listview

activity_main.xml

package com.example.listview;

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<Bean> data;
    private Context context;

    public MyAdapter(List<Bean> data, Context context) {
        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 = null;
        if (view==null) {
            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("leo","getView"+i);
        return view;


    }
    private  final class  ViewHolder{
        TextView textView;
    }
}

list_item.xml

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


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

Bean

package com.example.listview;

public class Bean {
    String name;

    public String getName() {
        return name;
    }

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

MainActivity

package com.example.listview;

import androidx.appcompat.app.AppCompatActivity;

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("想学"+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("leo", "onItemClick: "+i );
            }
        });
    }
}

MyAdapter

package com.example.listview;

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<Bean> data;
    private Context context;

    public MyAdapter(List<Bean> data, Context context) {
        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 = null;
        if (view==null) {
            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("leo","getView"+i);
        return view;


    }
    private  final class  ViewHolder{
        TextView textView;
    }
}