ListView是開發中最常用的控件了，但是總是會寫重復的代碼，浪費時間又沒有意義。
最近參考一些資料，發現一個萬能ListView適配器，代碼量少，節省時間，總結一下分享給大家。
首先有一個自定義的Adapter繼承於BaseAdapter，下面是自定義的Adapter，精華在getView()方法中
package com.example.mylistview.util; import java.util.List; import android.content.Context; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.BaseAdapter; public abstract class CommonAdapter<T> extends BaseAdapter { /** * 上下文 */
private Context mContext; /** * 實體類集合 */
private List<T> mDatas; private LayoutInflater mInflater; /** * 控件id */
private int mlayoutId; public CommonAdapter(Context context, List<T> datas, int layoutId) { this.mContext = context; this.mDatas = datas; this.mlayoutId = layoutId; mInflater = LayoutInflater.from(context); } @Override public int getCount() { // TODO Auto-generated method stub
return mDatas.size(); } @Override public T getItem(int arg0) { // TODO Auto-generated method stub
return mDatas.get(arg0); } @Override public long getItemId(int arg0) { // TODO Auto-generated method stub
return arg0; } @Override public View getView(int arg0, View arg1, ViewGroup arg2) { // TODO Auto-generated method stub
ViewHolder holder = ViewHolder.get(mContext, arg1, arg2, mlayoutId, arg0); convert(holder, getItem(arg0)); return holder.getConvertView(); } public abstract void convert(ViewHolder holder, T t); }
以上的抽象方法convert(ViewHolder holder, T t)；就相當於以前通用代碼中的
viewHolder.mTextView = (TextView) convertView .findViewById(R.id.id_tv_title);
viewHolder.mTextView.setText(Bean.getName());
找到控件的id再去設施setText等重復的代碼方法中的參數ViewHolder holder, T t holder就相當於以前通用代碼中的viewHolder，t就相當於一個自己定義的實體類Bean。
以上代碼中getView()方法中有一個ViewHolder是需要自己聲明的，以下是代碼以及詳細注釋：
package com.example.mylistview.util; import android.content.Context; import android.graphics.Bitmap; import android.renderscript.Type; import android.util.SparseArray; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.ImageView; import android.widget.TextView; public class ViewHolder { /** * SparseArray類存放View集合 */
private SparseArray<View> mViews; /** * */
private int mPosition; /** * 布局文件 */
private View mConvertView; public View getConvertView() { return mConvertView; } public ViewHolder(Context context, ViewGroup parent, int layoutId, int position) { this.mViews = new SparseArray<View>(); this.mPosition = position; this.mConvertView = LayoutInflater.from(context).inflate(layoutId, parent, false); this.mConvertView.setTag(this); } /** * 拿到一個ViewHolder對象 * @param context * @param convertView * @param parent * @param layoutId * @param position * @return
*/
public static ViewHolder get(Context context, View convertView, ViewGroup parent, int layoutId, int position) { if (null == convertView) { return new ViewHolder(context, parent, layoutId, position); } else { ViewHolder holder = (ViewHolder) convertView.getTag(); holder.mPosition = position; return holder; } } /** * 通過控件的id獲取對應的控件，如果沒有則加入views * @param viewId * @return
*/
public <T extends View> T getView(int viewId) { View view = mViews.get(viewId); if (null == view) { view = mConvertView.findViewById(viewId); mViews.put(viewId, view); } return (T) view; } /** * 為TextView設置字符串 * @param viewId * @param text * @return
*/
public ViewHolder setText(int viewId, String text) { TextView tv = getView(viewId); tv.setText(text); return this; } /** * 為ImageView設置圖片 * * @param viewId * @param drawableId * @return
*/
public ViewHolder setImageResource(int viewId, int drawableId) { ImageView view = getView(viewId); view.setImageResource(drawableId); return this; } public int getPosition() { return mPosition; } }
再寫一個Adapter繼承於萬能適配器CommonAdapter，還是要寫一個自己的Adapter,因為一個項目可能會有多個ListView，但是每個的item元素，布局都會有所不同的，這個淚用來區分不同的ListView與自己所對應的item.這個代碼量較少完全可以寫成內部類在Activity.java中.
