乐学成语(成语分类列表显示)

   这次完成的是乐学成语中成语分类列表的显示，也就是对ListView控件的应用，对ListView的界面进行编辑制定，效果如图所示，这里也应用到了打招呼案例中的点击产生响应的操作，既当点击某一类别时，弹出此类别名称

              

1.首先需要准备好图片资源、文字资源，将图片资源导入到drawable中，文字资源写入values中的strings.xml中，如下所示：

<span style="font-size:14px;"><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></span>

2.定义一个实体类，作为ListView适配器的适配类型，建类Category，代码如下：

package cn.edu.bztc.happyldiom.entity;public class Category {private String name;//类别名称private int imageId;//类别对应的图片public Category(String name, int imageId) {super();this.name = name;this.imageId = imageId;}public String getName() {return name;}public void setName(String name) {this.name = name;}public int getImageId() {return imageId;}public void setImaged(int imageId) {this.imageId = imageId;}}

3.layout下新建activity_study.xml，构建一个轮廓ListView控件，代码如

<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:listSelector="#00000000"        android:layout_alignParentTop="true"        android:layout_centerHorizontal="true"        android:layoutAnimation="@anim/anim_layout_listview"        >    </ListView>    </RelativeLayout>

4.然后为ListView的子项指定一个自定义布局，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="match_parent"        android:layout_height="wrap_content"        android:text="animal"         android:gravity="center"        android:textAppearance="?android:attr/textAppearanceLarge"/></LinearLayout>

5.在应用的包下创建自定义的适配器CategoryAdapter,适配器继承自ArrayAdapter,并将泛型指定为Category类，代码如下：

package cn.edu.bztc.happyldiom.adapter;import java.util.List;import cn.edu.bztc.happyldiom.R;import cn.edu.bztc.happyldiom.entity.Category;import android.content.Context;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.ArrayAdapter;import android.widget.ImageView;import android.widget.TextView;public class CategoryAdapter extends ArrayAdapter<Category>{private int resourceId;public CategoryAdapter(Context context, int resource,List<Category> objects) {             //写了父类的构造方法，用于将上下文、listview子项布局的ID和数据dou传递进来super(context, resource, objects);resourceId=resource;}@Overridepublic View getView(int position,View convertView,ViewGroup parent){//重写了getView()方法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(resourceId, null);//LayoutInflater</span><span style="font-size:14px;">为子项加载我们传入的布局viewHolder=new ViewHolder();viewHolder.categoryImage=(ImageView) view.findViewById(R.id.category_image);//获取ImageView实例viewHolder.categoryName=(TextView) view.findViewById(R.id.category_name);//获取TextView实例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.getImageId());//设置显示的图片viewHolder.categoryName.setText(category.getName());//设置显示的文字return view;//最后将布局返回}class ViewHolder{ImageView categoryImage;TextView categoryName;}}

6.新建StudyActivity继承自Activity,代码如下：

<span style="font-size:14px;">package cn.edu.bztc.happyldiom.activity;import java.util.ArrayList;import java.util.List;import cn.edu.bztc.happyldiom.R;import cn.edu.bztc.happyldiom.adapter.CategoryAdapter;import cn.edu.bztc.happyldiom.entity.Category;import android.os.Bundle;import android.app.Activity;import android.content.Intent;import android.content.res.Resources;import android.view.Menu;import android.view.View;import android.widget.AdapterView;import android.widget.AdapterView.OnItemClickListener;import android.widget.ListView;import android.widget.Toast;public class StudyActivity extends Activity {private List<Category> categoryList;private String[] category_names;private int[] category_images;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_study);intiCategories();  // 初始化类别CategoryAdapter adapter = new CategoryAdapter(this, //创建了CategoryAdapter对象R.layout.category_item, categoryList);ListView listView = (ListView) findViewById(R.id.lvCategories);listView.setAdapter(adapter);  //将CategoryAdapter作为适配器传递给ListViewlistView.setOnItemClickListener(new OnItemClickListener() {@Overridepublic void onItemClick(AdapterView<?> parent, View view,int position, long id) {switch (position) {case 0:Intent intent = new Intent(StudyActivity.this,StudyAnimalActivity.class);startActivity(intent);break;default:break;}Category category = categoryList.get(position);Toast.makeText(StudyActivity.this, category.getName(),Toast.LENGTH_LONG).show();//用于做出响应，弹出相应的名称}});}private void intiCategories() {categoryList = new ArrayList<Category>();Resources resources = getResources();category_names = resources.getStringArray(R.array.category);//将所有的目录名称导入category_images = new int[] { R.drawable.category_animal,   //将所有对应的图片导入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_images[i]));//全部添加到目录列表中}}@Overridepublic boolean onCreateOptionsMenu(Menu menu) {// Inflate the menu; this adds items to the action bar if it is present.getMenuInflater().inflate(R.menu.study, menu);return true;}}</span><span style="font-size: 18px;"></span>

7.这样完成了listview界面的制定，在运行程序之前记得修改AndroidManifest.xml文件将StudyActivity变为入口类，运行一下程序。