【Android】ListView控件总结

待我称王封你为后i 2022-02-26 17:50 387阅读 0赞

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
                }
            });
        }
    }

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzIwNjE3OTgz_size_16_color_FFFFFF_t_70][]

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;
        }
    }

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