【Android】ListView控件总结
ListView控件是列表视图展示，排列方式是纵向。其中ListView控件有自己默认的布局，当默认布局不能满足我们要求时，我们可以进行自定义控件，下面我们详细分析ListView控件的使用。
一、默认效果
思路：在layout下创建一个布局，添加ListView控件，在Activity中对ListView控件赋值，其中ListView的方法setAdapter起了举足轻重的作用，而setAdapter（）方法中需要传入一个adapter类型的数据，从此可以进入了童话世界。
其中官方解释文档是这样说的：
/**
* Sets the data behind this ListView.
*
* The adapter passed to this method may be wrapped by a {@link WrapperListAdapter},
* depending on the ListView features currently in use. For instance, adding
* headers and/or footers will cause the adapter to be wrapped.
*
* @param adapter The ListAdapter which is responsible for maintaining the
* data backing this list and for producing a view to represent an
* item in that data set.
*
* @see #getAdapter()
*/其大意是：这个适配器通过这个方法可以封装成你具有你自己特点的ListView控件
Activity详解
package com.first.tglistviewdemo.ListViewDefault;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v7.app.ActionBar;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Adapter;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;
import com.first.tglistviewdemo.R;
public class ListViewDefaultActivity extends AppCompatActivity {
private ListView lv;
private String[] fruit = {
"apple",
"pear",
"Orange",
"Cherry",
"Mango",
"apple",
"pear",
"Orange",
"Cherry",
"Mango",
"apple",
"pear",
"Orange",
"Cherry",
"Mango",
"apple",
"pear",
"Orange",
"Cherry",
"Mango"
};
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_listview_default);
lv = findViewById(R.id.lv_1);
ArrayAdapter arrayAdapter = new ArrayAdapter(ListViewDefaultActivity.this, android.R.layout.simple_list_item_1, fruit);
lv.setAdapter(arrayAdapter); //
//修改标题栏
ActionBar actionBar = getSupportActionBar();
if (actionBar != null) {
actionBar.setTitle("默认的ListView样式");
}
//点击事件
lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
Toast.makeText(ListViewDefaultActivity.this,"position"+position+":"+fruit[position]+",id"+id,Toast.LENGTH_SHORT).show();
}
});
lv.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
@Override
public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) {
Toast.makeText(ListViewDefaultActivity.this,"position"+position+":"+fruit[position]+",id"+id,Toast.LENGTH_SHORT).show();
return true; //fasle 长按点击回调函数不会销毁，会继续执行click true:长按回调函数将销毁
}
});
}
}
二、自定义效果
自定义效果只不过在setAdapter（）方法中的参数动了下手脚
思路：我们创建一个adapter的子类，其所有的adapter都是继承自BaseAdapter的，同样的我们只要继承一个其adapter类即可。
/**
* Get a View that displays the data at the specified position in the data set. You can either
* create a View manually or inflate it from an XML layout file. When the View is inflated, the
* parent View (GridView, ListView...) will apply default layout parameters unless you use
* {@link android.view.LayoutInflater#inflate(int, android.view.ViewGroup, boolean)}
* to specify a root view and to prevent attachment to the root.
*
* @param position The position of the item within the adapter's data set of the item whose view
* we want.
* @param convertView The old view to reuse, if possible. Note: You should check that this view
* is non-null and of an appropriate type before using. If it is not possible to convert
* this view to display the correct data, this method can create a new view.
* Heterogeneous lists can specify their number of view types, so that this View is
* always of the right type (see {@link #getViewTypeCount()} and
* {@link #getItemViewType(int)}).
* @param parent The parent that this view will eventually be attached to
* @return A View corresponding to the data at the specified position.
*/官方是这样解释的：在数据集中得到一个子列，你同样可以创建一个视图或者填充这个视图来之XML布局，当这个视图控件被填充，将会提供一个默认的布局样式，除非你用了一个自己的布局
package com.first.tglistviewdemo.ListViewDefault;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;
import android.widget.Toast;
import com.first.tglistviewdemo.R;
import java.util.List;
public class LvdAdapter extends ArrayAdapter<Fruit> {
private int resourceid;
public LvdAdapter(Context context, int resourceViewId, List<Fruit> data) {
super(context, resourceViewId,data);
resourceid=resourceViewId;//当前自己构造的Layout布局的ID
}
static class ViewHolder{
private TextView fname;
private TextView price;
private TextView protime;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
Fruit fruit=getItem(position);
Toast.makeText(getContext(),fruit.getFname(),Toast.LENGTH_SHORT).show();
ViewHolder viewHolder;
if(convertView==null){
convertView= LayoutInflater.from(getContext()).inflate(resourceid,null);
viewHolder=new ViewHolder();
viewHolder.fname= convertView.findViewById(R.id.txt_fname);
viewHolder.price=convertView.findViewById(R.id.txt_price);
viewHolder.protime=convertView.findViewById(R.id.txt_protime);
convertView.setTag(viewHolder);
}else{
convertView=convertView;
viewHolder= (ViewHolder) convertView.getTag();
}
viewHolder.fname.setText(fruit.getFname());
viewHolder.protime.setText(fruit.getPrice());
viewHolder.price.setText(fruit.getPrice());
return convertView;
}
}