17.ListView安卓开发基本布局

一、实现的步骤

1.封装数据

2.创建数据对应的实例，放入list

3.用for循环打印封装的数据

4.绑定listview控件

5.创建适配器，继承BaseAdapter，将数据放入适配器

6.创建构造方法，将该数据和上下文放入MyAdapter内

7.在单元格布局方法内，将布局放入

8.设置点击方法，点点击某个条目之后，显示对应的消息提醒

二、总体实现代码

1.布局activity_main.xml文件

<?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"
    >
    <ListView
        android:id="@+id/lv_item"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        />
</LinearLayout>

2.布局list_item.xml文件

<?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="110dp"
    android:orientation="vertical"
    >
    <TextView
        android:id="@+id/tv_text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text=""
        android:lines="2"
        android:ellipsize="end"
        android:textSize="25dp"
        android:padding="8dp"
        android:textColor="#A81C122C"
        />
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:gravity="end"
        >
        <TextView
            android:id="@+id/tv_date"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text=""
            android:textSize="18dp"
            android:layout_marginRight="15dp"
            android:textColor="#E62A50"
            />
        <TextView
            android:id="@+id/tv_time"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="16:55"
            android:textSize="18dp"
            android:layout_marginRight="8dp"
            android:textColor="#E62A50"
            />
    </LinearLayout>
</LinearLayout>

3.StudyDataBean文件代码

package com.example.mylistview.bean;
public class StudyDataBean {
    //1.定义数据，从网上获取该数据（封装）
    private String name;
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
}

4.MainActivity文件代码

package com.example.mylistview;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListView;
import android.widget.Toast;
import com.example.mylistview.adapter.MyAdapter;
import com.example.mylistview.bean.StudyDataBean;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends AppCompatActivity {
    //2.创建数据实例
    private List<StudyDataBean> list=new ArrayList<>();
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //5.绑定该ListView的控件
        ListView lv_item = findViewById(R.id.lv_item);
        //3.利用for循环打印该数据
        for (int i=0;i<50;i++){
            //4.创建该封装的实例，将该数据放进list
            StudyDataBean studyDataBean=new StudyDataBean();
            studyDataBean.setName("学习"  + i);
            list.add(studyDataBean);
        }
        //7.将数据放进适配器
        lv_item.setAdapter(new MyAdapter(list,this));
        //15.设置点击方法，当点击到某个item，即弹出消息提醒
        lv_item.setOnItemClickListener(new AdapterView.OnItemClickListener() {
         @Override
         public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
         Toast.makeText(MainActivity.this, "点击了学习" +position, Toast.LENGTH_SHORT).show();
            }
        });
    }
}

5.MyAdapter文件代码

package com.example.mylistview.adapter;
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 com.example.mylistview.R;
import com.example.mylistview.bean.StudyDataBean;
import java.util.List;
  //6.创建辅助类，通过继承，实现每个方法
public class MyAdapter extends BaseAdapter {
    //8.创建构造方法，将数据源和上下文放入MyAdapter内
    private List<StudyDataBean> list;
    private Context context;
    public MyAdapter(List<StudyDataBean> list, Context context) {
        this.list = list;
        this.context = context;
    }
    //9.打印条数，是数据的长度
    @Override
    public int getCount() {
        return list.size();
    }
    @Override
    public Object getItem(int position) {
        return null;
    }
    //10.id就是对应数据的位置
    @Override
    public long getItemId(int position) {
        return position;
    }
    //11.返回每一个条目
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        /*
        12.将布局渲染给convertView，因为convertView会复用，为了防止不断创建，
        所以进行一个判断，通过判断，若该单元格布局为空，则显示该布局，
         */
        if (convertView==null) {
       convertView = LayoutInflater.from(context).inflate(R.layout.list_item, parent, false);
        }
        //13.通过控件绑定拿到单元格布局内的控件
        TextView tv_item = convertView.findViewById(R.id.tv_item);
        //14.获取该item的值
        tv_item.setText(list.get(position).getName());
        Log.e("he","getView:"+position);
        return convertView;
    }
}

6.效果图<br />![image.png](https://cdn.nlark.com/yuque/0/2021/png/1574587/1622281511907-2641bfbd-4007-4fc2-ab3d-8fffcaa02643.png#clientId=u7c22ae1d-9747-4&from=paste&height=565&id=ufea9d23a&margin=%5Bobject%20Object%5D&name=image.png&originHeight=565&originWidth=860&originalType=binary&size=111192&status=done&style=none&taskId=u287b0981-de49-4743-8e93-cf582e6cbcc&width=860)