listview 中的不同 item 实现

原文 链接 http://android.leocardz.com/multiple-layout-listview/

Basically, you have to follow these steps:

• Create the custom layous;
• Create a custom adapter;
• Override getViewTypeCount() method in your custom adapter with the amount of layouts you're gonna use in your listview;
• Override getItemViewType(int position) method also in your custom adapter to return the current item's view type;
• Additionally, it's essential to use a view holder to avoid memory leaks.

Take a look in the code below.

First, we create custom layouts. In this case, four types.

首先,要按照下面的步骤:

1,创建自定义布局

2,新建自定义adpter

3,override getViewTypeCount()方法,返回值就是item的种类数

4,override getItemViewType(int position) 方法,返回当前position item类型

5,使用view holder避免内存泄露

首先创建自定义布局

// even  <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:background="#ff500000"    android:layout_height="match_parent">     <TextView        android:id="@+id/text"        android:textColor="@android:color/white"        android:layout_width="match_parent"        android:layout_gravity="center"        android:textSize="24sp"        android:layout_height="wrap_content" />  </LinearLayout>

// odd  <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:background="#ff001f50"    android:gravity="right"    android:layout_height="match_parent">     <TextView        android:id="@+id/text"        android:textColor="@android:color/white"        android:layout_width="wrap_content"        android:layout_gravity="center"        android:textSize="28sp"        android:layout_height="wrap_content"  />  </LinearLayout>

// white  <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:background="#ffffffff"    android:gravity="right"    android:layout_height="match_parent">     <TextView        android:id="@+id/text"        android:textColor="@android:color/black"        android:layout_width="wrap_content"        android:layout_gravity="center"        android:textSize="28sp"        android:layout_height="wrap_content"   />  </LinearLayout>

// black  <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:background="#ff000000"    android:layout_height="match_parent">     <TextView        android:id="@+id/text"        android:textColor="@android:color/white"        android:layout_width="wrap_content"        android:layout_gravity="center"        android:textSize="33sp"        android:layout_height="wrap_content"   />  </LinearLayout>

然后新建一个listviewitem.class存放item数据

public class ListViewItem {        private String text;        private int type;         public ListViewItem(String text, int type) {            this.text = text;            this.type = type;        }         public String getText() {            return text;        }         public void setText(String text) {            this.text = text;        }         public int getType() {            return type;        }         public void setType(int type) {            this.type = type;        }     }

在然后,新建一个viewholer .强烈推荐.因为可以让系统保持item layout重用参考当item消失和显示时.如果不使用,每一次显示item的时候,系统都回去新建一个item 参考,导致app内存泄露

After that, we create a view holder. It's strongly recommended because Android OS keeps the layout reference to reuse your item when it disappears and appears back on the screen. If you don't use this approach, every single time that your item appears on the screen Android OS will create a new one and causing your app to leak memory.

public class ViewHolder {        TextView text;         public ViewHolder(TextView text) {            this.text = text;        }         public TextView getText() {            return text;        }         public void setText(TextView text) {            this.text = text;        }     }

Finally, we create our custom adapter overriding getViewTypeCount() and getItemViewType(int position).

最后,overriding getViewTypeCount() 和 getItemViewType(int position)方法

public class CustomAdapter extends ArrayAdapter {        public static final int TYPE_ODD = 0;        public static final int TYPE_EVEN = 1;        public static final int TYPE_WHITE = 2;        public static final int TYPE_BLACK = 3;        private ListViewItem[] objects;        @Override        public int getViewTypeCount() {            return 4;        }        @Override        public int getItemViewType(int position) {            return objects[position].getType();        }        public CustomAdapter(Context context, int resource, ListViewItem[] objects) {            super(context, resource, objects);            this.objects = objects;        }        @Override        public View getView(int position, View convertView, ViewGroup parent) {            ViewHolder viewHolder = null;            ListViewItem listViewItem = objects[position];            int listViewItemType = getItemViewType(position);            if (convertView == null) {                if (listViewItemType == TYPE_EVEN) {                    convertView = LayoutInflater.from(getContext()).inflate(R.layout.type_even, null);                } else if (listViewItemType == TYPE_ODD) {                    convertView = LayoutInflater.from(getContext()).inflate(R.layout.type_odd, null);                } else if (listViewItemType == TYPE_WHITE) {                    convertView = LayoutInflater.from(getContext()).inflate(R.layout.type_white, null);                } else {                    convertView = LayoutInflater.from(getContext()).inflate(R.layout.type_black, null);                }                TextView textView = (TextView) convertView.findViewById(R.id.text);                viewHolder = new ViewHolder(textView);                convertView.setTag(viewHolder);            } else {                viewHolder = (ViewHolder) convertView.getTag();            }            viewHolder.getText().setText(listViewItem.getText());            return convertView;        }    }

activity 文件

public class MainActivity extends ActionBarActivity {     private ListView listView;     @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);         setContentView(R.layout.activity_main); // here, you can create a single layout with a listview         listView = (ListView) findViewById(R.id.listview);         final ListViewItem[] items = new ListViewItem[40];         for (int i = 0; i < items.length; i++) {            if (i == 4) {                items[i] = new ListViewItem("White " + i, CustomAdapter.TYPE_WHITE);            } else if (i == 9) {                items[i] = new ListViewItem("Black " + i, CustomAdapter.TYPE_BLACK);            } else if (i % 2 == 0) {                items[i] = new ListViewItem("EVEN " + i, CustomAdapter.TYPE_EVEN);            } else {                items[i] = new ListViewItem("ODD " + i, CustomAdapter.TYPE_ODD);            }        }         CustomAdapter customAdapter = new CustomAdapter(this, R.id.text, items);        listView.setAdapter(customAdapter);        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {            @Override            public void onItemClick(AdapterView adapterView, View view, int i, long l) {                Toast.makeText(getBaseContext(), items[i].getText(), Toast.LENGTH_SHORT).show();            }        });     }}

效果图

代码地址 github