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      1 /*
      2  * Copyright (C) 2006 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package android.widget;
     18 
     19 
     20 import android.content.Context;
     21 import android.util.AttributeSet;
     22 import android.view.View;
     23 import android.view.ViewGroup;
     24 
     25 /**
     26  * Specialized {@link android.widget.ViewSwitcher} that contains
     27  * only children of type {@link android.widget.TextView}.
     28  *
     29  * A TextSwitcher is useful to animate a label on screen. Whenever
     30  * {@link #setText(CharSequence)} is called, TextSwitcher animates the current text
     31  * out and animates the new text in.
     32  */
     33 public class TextSwitcher extends ViewSwitcher {
     34     /**
     35      * Creates a new empty TextSwitcher.
     36      *
     37      * @param context the application's environment
     38      */
     39     public TextSwitcher(Context context) {
     40         super(context);
     41     }
     42 
     43     /**
     44      * Creates a new empty TextSwitcher for the given context and with the
     45      * specified set attributes.
     46      *
     47      * @param context the application environment
     48      * @param attrs a collection of attributes
     49      */
     50     public TextSwitcher(Context context, AttributeSet attrs) {
     51         super(context, attrs);
     52     }
     53 
     54     /**
     55      * {@inheritDoc}
     56      *
     57      * @throws IllegalArgumentException if child is not an instance of
     58      *         {@link android.widget.TextView}
     59      */
     60     @Override
     61     public void addView(View child, int index, ViewGroup.LayoutParams params) {
     62         if (!(child instanceof TextView)) {
     63             throw new IllegalArgumentException(
     64                     "TextSwitcher children must be instances of TextView");
     65         }
     66 
     67         super.addView(child, index, params);
     68     }
     69 
     70     /**
     71      * Sets the text of the next view and switches to the next view. This can
     72      * be used to animate the old text out and animate the next text in.
     73      *
     74      * @param text the new text to display
     75      */
     76     public void setText(CharSequence text) {
     77         final TextView t = (TextView) getNextView();
     78         t.setText(text);
     79         showNext();
     80     }
     81 
     82     /**
     83      * Sets the text of the text view that is currently showing.  This does
     84      * not perform the animations.
     85      *
     86      * @param text the new text to display
     87      */
     88     public void setCurrentText(CharSequence text) {
     89         ((TextView)getCurrentView()).setText(text);
     90     }
     91 }
     92