在一个Activity中使用多个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： 

 package com.ipjmc.dialog;

 import android.app.Activity;
 import android.app.AlertDialog;
 import android.app.Dialog;
 import android.content.DialogInterface;
 import android.os.Bundle;
 import android.util.Log;
 import android.widget.Toast;

 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();

     }
 }