Android example source code file (ViewSwitcher.java)

This example Android source code file (ViewSwitcher.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" ^TM.

Java - Android tags/keywords

android, attributeset, can't, content, illegalstateexception, layoutparams, override, ui, util, utilities, utils, view, viewanimator, viewfactory, viewswitcher

The ViewSwitcher.java Android example source code

/*
 * Copyright (C) 2006 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.widget;

import android.content.Context;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;

/**
 * {@link ViewAnimator} that switches between two views, and has a factory
 * from which these views are created.  You can either use the factory to
 * create the views, or add them yourself.  A ViewSwitcher can only have two
 * child views, of which only one is shown at a time.
 */
public class ViewSwitcher extends ViewAnimator {
    /**
     * The factory used to create the two children.
     */
    ViewFactory mFactory;

    /**
     * Creates a new empty ViewSwitcher.
     *
     * @param context the application's environment
     */
    public ViewSwitcher(Context context) {
        super(context);
    }

    /**
     * Creates a new empty ViewSwitcher for the given context and with the
     * specified set attributes.
     *
     * @param context the application environment
     * @param attrs a collection of attributes
     */
    public ViewSwitcher(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    /**
     * {@inheritDoc}
     *
     * @throws IllegalStateException if this switcher already contains two children
     */
    @Override
    public void addView(View child, int index, ViewGroup.LayoutParams params) {
        if (getChildCount() >= 2) {
            throw new IllegalStateException("Can't add more than 2 views to a ViewSwitcher");
        }
        super.addView(child, index, params);
    }

    /**
     * Returns the next view to be displayed.
     *
     * @return the view that will be displayed after the next views flip.
     */
    public View getNextView() {
        int which = mWhichChild == 0 ? 1 : 0;
        return getChildAt(which);
    }

    private View obtainView() {
        View child = mFactory.makeView();
        LayoutParams lp = (LayoutParams) child.getLayoutParams();
        if (lp == null) {
            lp = new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
        }
        addView(child, lp);
        return child;
    }

    /**
     * Sets the factory used to create the two views between which the
     * ViewSwitcher will flip. Instead of using a factory, you can call
     * {@link #addView(android.view.View, int, android.view.ViewGroup.LayoutParams)}
     * twice.
     *
     * @param factory the view factory used to generate the switcher's content
     */
    public void setFactory(ViewFactory factory) {
        mFactory = factory;
        obtainView();
        obtainView();
    }

    /**
     * Reset the ViewSwitcher to hide all of the existing views and to make it
     * think that the first time animation has not yet played.
     */
    public void reset() {
        mFirstTime = true;
        View v;
        v = getChildAt(0);
        if (v != null) {
            v.setVisibility(View.GONE);
        }
        v = getChildAt(1);
        if (v != null) {
            v.setVisibility(View.GONE);
        }
    }

    /**
     * Creates views in a ViewSwitcher.
     */
    public interface ViewFactory {
        /**
         * Creates a new {@link android.view.View} to be added in a
         * {@link android.widget.ViewSwitcher}.
         *
         * @return a {@link android.view.View}
         */
        View makeView();
    }
}