Android 学习笔记（9）—— ListView

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <ListView
        android:id="@+id/list_item"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
    ></ListView>
</LinearLayout>

public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    //要显示的数据
    String[] strs = {"基神","B神","翔神","曹神","J神"};
    //创建ArrayAdapter
    ArrayAdapter<String> adapter = new ArrayAdapter<String>
                (this,android.R.layout.simple_expandable_list_item_1,strs);
    //获取ListView对象，通过调用setAdapter方法为ListView设置Adapter设置适配器
    ListView list_test = (ListView) findViewById(R.id.list_test);
    list_test.setAdapter(adapter);
    }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="horizontal"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">
    <ImageView
        android:id="@+id/content_image"
        android:layout_width="64dp"
        android:layout_height="64dp"
        android:scaleType="fitCenter"
        android:baselineAlignBottom="true"
        android:paddingLeft="8dp"
    />
    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:paddingTop="5dp"
        android:orientation="vertical">
        <TextView
        android:id="@+id/text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textColor="#1D1D1C"
        android:gravity="center"
        android:paddingLeft="10dp"
        android:textSize="14sp"
    />
        <TextView
        android:id="@+id/text2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:textColor="#B4B4B9"
        android:paddingLeft="10dp"
        android:layout_marginLeft="10dp"
        android:layout_marginBottom="10dp"
        android:textSize="12sp"
    />
       </LinearLayout>
</LinearLayout>

public class Content {
private String name,say;
    private int imageId;
    public Content(String name, String say, int imageId) {
        this.name = name;
        this.imageId = imageId;
        this.say = say;
    }
    public String getName() {
        return name;
    }
    public int getImageId() {
        return imageId;
    }
    public String getSay() {
        return say;
    }
}

public class ContentAdapter extends ArrayAdapter<Content>{
private int resourceId;   
// context 表示我们要传入的内容，比如this 
// resource 表示我们要传进来刚刚新建的layout文件
// List<Content> object 要传入的数据
public ContentAdapter(Context context, int resource, List<Content> object) {
    super(context, resource, object);
    resourceId = resource;
}
@Override
//converView 以前的布局的缓存
// position 获取每一个Item的值，填充到制定的XML文件中
// parent 当前布局会被加载到父布局中
public View getView(int position, View convertView, ViewGroup parent) {
    View view;
    Content content = getItem(position);  //获取当前的Content实例
    // 优化，这样可以减少重复加载；layout 布局文件
    if(convertView == null) {  //如果刚开始创建
    // LayoutInflater .. 表示动态加载布局，第二个参数我们一般选null
    view = LayoutInflater.from(getContext()).inflate(resourceId, null); 
}
else {
            view = convertView;  //表示已经创建过了
}
    // 获取xml文件中的控件
    ImageView ContentImage = (ImageView) view.findViewById(R.id.content_image);
    TextView ContentName = (TextView)view.findViewById(R.id.text);
    TextView ContentSay = (TextView)view.findViewById(R.id.text2);
    // 重写方法，让图片和文字显示出来
    ContentImage.setImageResource(content.getImageId());
    ContentName.setText(content.getName());
    ContentSay.setText(content.getSay());
    return view;  //返回我们重新定制的布局
}
}

public class MainActivity extends AppCompatActivity {
private String[] name = {"自古屌丝多薄命","无形被黑 最为致命","我赵日天第一个不服","无敌锐神"};
    private String[] say  = {"要脸你就输了","你的贱就是我的贱","我将带头日狗","断剑重铸之日 骑士归来之时"};
    
