意向不從片段開始活動

Question

我在Android片段中產生強度問題。 我有一個活動，其中包含一個片段，而該片段又包含一個ListView。 我已經將onItemClickListener注冊到ListView，當我在Activity中擁有listView時，此方法運行良好。 我需要將其包裝在片段中。

因此，現在不再調用getContext()而不是調用getActivity()因為在任何地方都建議這樣做。 實際上，這確實返回了正確的Activity。 點擊也被注冊，因為我的LogCat正在打印。 但是意圖永遠不會開始。 什么都沒發生。 誰能告訴我我想念的東西嗎？

這是我的代碼：

_dealList.setOnItemClickListener(new AdapterView.OnItemClickListener()
        {
            @Override
            public void onItemClick(AdapterView<?> parent, View v, int position, long id)
            {
                Intent in = new Intent(getActivity(), DealView.class);
                in.putExtra("deal", position);
                in.putExtra("city", _citySearchBar.getText());
                startActivity(in);
                Log.d("BASE_FRAGMENT", "Activity should have been started here");
            }
        });
    }

該代碼位於抽象類內部，但將其移至子類不會產生任何影響。

目的是針對以下DealView類：

public class DealView extends AppCompatActivity {
    private TextView _priceView;
    private TextView _descriptionView;
    private TextView _titleView;
    private TextView _storeView;
    private ImageView _imageView;
    private String _cityName;

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

            Intent fromDealSelection = getIntent();
            _cityName = fromDealSelection.getStringExtra("city");

            //Initializing the different components of the view
            _priceView = (TextView) findViewById(R.id.priceInputDealView);

            _descriptionView = (TextView) findViewById(R.id.dealDescriptionDealView);

            _titleView = (TextView) findViewById(R.id.dealTitleDealView);

            _storeView = (TextView) findViewById(R.id.storeDealView);

            _imageView = (ImageView) findViewById(R.id.imageViewDealView);

            _cityName = fromDealSelection.getStringExtra("city");

        }

這是LogCat的輸出：

03/01 09:42:23: Launching app
W/System: ClassLoader referenced unknown path: /data/data/de.coding.mb.konstisapp/lib
Hot swapped changes, activity restarted
D/BASE_FRAGMENT: Activity should have been started here
D/BASE_FRAGMENT: Activity should have been started here

這是我的AndroidManifest.xml文件：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
          package="de.coding.mb.konstisapp">

    <uses-feature
        android:name="android.hardware.camera"
        android:required="false"/>

    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
    <uses-permission
        android:name="android.permission.WRITE_EXTERNAL_STORAGE"
        android:maxSdkVersion="18"/>
    <uses-permission android:name="android.permission.INTERNET"/>

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".activities.GreatingsActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>

                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>
        <activity
            android:name=".activities.DealSelectionActivity"
            android:label="@string/title_activity_deal_selection"
            android:parentActivityName=".activities.GreatingsActivity"
            android:theme="@style/AppTheme.NoActionBar">
            <meta-data
                android:name="android.support.PARENT_ACTIVITY"
                android:value="de.coding.mb.konstisapp.activities.GreatingsActivity"/>
        </activity>
        <activity
            android:name=".activities.DealCreationActivity"
            android:label="@string/title_activity_activity_deal_creation"
            android:parentActivityName=".activities.DealSelectionActivity"
            android:theme="@style/AppTheme.NoActionBar">
            <meta-data
                android:name="android.support.PARENT_ACTIVITY"
                android:value="de.coding.mb.konstisapp.activities.DealSelectionActivity"/>
        </activity>
        <activity android:name=".activities.DealView"
                  android:label="@string/title_activity_deal_view"
                  android:parentActivityName=".activities.DealSelectionActivity"
                  android:theme="@style/AppTheme.NoActionBar">
            <meta-data
                android:name="android.support.PARENT_ACTIVITY"
                android:value="de.coding.mb.konstisapp.activities.DealSelectionActivity">

            </meta-data>
        </activity>
</manifest>

Answer 1

由於無法從Fragment中啟動新的Activity，因此您可以嘗試將代碼遷移到托管Activity。 一種干凈且可重用的方法是在新文件中創建接口。

public interface myInterface {
    public void startMyIntent(Intent i);
}

然后，在Activity類中實現此接口，托管您的Fragment

public class hostingActivity extends AppCompatActivity implements myInterface {
    @Override
    public void startMyIntent(Intent i) {
        startActivity(i);
    }
}

在您片段的onItemClickListener ，您可以像這樣調用它

_dealList.setOnItemClickListener(new AdapterView.OnItemClickListener()
    {
        @Override
        public void onItemClick(AdapterView<?> parent, View v, int position, long id)
        {
            Activity parentActivity = getActivity();
            Intent in = new Intent(parentActivity, DealView.class);
            in.putExtra("deal", position);
            in.putExtra("city", _citySearchBar.getText());
            ((myInterface)parentActivity).startMyIntent(in);
            Log.d("BASE_FRAGMENT", "Activity should have been started here");
        }
    });
}

Answer 2

從片段內部，您不能只使用startActivity()
您必須使用getActivity().startActivity(in)

_dealList.setOnItemClickListener(new AdapterView.OnItemClickListener()
    {
        @Override
        public void onItemClick(AdapterView<?> parent, View v, int position, long id)
        {
            Intent in = new Intent(getActivity(), DealView.class);
            in.putExtra("deal", position);
            in.putExtra("city", _citySearchBar.getText());
            getActivity().startActivity(in);
            Log.d("BASE_FRAGMENT", "Activity should have been started here");
        }
    });
}

另請參閱如何從片段內開始活動？

Answer 3

修改密碼

_dealList.setOnItemClickListener(new AdapterView.OnItemClickListener()
        {
           @Override
            public void onItemClick(AdapterView<?> parent, View v, int position, long id)
            {
                Intent in = new Intent(v.getContext(), DealView.class);
                in.putExtra("deal", position);
                in.putExtra("city", _citySearchBar.getText());
                startActivity(in);
                Log.d("BASE_FRAGMENT", "Activity should have been started here");
            }
        });
    }

Answer 4

在intent.setFlags（...）方法中使用FLAG_ACTIVITY_NEW_TASK。

_dealList.setOnItemClickListener(new AdapterView.OnItemClickListener()
    {
       @Override
        public void onItemClick(AdapterView<?> parent, View v, int position, long id)
        {
            Intent in = new Intent(v.getContext(), DealView.class);
            in.putExtra("deal", position);
            in.putExtra("city", _citySearchBar.getText());
            in.setFlag(Acitvity.FLAG_ACTIVITY_NEW_TASK);
            getActivity().startActivity(in);
            Log.d("BASE_FRAGMENT", "Activity should have been started here");
        }
    });
}