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ListView 及适配器的应用

2022-05-04 12:31:18 作者：互联网

ListView的应用【包含Adapter的应用】

父容器和子view

【main_activity.xml】

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        android:fitsSystemWindows="true">
    <ListView
        android:id="@+id/lv_hobby"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>
</LinearLayout>

【hobby_item.xml】

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
        <RelativeLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="horizontal">
            <TextView
                android:id="@+id/hobby"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"/>
            <CheckBox
                android:id="@+id/checkbox"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_alignParentEnd="true"/>
        </RelativeLayout>
</LinearLayout>

item封装-->Hobby.java

package com.neostra.test;

public class Hobby {
    private String hobby;

    public Hobby(String hobby) {
        this.hobby = hobby;
    }

    public String getHobby() {
        return hobby;
    }

    public void setHobby(String hobby) {
        this.hobby = hobby;
    }

    @Override
    public String toString() {
        return "Hobby{" +
                "hobby='" + hobby + '\'' +
                '}';
    }
}

子view（hobby_item）适配器--->HobbyAdapter.java

package com.neostra.test;

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

import java.util.ArrayList;

public class HobbyAdapter extends BaseAdapter {
    private ArrayList<Hobby> dataList;//适配器数据源
    private Context mContext;

    public HobbyAdapter(ArrayList<Hobby> dataList, Context mContext) {
        this.dataList = dataList;
        this.mContext = mContext;
    }
//item长度
    @Override
    public int getCount() {
        return dataList.size();
    }

//item项
    @Override
    public Object getItem(int i) {
        return dataList.get(i);
    }

    @Override
    public long getItemId(int i) {
        return 0;
    }
//获取item，放回匹配的视图
    @Override
    public View getView(int i, View view, ViewGroup viewGroup) {
        MyViewHolder myViewHolder=null;//什么内部类Holder对象
        //判断xml视图是否已存在view当中
        if (view == null){
            view = View.inflate(mContext,R.layout.hobby_item,null);
            TextView hobby=view.findViewById(R.id.hobby);
            CheckBox checkedBox=view.findViewById(R.id.checkbox);
            myViewHolder = new MyViewHolder(hobby,checkedBox);
            view.setTag(myViewHolder);//将myViewHolder存储到view当中，从而不用getView时都新建子view中的控件
        }else {
            myViewHolder=(MyViewHolder) view.getTag();//若view不为空，则获取到子viewHolder类
        }
        myViewHolder.hobby.setText(dataList.get(i).getHobby());//动态设置子view显示效果
        return view;
    }
    //视图holder类
    static class MyViewHolder{
        private TextView hobby;
        private CheckBox checkBox;

        public MyViewHolder(TextView hobby, CheckBox checkBox) {
            this.hobby = hobby;
            this.checkBox = checkBox;
        }
    }
}

MainActivity.java

package com.neostra.test;

import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.DividerItemDecoration;
import androidx.recyclerview.widget.GridLayoutManager;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import android.os.Bundle;
import android.util.Log;
import android.widget.GridLayout;
import android.widget.GridView;
import android.widget.LinearLayout;
import android.widget.ListView;

import java.time.LocalDate;
import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {
    private ListView lv_honbby;
    private HobbyAdapter hobbyAdapter;
    private ArrayList<Hobby> dataList;//适配数据准备

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        dataList = new ArrayList<Hobby>();//数据源准备
        dataList.add(new Hobby("math"));
        dataList.add(new Hobby("English"));
        dataList.add(new Hobby("chinese"));
        dataList.add(new Hobby("chinese"));
        lv_hobby = findViewById(R.id.lv_hobby);
        hobbyAdapter = new HobbyAdapter(dataList, this);//适配器准备
        lv_hobby.setAdapter(hobbyAdapter);//为listview视图设置适配器
    }

}

标签：layout,dataList,适配器,应用,import,hobby,android,ListView,view
来源： https://www.cnblogs.com/a-n-yan/p/16220796.html