ListView

效果图

1、在activity_main.xml中创建ListView，再创建list_item.xml

2、MainActivity.java

package com.example.myapplication;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListView;
import androidx.appcompat.app.AppCompatActivity;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends AppCompatActivity {
    private List data = new ArrayList();
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
//       每个item显示的内容
        for (int i = 0; i  
3、创建Bean类
 
package com.example.myapplication;
public class Bean {
    String name;
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
}
 
4、创建一个适配器MyAdapter
 
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) {
        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) {
        if (view == null) {
            view = LayoutInflater.from(context).inflate(R.layout.list_item,viewGroup,false);
        }
        TextView textView = view.findViewById(R.id.tv);
        textView.setText(data.get(i).getName());
        Log.e("leo","getView" + i);
        return view;
    }
}
 
 
上述标红处需重点理解
 
5、使用ViewHolder优化适配器
 
降低findViewById的使用，提高运行速度
 
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) {
        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();
            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;
    }
}