十六、ListView

一.、使用 setAdapter 方法进行 内容的填充

二、 创建  MyAdapter 类继承 BaseAdapter ；对 BaseAdapter 的方法 getView 进行重写，进行信息的展示

三、代码示例

1.设置页面

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:android="http://schemas.android.com/apk/res/android">

    <ListView
        android:id="@+id/lv"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

</LinearLayout>

　　

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    xmlns:android="http://schemas.android.com/apk/res/android">

    <TextView
        android:id="@+id/tv"
        android:textSize="30sp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>

</LinearLayout>

　　2.后台

package com.example.myapplication;

public class Bean {
    String name;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

　　

package com.example.myapplication;

import androidx.appcompat.app.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;

import android.content.Context;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListView;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    private List<Bean> data = new ArrayList<>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        for(int i=0 ; i<100 ; i++){
            Bean bean=new Bean();
            bean.setName("乡学"+i);
            data.add(bean);
        }
        Context context=this;
        ListView listView=findViewById(R.id.lv);
        listView.setAdapter(new MyAdapter(data,context));

        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
                Log.e("leo", "onItemClick: "+i );

                //显示对话框
                AlertDialog.Builder builder=new AlertDialog.Builder(context);
                builder.setIcon(R.mipmap.ic_launcher)
                        .setTitle("标题")
                        .setMessage("文本提示信息："+data.get(i).getName())
                        .create().show();
            }
        });

    }
}

　　

package com.example.myapplication;

import android.content.Context;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;

import org.w3c.dom.Text;

import java.util.List;

public class MyAdapter extends BaseAdapter {

    private List<Bean> data;
    private Context context;

    public MyAdapter(List<Bean> data2,Context context2){
        this.data=data2;
        this.context=context2;
    }

    @Override
    public int getCount() {
        return data.size();
    }

    @Override
    public Object getItem(int i) {
        return null;
    }

    @Override
    public long getItemId(int i) {
        return i;
    }

    /**
     * 返回item条目
     * */
    @Override
    public View getView(int i, View view, ViewGroup viewGroup) {
        ViewHolder viewHolder;

        //当view等于null时进行创建
        if (view==null) {
            viewHolder=new ViewHolder();
            view = LayoutInflater.from(context).inflate(R.layout.list_item, viewGroup, false);
            viewHolder.textView = view.findViewById(R.id.tv);
            view.setTag(viewHolder);
        }
        else{
            viewHolder=(ViewHolder)view.getTag();
        }

        //显示信息打印并返回
        viewHolder.textView.setText(data.get(i).getName());
        Log.e("leo", "getView:打印 " + i);
        return view;
    }

    private  final  class  ViewHolder{
        TextView textView;
    }


}