android dialog 学习

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如果你希望自定义你的对话框, 可以扩展Dialog类.

　　Showing a Dialog 显示对话框

　　一个对话框总是被创建和显示为一个Activity的一部分. 你应该在Activity的onCreateDialog(int)中创建对话框. 当你使用这个回调函数时,Android系统自动管理每个对话框的状态并将它们和Activity连接, 将Activity变为对话框的"所有者". 这样,每个对话框从Activity继承一些属性. 例如,当一个对话框打开时, MENU键会显示Activity的菜单, 音量键会调整Activity当前使用的音频流的音量.

* 动态改变对话框值
* 关键点：onPrepareDialog方法里面调用 removeDialog(id);
* 对话框调用执行顺序 showDialog() -> onCreateDialog() -> onPrepareDialog() -> removeDialog()
* public final boolean showDialog(int id, Bundle args) {
        if (mManagedDialogs == null) {
            mManagedDialogs = new SparseArray<ManagedDialog>();
        }
        ManagedDialog md = mManagedDialogs.get(id);
        if (md == null) {
            md = new ManagedDialog();
            md.mDialog = createDialog(id, null, args);
            if (md.mDialog == null) {
                return false;
            }
            mManagedDialogs.put(id, md);
        }

        md.mArgs = args;
        onPrepareDialog(id, md.mDialog, args);
        md.mDialog.show();
        return true;
   }
分析showDialog方法可知
android 创建的Dialog对象统一由ManagedDialogs进行管理,如果想重新执行createDialog()方法，需先将Dialog,移出ManagedDialogs;

public class DialogActivity extends Activity implements OnClickListener {
    private static final int DIALOG_SORT_MAILS = 0x1;
    public Button mButton;
    public boolean flag;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.dialog_demo);

        LinearLayout layout = (LinearLayout) findViewById(R.id.nextMail);
        mButton = new Button(this);
        mButton.setText("对话框1");
        layout.addView(mButton);
        mButton.setOnClickListener(this);
        setTitle("动态改变对话框值");
    }

    @Override
    public void onClick(View v) {
        showDialog(DIALOG_SORT_MAILS);
    }

    @Override
    public void onPrepareDialog(int id, Dialog dialog) {
        Log.d("tag", "onPrepareDialog ");
        switch (id) {
        case (DIALOG_SORT_MAILS):
            Log.d("tag", "removeDialog ");
            removeDialog(id);
            break;
        }
    }

    @Override
    protected Dialog onCreateDialog(int id) {
        Log.d("tag", "onCreateDialog ");
        AlertDialog.Builder builder = new AlertDialog.Builder(
                DialogActivity.this);
        switch (id) {

        case DIALOG_SORT_MAILS:
            builder.setTitle("title");
            if (flag) {
                flag = false;
                mButton.setText("对话框1");
                builder.setSingleChoiceItems(R.array.dialog_demo1_entries, 0,
                        new DialogInterface.OnClickListener() {
                            public void onClick(DialogInterface dialog, int item) {

                                dialog.cancel();
                            }
                        });
            } else {
                flag = true;
                mButton.setText("对话框2");
                builder.setSingleChoiceItems(
                        R.array.dialog_demo2_entries, 0,
                        new DialogInterface.OnClickListener() {
                            public void onClick(DialogInterface dialog, int item) {

                                dialog.cancel();
                            }
                        });
            }
            builder.setNegativeButton("cancel",
                    new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog,
                                int whichButton) {
                            dialog.cancel();
                        }
                    });
            break;
        }
        AlertDialog alert = builder.create();
        return alert;

}

      WindowManager wm = getWindowManager();
        Display display = wm.getDefaultDisplay();
        LayoutParams lp = dialog.getWindow().getAttributes();