Android Studio（十一）-ListView列表

activity_main.xml

list_item.xml

Bean.java

package com.example.myapplication;

public class Bean {
    String name;

    public String getName() {
        return name;
    }

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

MainActivity.java

package com.example.myapplication;

import androidx.appcompat.app.alertDialog;
import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.Toolbar;
import androidx.core.app.NotificationCompat;

import android.app.Notification;
import android.app.NotificationChannel;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.DialogInterface;
import android.content.Intent;
import android.graphics.BitmapFactory;
import android.graphics.Color;
import android.media.audiofx.DynamicsProcessing;
import android.nfc.Tag;
import android.os.Build;
import android.os.Bundle;
import android.provider.FontsContract;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.PopupMenu;
import android.widget.PopupWindow;
import android.widget.ProgressBar;
import android.widget.TextView;


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

import javax.security.auth.login.LoginException;

public class MainActivity extends AppCompatActivity {
    private List data = new ArrayList<>();
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);//R文件自动生成，不可修改，创建的资源都会在R文件中生成一个索引

        for(int i=0;i<100;i++)
        {
            Bean bean=new Bean();
            bean.setName("zhang"+i);
            data.add(bean);
        }

        ListView listView = findViewById(R.id.lv);
        listView.setAdapter(new MyAdapter(data,this));
        listView.setonItemClickListener(new AdapterView.onItemClickListener() {
            @Override
            public void onItemClick(AdapterView adapterView, View view, int i, long l) {
                Log.e("lala", "onItemClick: "+i);
            }
        });
    }

}

MyAdapter.java

adapter是view和数据的桥梁。在ListView中，不可能手动给每一个格子都新建一个view，Adapter会帮你自动绘制view并且填充数据。

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 java.util.List;

public class MyAdapter extends baseAdapter {

    private List data;
    private Context context;

    public MyAdapter(List data, Context context) {//构造方法，快捷键自动生成
        this.data = data;
        this.context = context;
    }

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

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

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

    @Override
    public View getView(int i, View view, ViewGroup viewGroup) {
        ViewHolder viewHolder;
        if(view==null)
        {
            viewHolder = new ViewHolder();
//ViewHolder通常出现在适配器里，为的是listview滚动的时候快速设置值，而不必每次都重新创建很多对象，从而提升性能
            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();
        }
        viewHolder.textView.setText(data.get(i).getName());
        Log.e("la", "getView: "+i );
        return view;
    }
    private final class ViewHolder{
        TextView textView;
    }
}