项目开发中经常需要去自定义适配器,若自定义适配器写得好整个界面就会非常的流畅,反之程序就歇菜了。下面先贴代码,再讲讲自定义适配器的过程中需要注意的细节。
首先是Activity的代码:
package com.example.textviewtest;import android.app.Activity;import android.content.Context;import android.os.Bundle;import android.widget.ListView;public class MainActivity extends Activity{ private static final String TAG = "MainActivity"; private String[] data = {"三星","小米","魅族","苹果","华为","一加","荣耀","Mate7","努比亚","OPPO","vivo","大神","乐视","小辣椒","P8","奇酷","锤子","金立"}; private ListView mListView; private Context mContext; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); mContext = this; mListView = (ListView) this.findViewById(R.id.mListView); MyAdapter mAdapter = new MyAdapter(mContext,data); mListView.setAdapter(mAdapter); }}
自定义适配器的代码:
package com.example.textviewtest;import android.content.Context;import android.view.View;import android.view.View.OnClickListener;import android.view.ViewGroup;import android.widget.BaseAdapter;import android.widget.Button;import android.widget.TextView;import android.widget.Toast;public class MyAdapter extends BaseAdapter{ private Context mContext; private String[] data; public MyAdapter(Context mContext, String[] data) { this.mContext = mContext; this.data = data; } @Override public int getCount() { // TODO Auto-generated method stub return data.length; } @Override public Object getItem(int position) { // TODO Auto-generated method stub return null; } @Override public long getItemId(int position) { // TODO Auto-generated method stub return 0; } @Override public View getView(final int position, View convertView, ViewGroup viewGroup) { View myView ; ItemViewHolder itemViewHolder; if(view == null) { myView = View.inflate(mContext, R.layout.my_adapter, null); itemViewHolder = new ItemViewHolder(); itemViewHolder.mTextView = (TextView) myView.findViewById(R.id.mTextView); itemViewHolder.mButton = (Button) myView.findViewById(R.id.mButton); myView.setTag(itemViewHolder); } else { myView = view; itemViewHolder = (ItemViewHolder) view.getTag(); } itemViewHolder.mTextView.setText(data[position]); itemViewHolder.mButton.setOnClickListener(new OnClickListener() { @Override public void onClick(View view) { Toast.makeText(mContext, data[position], Toast.LENGTH_SHORT).show(); } }); myView.setTag(itemViewHolder); return myView; } public class ItemViewHolder { public TextView mTextView; public Button mButton; }}
1、在适配器的构造函数中,我们将需要的数据源传入 2、利用Android的Recycler机制,利用convertView来重新回收View,避免每次都去创建新的View。 3、使用ViewHolder将需要缓存的view封装好,convertView的setTag就是将这些缓存起来供下次调用。因此,当第二次使用的时候只需要通过getTag()方法就可以获得ViewHolder对象