagit.SMSActivity$2.onClick(SMSActivity.java:140)
        at android.view.View.performClick(View.java:4856)
        at android.view.View$PerformClick.run(View.java:19956)
        at android.os.Handler.handleCallback(Handler.java:739)
        at android.os.Handler.dispatchMessage(Handler.java:95)

}

}

3 个答案:

答案 0 :(得分：1)

您所做的并不是处理此类情况的正确方法更新您的代码 

  public class HelperClass {

    public static void getTagSelectionFromDialogBox(final Context context,final RowData rowData) {
        String selectedTitle = null;
    String[] navTitles = = {"one", "tow", "Three"};

        AlertDialog.Builder alertDialog = new AlertDialog.Builder(context);
        alertDialog.setTitle("Select Category");
        alertDialog.setSingleChoiceItems(navTitles, -1, new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                int title_position = which;
                String selectedTitle = navTitles[which];
                dialog.cancel();
                if (rowData.getInfoPath() != null) {
                    //doing some work
                } else {
                    //doing some work
                }
            }
        });
        AlertDialog ad = alertDialog.create();
        ad.show();
    }

    }

用法 

HelperClass.getTagSelectionFromDialogBox(MainActivty.this,rowData);

用下面的

替换MainActivity代码 
    public class MainActivity extends ActionBarActivity implements NavigationDrawerFragment.FragmentDrawerListener, shareDataInterface {

private Toolbar toolbar;
NavigationDrawerFragment navigationDrawerFragment;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    toolbar = (Toolbar) findViewById(R.id.toolbar);
    toolbar.setTitle("tagIt");
    toolbar.setSubtitle("make search easy..");
    toolbar.setTitleTextColor(getResources().getColor(R.color.colorAccent));
    setSupportActionBar(toolbar);
    getSupportActionBar().setDisplayShowHomeEnabled(true);

    utils= new Utils();
    prefs = MyPrefs.getInstance(this);
    if(prefs.getBool(MyGlobals.PASSWORD_PROTECT) == true) {
        if(loggedin == 0) {
            loggedin = 1;
            utils.showDialog(MainActivity.this, MyGlobals.DIALOG_PIN_INPUT);
        }
    }

    // populate navigation drawer
    navigationDrawerFragment = (NavigationDrawerFragment) getSupportFragmentManager().findFragmentById(R.id.fragment_navigation_drawer);
    navigationDrawerFragment.setUp(R.id.fragment_navigation_drawer, (DrawerLayout) findViewById(R.id.drawer_layout), toolbar);
    navigationDrawerFragment.setDrawerListener(this);

    // establish data base connection and first read tags list for NAV drawer
    db = DatabaseHelper.getInstance(getApplicationContext());

    navTitles =navigationDrawerFragment.titles;

 //Get your rowdata before calling the method

  HelperClass.getTagSelectionFromDialogBox(MainActivty.this,rowData);

答案 1 :(得分：1)

您不应该使用应用程序上下文来显示对话框而不是活动。没有视图用于附加到应用程序Context的对话框。如果要在MainActivity和SMSActivity上显示两个对话框，则需要更新HelperClass类中的上下文值。

也许你可以改变你的代码：

MainActivity 

HelperClass helperclass = HelperClass.getInstalce();
helperclass .getTagSelectionFromDialogBox(MainActivity.this, rowData);

SMSActivity 

HelperClass helperclass = HelperClass.getInstalce();
helperclass .getTagSelectionFromDialogBox(SMSActivity.this, rowData);

HelperClass 

public class HelperClass {

private static HelperClass helperclass = null;

private HelperClass() {

}

public static synchronized HelperClass getInstalce() {
    if (helperclass == null) {
        helperclass = new HelperClass();
    }
    return helperclass;
}

public void getTagSelectionFromDialogBox(Context context, final RowData rowData) {
    String selectedTitle = null;
    String[] navTitles = {"one", "tow", "Three"};

    AlertDialog.Builder alertDialog = new AlertDialog.Builder(context);
    alertDialog.setTitle("Select Category");
    alertDialog.setSingleChoiceItems(navTitles, -1, new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {
            int title_position = which;
            String selectedTitle = navTitles[which];
            dialog.cancel();
            if (rowData.getInfoPath() != null) {
                //doing some work
            } else {
                //doing some work
            }
        }
    });
    AlertDialog ad = alertDialog.create();
    ad.show();
}

}

答案 2 :(得分：0)

除了anoop的答案之外，请执行此操作以获得更好的性能 如果您正在使用应用程序类，请将以下代码放在应用程序类中，

HelperClass mHelperClass;
public final HelperClass getHelperClass() {
    if(mHelperClass == null) {
        mHelperClass = new HelperClass();
    }
    return mHelperClass;
}

并在任何地方使用getHelperClass（）方法。

希望这可以帮到你..

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