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();

    }
}