強制用戶在對話框中選擇選項

Question

第一次啓動應用程序時，我想提示用戶（通過對話框）選擇他們的城市，然後保存他們的偏好並將適當的數據加載到列表視圖中。但是，我注意到可以通過後退按鈕關閉對話框，或者向對話框外部的任何位置推入對話框，然後觸發數據庫的空值。

是否有反正我可以強制對話框保持打開，直到用戶選擇了一個選項？我已經實施了.setCancelable(false)，這似乎不起作用。我的代碼如下，DialogSetup是我正在使用的內部類。

任何幫助/想法，將不勝感激。

public class MainActivity extends ListActivity { 
private Cursor lines; 
private MetroSleepDb db; 
private ListAdapter adapter; 
public static final String PREFS_NAME = "METROSLEEP_PREFS"; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 


    super.onCreate(savedInstanceState); 



    chooseCityDialog(); 




} 




public void setAdapters() { 

    db = new MetroSleepDb(this); 
    lines = db.getLines(); // you would not typically call this on the main thread 
    //ListView listView = (ListView) findViewById(R.id.li); 
    adapter = new SimpleCursorAdapter(this, android.R.layout.simple_list_item_1, 
      lines, 
      new String[] {"line_id"}, 
      new int[] {android.R.id.text1}, 0); 


    getListView().setAdapter(adapter); 
    getListView().setOnItemClickListener(onAnswerClicked); 

} 


public String getItem(int pos) { 

    Cursor c = (Cursor) adapter.getItem(pos); 
    String value = c.getString(c.getColumnIndex("line_id")); 
    return value; 
} 

private OnItemClickListener onAnswerClicked = new OnItemClickListener() { 
    @Override 
    public void onItemClick(AdapterView<?> parent, View view, int position, 
      long id) { 

     String line_value = getItem(position); 
     Intent intent = new Intent(MainActivity.this, ChooseStations.class); 
     intent.putExtra("line", line_value); 
     startActivity(intent); 
    } 

}; 

@Override 
public boolean onCreateOptionsMenu(Menu menu) { 
    // Inflate the menu; this adds items to the action bar if it is present. 
    getMenuInflater().inflate(R.menu.activity_main, menu); 
    return true; 
} 


@Override 
public boolean onOptionsItemSelected(MenuItem item) { 
    switch (item.getItemId()) { 
    case android.R.id.home: 
     // This ID represents the Home or Up button. In the case of this 
     // activity, the Up button is shown. Use NavUtils to allow users 
     // to navigate up one level in the application structure. For 
     // more details, see the Navigation pattern on Android Design: 
     // 
     // http://developer.android.com/design/patterns/navigation.html#up-vs-back 
     // 
     NavUtils.navigateUpFromSameTask(this); 
     return true; 

    case R.id.menu_settings: 
     Intent intent = new Intent(this, SettingsActivity.class); 
     startActivity(intent); 
     return true; 
    } 
    return super.onOptionsItemSelected(item); 
} 

public void chooseCityDialog() { 
    DialogFragment newFragment = new DialogSetup(); 
    newFragment.show(getFragmentManager(), "citypref"); 
} 

public static final class DialogSetup extends DialogFragment { 
    public Dialog onCreateDialog(Bundle savedInstanceState) { 

     AlertDialog.Builder builder = new AlertDialog.Builder(getActivity()); 
     builder.setTitle(R.string.prompt_choose_city) 
       .setCancelable(false) 
       .setItems(R.array.Cities, new DialogInterface.OnClickListener() { 
        public void onClick(DialogInterface dialog, int which) { 
         // 
       } 
     }); 

     return builder.create(); 
    } 



} 

}

Answer 1

啊哈禁用後退按鈕！您必須撥打DialogFragment上的setCancelable(false)，而不是AlertDialog.builder。看到這個問題：AlertDialog's setCancelable(false) method not working。

的文檔DialogFragment.setCancelable(boolean cancelable)狀態：

控制所示的對話框是否取消。使用它而不是直接調用Dialog.setCancelable（boolean），因爲DialogFragment需要根據這個來改變它的行爲。

你只需要加1行代碼：

public void chooseCityDialog() { 
    DialogFragment newFragment = new DialogSetup(); 
    newFragment.setCancelable(false); 
    newFragment.show(getFragmentManager(), "citypref"); 
} 

而且，這將是一個很好的安全檢查，有一個默認的城市回落到，如果以某種方式從城市Dialog返回是null。

Answer 2

我只想用一個AlertDialog，而不是DialogFragment這一點。

AlertDialog dlgBuilder = new AlertDialog.Builder(this); 
    dlgBuilder.setMessage("Title"); 
    dlgBuilder.setCancelable(false) 
      .setPositiveButton("OK", new OnClickListener() { 
       @Override 
       public void onClick(DialogInterface dialogInterface, int i) { 
        okCalledMethodInactivity(); 
        dialogInterface.dismiss(); 
       } 
      }) 
      .setNegativeButton("Exit app", new OnClickListener() { 
       @Override 
       public void onClick(DialogInterface dialogInterface, int i) { 
        finish(); 
       } 
      }); 
    AlertDialog dlg = dlgBuilder.create(); 
    dlg.show(); 

Answer 3

通過

@Override 
public void onBackPressed() { 

}