package com.example.mylistview.adapter; import java.util.List; import android.content.Context; import android.view.View; import android.view.View.OnClickListener; import android.widget.CheckBox; import com.example.mylistview.R; import com.example.mylistview.domain.Bean; import com.example.mylistview.util.CommonAdapter; import com.example.mylistview.util.ViewHolder; public class MyAdapter extends CommonAdapter<Bean> { public MyAdapter(Context context, List<Bean> datas, int layoutId) { super(context, datas, layoutId); // TODO Auto-generated constructor stub
} @Override public void convert(ViewHolder holder, final Bean bean) { // TODO Auto-generated method stub
holder.setText(R.id.tv_title, bean.getTitle()) .setText(R.id.tv_desc, bean.getDesc()) .setText(R.id.tv_time, bean.getTime()) .setText(R.id.tv_phone, bean.getPhone()); /** * 防止CheckBox混亂 */
final CheckBox cBox = (CheckBox)(holder.getView(R.id.cb)); if (cBox != null) { cBox.setChecked(bean.isChecked()); cBox.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { bean.setChecked(cBox.isChecked()); } }); } } }
優化之后用適配器的時候就簡單多了下面是實體類,item和MainActivity.java中的代碼：
實體類：
package com.example.mylistview.domain; public class Bean { private String title; private String desc; private String time; private String phone; private boolean isChecked; public boolean isChecked() { return isChecked; } public void setChecked(boolean isChecked) { this.isChecked = isChecked; } /** * @param title * @param desc * @param time * @param phone */
public Bean(String title, String desc, String time, String phone) { this.title = title; this.desc = desc; this.time = time; this.phone = phone; } public String getTitle() { return title; } public void setTitle(String title) { this.title = title; } public String getDesc() { return desc; } public void setDesc(String desc) { this.desc = desc; } public String getTime() { return time; } public void setTime(String time) { this.time = time; } public String getPhone() { return phone; } public void setPhone(String phone) { this.phone = phone; } }
MainActivity.java：
重點代碼：
參數有上下文，集合，和自己對應的item就可以了
adapter = new MyAdapter(this, mDatas, R.layout.item);
package com.example.mylistview.ui; import java.util.ArrayList; import java.util.List; import android.app.Activity; import android.content.Intent; import android.os.Bundle; import android.view.View; import android.widget.AdapterView; import android.widget.AdapterView.OnItemClickListener; import android.widget.ListView; import com.example.mylistview.R; import com.example.mylistview.adapter.MyAdapter; import com.example.mylistview.domain.Bean; public class MainActivity extends Activity { private ListView listView; private List<Bean> mDatas; /** * 適配器 */
private MyAdapter adapter; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); initView(); initData(); listener(); } private void listener() { // TODO Auto-generated method stub
listView.setOnItemClickListener(new OnItemClickListener() { @Override public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) { // TODO Auto-generated method stub
startActivity(new Intent(MainActivity.this, SecondActivity.class)); } }); } private void initData() { // TODO Auto-generated method stub
mDatas = new ArrayList<Bean>(); Bean bean = new Bean("Android新技能 Get", "Android-打造萬能的ListView和GridView適配器", "2015-08-05", "10086"); mDatas.add(bean); bean = new Bean("撿到權志龍一個", "在星巴克撿到權志龍一個", "2015-08-06", "10086"); mDatas.add(bean); bean = new Bean("GetTOP一個", "在韓國首爾撿到TOP一個", "2015-08-07", "10086"); mDatas.add(bean); adapter = new MyAdapter(this, mDatas, R.layout.item); listView.setAdapter(adapter); } private void initView() { // TODO Auto-generated method stub
listView = (ListView) findViewById(R.id.listView); } }
item布局：
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="10dp" >
<CheckBox
android:focusable="false"
android:id="@+id/cb"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_centerInParent="true" />
<TextView
android:id="@+id/tv_title"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="10dp"
android:singleLine="true"
android:text="Android新技能 Get" />
<TextView
android:id="@+id/tv_desc"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@id/tv_title"
android:layout_marginTop="10dp"
android:layout_toLeftOf="@id/cb"
android:maxLines="2"
android:text="Android-打造萬能的ListView和GridView適配器"
android:textColor="#898989" />
<TextView
android:id="@+id/tv_time"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/tv_desc"
android:layout_marginTop="10dp"
android:text="2015-08-05"
android:textColor="#898989"
android:textSize="12sp" />
<TextView
android:id="@+id/tv_phone"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_below="@id/tv_desc"
android:layout_marginTop="10dp"
android:background="#20793D"
android:maxLines="1"
android:text="10086"
android:padding="4dp"
android:textColor="#FFF" />
</RelativeLayout>
效果圖：
用這個去適配另一個不同的布局：
新布局的Adapter一樣繼承自己的萬能adapter:CommonAdapter
package com.example.mylistview.adapter; import java.util.List; import java.util.Map; import android.content.Context; import com.example.mylistview.R; import com.example.mylistview.util.CommonAdapter; import com.example.mylistview.util.ViewHolder; public class SecondAdapter extends CommonAdapter<Map<String, String>> { public SecondAdapter(Context context, List<Map<String, String>> datas, int layoutId) { super(context, datas, layoutId); // TODO Auto-generated constructor stub
} @Override public void convert(ViewHolder holder, Map<String, String> t) { // TODO Auto-generated method stub
holder.setText(R.id.tv_item2values, t.get("values")); } }
Activity.java代碼：
package com.example.mylistview.ui; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import android.app.Activity; import android.os.Bundle; import android.widget.ListView; import com.example.mylistview.R; import com.example.mylistview.adapter.MyAdapter; import com.example.mylistview.adapter.SecondAdapter; public class SecondActivity extends Activity { private ListView listView_second; private SecondAdapter secondAdapter; private List<Map<String, String>> lists = new ArrayList<Map<String, String>>(); @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_second); initView(); initData(); } private void initData() { // TODO Auto-generated method stub
for (int i = 0; i < 4; i++) { Map map = new HashMap<String, String>(); map.put("values", "條目" + i); lists.add(map); } secondAdapter = new SecondAdapter(this, lists, R.layout.item2); listView_second.setAdapter(secondAdapter); } private void initView() { // TODO Auto-generated method stub
listView_second = (ListView) findViewById(R.id.listView_second); } }
item：
<?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:orientation="horizontal" >
<TextView
android:id="@+id/tv_item2values"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:text="ffffff"
android:layout_margin="16dp"
android:gravity="center" />
</LinearLayout>
效果圖：
備忘，希望能給大家帶來幫助。