Dialog基础（在一个Activity中创建多个Dialog）

Android Dev-Guide 推荐重写Activity.onCreateDialog()方法来创建Dialog，这样Dialog就归属于这个Activity了。使用方法是这样的，Activity.showDialog()激发Activity.onCreateDialog()创建Dialog，然后显示之，便于多个Dialog的统一管理。注意，以后再用Activity.showDialog()显示同一个Dialog时，则不会调用Activity.onCreateDialog()，而是调用Activity.onPrepareDialog()，使用上一次显示Dialog时的状态。即 
    第一次：showDialog() -> onCreatedialog() 
    以后： showDialog() -> onPrepareDialog() 

        在示例代码中，分别用createExitDialog()，createListDialog()，createRadioDialog()，createCheckboxDialog()，创建4种Dialog，并在Activity中显示。示例代码如下：

public class ShowDialogActivity extends Activity {
    /** Called when the activity is first created. */
public static final String TAG = "ShowDialog";
public static final int ID_EXIT_DIALOG = 1;
public static final int ID_LIST_DIALOG = 2;
public static final int ID_RADIO_DIALOG = 3;
public static final int ID_CHECKBOX_DIALOG = 4;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        showDialog(ID_EXIT_DIALOG);
        showDialog(ID_LIST_DIALOG);
        showDialog(ID_RADIO_DIALOG);
        showDialog(ID_CHECKBOX_DIALOG);
    }  
    @Override
    protected Dialog onCreateDialog(int id) {
    // TODO Auto-generated method stub
    Dialog dialog = null;
    switch(id) {
    case ID_EXIT_DIALOG :
    dialog = createExitDialog();
    break;
    case ID_LIST_DIALOG :
    dialog = createListDialog();
    break;
    case ID_RADIO_DIALOG :
    dialog = createRadioDialog();
    break;
    case ID_CHECKBOX_DIALOG :
    dialog = createCheckboxDialog();
    break;
    default :
    break; }
    if (dialog != null) {
    Log.i(TAG, dialog.toString());
    } else {
    Log.i(TAG, "dialog = null");   }
    return dialog;    }    
    @Override
    protected void onPrepareDialog(int id, Dialog dialog) {
    // TODO Auto-generated method stub
    super.onPrepareDialog(id, dialog);
    }
    //创建简单Dialog
    public Dialog createExitDialog() {
    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setMessage("Are you sure you want to exit?")
          .setCancelable(false)
          .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
              public void onClick(DialogInterface dialog, int id) {
                   ShowDialogActivity.this.finish();
              }
          })
          .setNegativeButton("No", new DialogInterface.OnClickListener() {
              public void onClick(DialogInterface dialog, int id) {
                   dialog.cancel();
              }
          });
    return builder.create();
    }
    //创建ListDialog
    public Dialog createListDialog() {
    final CharSequence[] items = {"Red", "Green", "Blue"};
    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setTitle("Pick a color");
    builder.setItems(items, new DialogInterface.OnClickListener() {
       public void onClick(DialogInterface dialog, int item) {
           Toast.makeText(getApplicationContext(), items[item], Toast.LENGTH_SHORT).show();
       }
    });
    return builder.create();
    }
    //创建单选Dialog
    public Dialog createRadioDialog() {
    final CharSequence[] items = {"Red", "Green", "Blue"};
    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setTitle("Pick a color");
    builder.setSingleChoiceItems(items, -1, new DialogInterface.OnClickListener() {
       public void onClick(DialogInterface dialog, int position) {
           Toast.makeText(getApplicationContext(), position + " -> " + items[position], Toast.LENGTH_SHORT).show();
           dialog.dismiss();
       }
    });
    return builder.create();
    }
    //创建多选Dialog
    public Dialog createCheckboxDialog() {
    final CharSequence[] items = {"Red", "Green", "Blue"};
    final boolean [] checked = new boolean [] {false, false, false};
   
    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setTitle("Pick a color");
    builder.setMultiChoiceItems(items, checked, new DialogInterface.OnMultiChoiceClickListener() {
@Override
public void onClick(DialogInterface dialog, int which, boolean isChecked) {
// TODO Auto-generated method stub
}
});
    builder.setPositiveButton("确定", new DialogInterface.OnClickListener() {
          public void onClick(DialogInterface dialog, int id) {
               ShowDialogActivity.this.finish();
          }
      })
      .setNegativeButton("取消", new DialogInterface.OnClickListener() {
          public void onClick(DialogInterface dialog, int id) {
               dialog.cancel();
          }
      });
    return builder.create();
    }
}