activity變身為dialog可以實現多功能的dialog，閒話少說直接上程式碼！

MainActivity.class

/**
 * Activity偽裝成的Dialog需要繼承Activity
 * 彈窗Activity需要新增主題Theme
 */
public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    public
 
 void start(View view) {
        startActivity(new Intent(MainActivity.this, DialogActivity.class));
    }
}

activity_mian.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height
 
="match_parent"
    tools:context="jpceshi.jiaxiao.com.dialogactivity.MainActivity">

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:onClick="start"
        android:text="跳轉" />
</LinearLayout>

跳轉後出現的dialog樣式

DialogActivity .class

/**
在edittext中輸入內容後點擊button會將內容直接顯示到textView中。
*/
public class DialogActivity extends Activity {
    private EditText mEditText;
    private Button mButton;
    private TextView mTextView;
    private String str;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_dialog);
        initView();
    }

    private void initView() {
        mEditText = (EditText) findViewById(R.id.edtext);
        mTextView = (TextView) findViewById(R.id.tvshow);
        mEditText.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {

            }

            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {

            }

            @Override
            public void afterTextChanged(Editable s) {
                str = s.toString();
            }
        });
    }

    public void addText(View view) {
        if (str != null) {
            mTextView.setText(str);
        } else {
            mTextView.setText("null");
        }
    }
}

activity_dialog.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="200dp"
    android:layout_height="200dp"
    android:orientation="vertical"
    tools:context="jpceshi.jiaxiao.com.dialogactivity.activity.DialogActivity">

    <EditText
        android:id="@+id/edtext"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@android:drawable/editbox_background"
        android:gravity="center"
        android:hint="請輸入"
        android:textColor="@android:color/black"
        android:textColorHint="@android:color/holo_blue_light" />

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@android:drawable/button_onoff_indicator_on"
        android:onClick="addText"
        android:text="新增" />

    <TextView
        android:id="@+id/tvshow"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:textColor="@android:color/black" />
</LinearLayout>

注：
最重要的一步是：在AndroidManifest.xml檔案中給需要顯示成dialog樣式的
Activity新增 android:theme=”@android:style/Theme.Dialog”（系統自帶 的樣式，也可以自定義樣式）