    private List<Content> contentList = new ArrayList<Content>();
    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.linearlayout);
    initContens();  //初始化
    ContentAdapter adapter = new ContentAdapter(MainActivity.this,
    R.layout.content,contentList);  // 传入参数，我们自定义的适配器
    ListView listView = (ListView)findViewById(R.id.list_item);
    listView.setAdapter(adapter);  //显示出来
// listView.setOnItemClickListener(new ArrayAdapterClick(this,contentList));
}
public void initContens(){
contentList.add(new Content(name[0],say[0],R.drawable.image3));
contentList.add(new Content(name[1],say[1],R.drawable.image4));
contentList.add(new Content(name[2],say[2],R.drawable.image5));
contentList.add(new Content(name[3],say[3],R.drawable.image6));
}

public class ArrayAdapterClick implements AdapterView.OnItemClickListener{
    private Context context;
    private List<Content> contentList;
    public ArrayAdapterClick(Context context,List<Content> contentList){
        this.context = context;
        this.contentList = contentList;
}
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
        Content content = contentList.get(position);  //获取指定位置的数据
        Toast.makeText(context,content.getName()+"\n"+content.getSay(),Toast.LENGTH_SHORT).show();
    }
}

public class BaseAdapterDataClick implements AdapterView.OnItemClickListener{
private BaseAdaperData object;
    private Context context;
    public BaseAdapterDataClick(Context context,BaseAdaperData object){
        this.context = context;
        this.object = object;
}
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
    Content content = object.getItem(position);
    Toast.makeText(context,content.getName()+"\n"+"  "+content.getSay(),Toast.LENGTH_SHORT).show();
    }
}

public class BaseAdaperData extends BaseAdapter{
     private String[] name = {"自古屌丝多薄命","无形被黑 最为致命","我赵日天第一个不服","我良辰最喜欢对有能力的人出手","无敌锐神"};
     private String[] say  = {"要脸你就输了","你的贱就是我的贱","我将带头日狗","我有一百种方法让你混不下去","断剑重铸之日 骑士归来之时"};
     //private String[] picture = {"R.drawable.image4","R.drawable.image5","R.drawable.image6","R.drawable.image7"};
    //  这里初始化，我们在里面，用数组的方式
     private Content[] data= new Content[]{
             new Content(name[0],say[0],R.drawable.image3),
             new Content(name[1],say[1],R.drawable.image4),
             new Content(name[2],say[2],R.drawable.image5),
             new Content(name[3],say[3],R.drawable.image6),
             new Content(name[4],say[4],R.drawable.image7),
     };
    private Context context;  // 因为初始化什么的都在里面了，所以我们就只要传入context就行了
    public BaseAdaperData(Context context){
        this.context = context;
    }
    // 不要也行，直接传context，只是用getContext()这样标准一点
     public Context getContext() {
         return context;
     }
     @Override
    public int getCount() {
        return data.length;  //返回list所包裹的大小
    }
    @Override
    public Content getItem(int position) {
        return data[position];  //返回指定位置的内容
    }
    @Override
    public long getItemId(int position) {
        return 0;
    }
    class ViewHolder{
        ImageView contentImage;
        TextView  contentName;
        TextView  contentSay;
    }
    public View getView(int position, View convertView, ViewGroup parent) {
        View view;
        //  优化
        ViewHolder viewHolder;  // 对控件进行优化
        if(convertView == null){
            // getContext() 用context替代也行
            view = LayoutInflater.from(getContext()).inflate(R.layout.baseapaper,null);
            viewHolder = new ViewHolder();  //初始化
            viewHolder.contentImage = (ImageView) view.findViewById(R.id.imageview);
            viewHolder.contentName = (TextView) view.findViewById(R.id.text);
            viewHolder.contentSay = (TextView) view.findViewById(R.id.text2);
            view.setTag(viewHolder);  //  将ViewHolder 储存在View中
        }else{
            view = convertView;
            viewHolder = (ViewHolder)view.getTag();  // 重新获得ViewHolder
        }
        Content content = getItem(position); //获取实例
        viewHolder.contentImage.setImageResource(content.getImageId());
        viewHolder.contentName.setText(content.getName());
        viewHolder.contentSay.setText(content.getSay());
        return view;
    }
}