Android 程式開發：（一）詳解活動 —— 1.4 顯示普通對話框

有的時候，可能需要彈出一個對話框，以便從用戶的輸入來獲取某些確認信息。這種情況下，可以重寫Activity基類中的受保護方法（protected）onCreateDialog()。
1、創建一個工程：Dialog。
 
2、main.xml中的代碼。
 
<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="https://schemas.android.com/apk/res/android" 
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent" 
    android:orientation="vertical" > 
     
<Button 
    android:id="@+id/btn_dialog" 
    android:layout_width="fill_parent"  
    android:layout_height="wrap_content" 
    android:text="Click to display a dialog" 
    android:onClick="onClick" /> 
  
</LinearLayout> 
 
3、DialogActivity.java中的代碼。
 
package net.horsttnann.Dialog; 
 
import android.app.Activity; 
import android.app.AlertDialog; 
import android.app.Dialog; 
import android.content.DialogInterface; 
import android.os.Bundle; 
import android.view.View; 
import android.widget.Toast; 
 
public class DialogActivity extends Activity { 
    CharSequence[] items = { "Google", "Apple", "Microsoft" }; 
    boolean[] itemsChecked = new boolean[items.length]; 
 
    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
        super.onCreate(savedInstanceState); 
        setContentView(R.layout.main); 
    } 
 
    public void onClick(View v) { 
        showDialog(0); 
    } 
 
    @Override 
    protected Dialog onCreateDialog(int id) { 
        switch (id) { 
        case 0: 
            return new AlertDialog.Builder(this) 
                    .setIcon(R.drawable.ic_launcher) 
                    .setTitle("This is a dialog with some simple text…") 
                    .setPositiveButton("OK", 
                            new DialogInterface.OnClickListener() { 
                                public void onClick(DialogInterface dialog, 
                                        int whichButton) { 
                                    Toast.makeText(getBaseContext(), 
                                            "OK clicked!", Toast.LENGTH_SHORT) 
                                            .show(); 
                                } 
                            }) 
                    .setNegativeButton("Cancel", 
                            new DialogInterface.OnClickListener() { 
                                public void onClick(DialogInterface dialog, 
                                        int whichButton) { 
                                    Toast.makeText(getBaseContext(), 
                                            "Cancel clicked!", 
                                            Toast.LENGTH_SHORT).show(); 
                                } 
                            }) 
                    .setMultiChoiceItems(items, itemsChecked, 
                            new DialogInterface.OnMultiChoiceClickListener() { 
                                public void onClick(DialogInterface dialog, 
                                        int which, boolean isChecked) { 
                                    Toast.makeText( 
                                            getBaseContext(), 
                                            items[which] 
                                                    + (isChecked ? " checked!" 
                                                            : " unchecked!"), 
                                            Toast.LENGTH_SHORT).show(); 
 
                                } 
                            }).create(); 
        } 
        return null; 
    } 
} 
 
4、調試。
 
點擊按鈕彈出對話框，在CheckBox上面打勾，就會彈出一個Toast提示，顯示選中物件的文本信息。點擊“OK”或“Cancel”按鈕會使對話框消失。
 
 
 
 
 
 

 
 
 
想要顯示對話框，首先要重寫Activity基類中的onCreateDialog()方法：
 
@Override  www.aiwalls.com
protected Dialog onCreateDialog(int id) { 
    // … 
} 
當調用showDialog()的時候，上面被重寫的方法就被調用瞭：public void onClick(View v) { 
    showDialog(0); 
} 
這個創建對話框的onCreateDialog()方法是一個被Activity控制的回調函數，當調用showDialog()時，onCreateDialog()回調函數就被觸發瞭。showDialog()方法接受一個Integer參數，用來識別到底要顯示哪個對話框。一般情況下，使用switch語句去判斷顯示不同的對話框。
想要創建一個對話框，還需要使用AlertDialog類的Builder構造器，設置不同的屬性，比如圖標、標題、按鈕、單選框等等：
 
    @Override 
    protected Dialog onCreateDialog(int id) { 
        switch (id) { 
        case 0: 
            Builder builder = new AlertDialog.Builder(this); 
            builder.setIcon(R.drawable.ic_launcher); 
            builder.setTitle("This is a dialog with some simple text…"); 
            builder.setPositiveButton("OK", 
                    new DialogInterface.OnClickListener() { 
                        public void onClick(DialogInterface dialog, 
                                int whichButton) { 
                            Toast.makeText(getBaseContext(), "OK clicked!", 
                                    Toast.LENGTH_SHORT).show(); 
                        } 
                    }); 
 
            builder.setNegativeButton("Cancel", 
                    new DialogInterface.OnClickListener() { 
                        public void onClick(DialogInterface dialog, 
                                int whichButton) { 
                            Toast.makeText(getBaseContext(), "Cancel clicked!", 
                                    Toast.LENGTH_SHORT).show(); 
                        } 
                    }); 
 
            builder.setMultiChoiceItems(items, itemsChecked, 
                    new DialogInterface.OnMultiChoiceClickListener() { 
                        public void onClick(DialogInterface dialog, int which, 
                                boolean isChecked) { 
                            Toast.makeText( 
                                    getBaseContext(), 
                                    items[which] 
                                            + (isChecked ? " checked!" 
                                                    : " unchecked!"), 
                                    Toast.LENGTH_SHORT).show(); 
                        } 
                    }); 
            return builder.create(); 
        } 
        return null; 
    } 
 
 
 

摘自 manoel的專欄