乐学成语——显示学习列表

     1.使类别名称的旁边都有一个图样，修改values中的strings.xml文件如下：

<?xml version="1.0" encoding="utf-8"?><resources>    <string name="app_name">HappyIdiom</string>    <string name="action_settings">Settings</string>    <string name="hello_world">Hello world!</string>    <string name="animal">动物</string>    <string name="title_activity_main">MainActivity</string>    <string name="title_study">学习</string>    <string name="title_search">搜搜</string>    <string name="title_game">游戏</string>    <string name="title_save">收藏</string>    <string name="title_help">帮助</string>    <string-array name="category">        <item>动物类</item>        <item>自然类</item>        <item>人物类</item>        <item>季节类</item>        <item>数字类</item>        <item>寓言类</item>        <item>其他类</item>    </string-array></resources>

     2.定义一个实体类，做为ListView适配器的适配类型。在entity包下，新建类Category，代码如下：

package cn.edu.bztc.happyidiom.entity;public class Category {public String name;//类别名称private int imageld;//类别对应的图片public Category(String name,int imageld){super();this.name=name;this.imageld=imageld;}public String getName() {return name;}public int getImageld() {return imageld;}}

  name代表种类的名字。imageId表示类别对应图片的资源id。

     3.在layout下新建activity_study.xml文件，主要添加了一个ListView控件，代码如下：

<RelativeLayout 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"    android:background="@drawable/bg_ling"      tools:context=".StudyActivity" >    <ListView         android:id="@+id/lvCategories"        android:layout_width="match_parent"        android:layout_height="wrap_content"              android:layout_alignParentLeft="true"        android:layout_alignParentTop="true">     </ListView></RelativeLayout>

     4.为ListView的子项指定一个我们自定义的布局，在layout目录下新建category_item.xml，代码如下：

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:padding="10dp"    android:orientation="horizontal" >    <ImageView         android:id="@+id/category_image"        android:layout_width="wrap_content"        android:layout_height="wrap_content"           android:src="@drawable/category_animal"/>    <TextView         android:id="@+id/category_name"        android:layout_width="wrap_content"        android:text="@string/animal"        android:layout_height="wrap_content"        android:gravity="center"        android:textAppearance="?android:attr/textAppearanceLarge"/></LinearLayout>

  在这个布局中，我们定义了一个ImageView用于显示类别的图片，又定义了一个TextView用于显示类别的名称。

     4.在包adapter下新建一个自定义适配器CategoryAdapter，继承自ArryAdapter，并将泛型指定为Category类。代码如下：

public class CategoryAdapter extends ArrayAdapter<Category> {private int resourceld;public CategoryAdapter(Context context,int resource,List<Category> objects){super(context,resource,objects);resourceld=resource;}public View getView(int position,View convertView,ViewGroup parent){Category category=getItem(position);//获取当前项的Category实例View view;ViewHolder viewHolder;if(convertView==null){view=LayoutInflater.from(getContext()).inflate(resourceld, null);viewHolder=new ViewHolder();viewHolder.categoryImage=(ImageView)view.findViewById(R.id.category_image);viewHolder.categoryName=(TextView)view.findViewById(R.id.category_name);view.setTag(viewHolder);//将ViewHolder存储在View中}else {view=convertView;viewHolder=(ViewHolder)view.getTag();//重新获取ViewHolder}viewHolder.categoryImage.setImageResource(category.getImageld());viewHolder.categoryName.setText(category.getName());return view;}class ViewHolder{ImageView categoryImage;TextView categoryName;}}

     5.在activity包下新建StudyAcitvity类，继承自Activity，代码如下：

public class StudyActivity extends Activity {private List<Category>categoryList;private String[] category_names;private int[] category_image;protected void onCreate(Bundle savedInstanceState){super.onCreate(savedInstanceState);setContentView(R.layout.activity_study);initCategories();//初始化类别CategoryAdapter adapter=new CategoryAdapter(this, R.layout.category_item,categoryList);ListView listView=(ListView)findViewById(R.id.lvCategories);listView.setAdapter(adapter);listView.setOnItemClickListener(new OnItemClickListener(){public void onItemClick(AdapterView<?> adapterView,View view,int position,long id) {Category category=categoryList.get(position);Toast.makeText(StudyActivity.this, category.getName(),Toast.LENGTH_LONG).show();}}});}private void initCategories() {// TODO Auto-generated method stubcategoryList=new ArrayList<Category>();Resources resources=getResources();category_names=resources.getStringArray(R.array.category);category_image=new int[]{R.drawable.category_animal,R.drawable.category_nature,R.drawable.category_human,R.drawable.category_season,R.drawable.category_number,R.drawable.category_fable,R.drawable.category_other};for(int i=0;i<category_names.length;i++){categoryList.add(new Category(category_names[i], category_image[i]));}}public boolean onCreateOptionsMenu(Menu menu){ getMenuInflater().inflate(R.menu.study,menu); return true;}}

     6.修改AndroidManifest.xml文件，把StudyActivity变成入口类。运行程序并点击动物类，如图：

     7.下面我们为界面加入淡入淡出的动画效果，在res目录下新建anim目录，在下面创建anim_listview.xml文件，代码如下：

<?xml version="1.0" encoding="utf-8"?><alpha xmlns:android="http://schemas.android.com/apk/res/android"    android:duration="1000"     android:fromAlpha="0.0"    android:toAlpha="1.0">   </alpha>

  设置了一个Alpha动画，从无到有的过程。创建anim_layout_listview.xml文件，代码如下：

<?xml version="1.0" encoding="utf-8"?><layoutAnimation xmlns:android="http://schemas.android.com/apk/res/android"    android:animation="@anim/anim_listview"    android:animationOrder="random"    android:delay="0.2"></layoutAnimation>

    9. 修改activity_study.xml布局文件，代码如下：

<RelativeLayout 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"    android:background="@drawable/bg_ling"      tools:context=".StudyActivity" >    <ListView         android:id="@+id/lvCategories"        android:layout_width="match_parent"        android:layout_height="wrap_content"              android:layoutAnimation="@anim/anim_layout_listview"        android:layout_alignParentLeft="true"        android:layout_alignParentTop="true">     </ListView></RelativeLayout>

     8.将之前建立的主界面连起来。修改MainActivity，代码如下：

public class MainActivity extends TabActivity {private TabHost tabHost;protected void onCreate(Bundle savedInstanceState){super.onCreate(savedInstanceState);requestWindowFeature(Window.FEATURE_NO_TITLE);//取消标题栏setContentView(R.layout.activity_main);tabHost=getTabHost();addTab("study",R.string.title_study,R.drawable.study,StudyActivity.class);addTab("search",R.string.title_search,R.drawable.search,StudyActivity.class);addTab("game",R.string.title_game,R.drawable.game,StudyActivity.class);addTab("save",R.string.title_save,R.drawable.save,StudyActivity.class);addTab("help",R.string.title_help,R.drawable.help,StudyActivity.class);}private void addTab(String tag,int title_introduction,int title_icon,Class ActivityClass){tabHost.addTab(tabHost.newTabSpec(tag).setIndicator(getString(title_introduction), getResources().getDrawable(title_icon)).setContent(new Intent(this,ActivityClass)));}public boolean onCreateOptionsMenu(Menu menu){//inflate the menu;this adds items to the action bar if it is present.getMenuInflater().inflate(R.menu.main, menu);return true;}}

     10.通过Intent，将选项卡和对应的StudyActivity关联起来了。运行结果如图：