Android 自定义适配器

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