Android_ListView与GridView练习

需求分析

请用ListView和自定义Adapter实现下列页面（可以自行设计并添加元素，以丰富该页面） :

（1）界面元素如图1所示，内容可以比图1更丰富
（2）实现图1的界面列表和操作栏（Toolbar）
（3）点击任意列表项，出现第二个页面，如图2所示（点击了“北京市”，出现北京市所有区的页面)

（4）图2的内容请用GridView和自定义的Adapter实现。
（5）实现图2 的Toolbar。

这里我反复看了几次，这里的toolbar只要求设置一个样式而已，并不用编写什么实质的功能，重点是listview和gridview的实现，和两个页面界面间交互

设计

界面一布局文件的设计

因为toolbar和actionbar互相冲突会造成闪退,首先要在themes.xml主题布局文件中设置一个NoActionBar的style，这里项目规模比较小，我们把默认所以Activity采用主题style直接改成改成NoActionBar。

<resources xmlns:tools="http://schemas.android.com/tools">
    <!-- Base application theme. -->
    <style name="Theme.Test6" parent="Theme.MaterialComponents.DayNight.NoActionBar">
        <!-- Primary brand color. -->
        <item name="colorPrimary">@color/purple_500</item>
        <item name="colorPrimaryVariant">@color/purple_700</item>
        <item name="colorOnPrimary">@color/white</item>
        <!-- Secondary brand color. -->
        <item name="colorSecondary">@color/teal_200</item>
        <item name="colorSecondaryVariant">@color/teal_700</item>
        <item name="colorOnSecondary">@color/black</item>
        <!-- Status bar color. -->
        <item name="android:statusBarColor" tools:targetApi="l">?attr/colorPrimaryVariant</item>
        <!-- Customize your theme here. -->
    </style>
</resources>

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <androidx.appcompat.widget.Toolbar
        android:id="@+id/ma_tb"
        android:layout_width="match_parent"
        android:layout_height="?actionBarSize"
         android:background="#2196F3"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintStart_toStartOf="parent"/>

    <ListView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/ma_lv"
        app:layout_constraintTop_toBottomOf="@id/ma_tb"
        android:choiceMode="singleChoice"
        app:layout_constraintStart_toStartOf="parent"/>
</androidx.constraintlayout.widget.ConstraintLayout>

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <TextView
        android:id="@+id/item_tv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="测试"
        android:layout_marginTop="5dp"
        android:gravity="center"
        android:layout_marginStart="40dp"
        android:textSize="30sp"
        app:layout_constraintEnd_toStartOf="@+id/item_iv"
        app:layout_constraintStart_toStartOf="parent"

        app:layout_constraintTop_toTopOf="parent" />

    <ImageView
        android:layout_marginStart="10dp"
        android:id="@+id/item_iv"
        android:layout_width="128px"
        android:layout_height="128px"
        app:layout_constraintStart_toEndOf="@id/item_tv"
        app:layout_constraintTop_toTopOf="parent"
        />

</androidx.constraintlayout.widget.ConstraintLayout>

界面一功能实现

这里我们本应该设计省份和城市作为两个实体类，区分开两个列表的，但是这是个练习，为了减少重复的无用代码，我们把城市和省份都复用City实体类
这里写了两个构造函数，分别给有图的省份和无图的城市使用

package com.gallifrey.test6;

public class City {
    private String name;
    private int imageId;

    public City(String name, int imageId) {
        this.name = name;
        this.imageId = imageId;
    }

    public City(String  name) {
        this.name=name;
    }

    public String getName() {
        return name;
    }

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

    public int getImageId() {
        return imageId;
    }

    public void setImageId(int imageId) {
        this.imageId = imageId;
    }
}

package com.gallifrey.test6;

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

import androidx.recyclerview.widget.RecyclerView;

import java.util.LinkedList;

public class CityAdapter extends BaseAdapter {
    private LinkedList<City> data;
    private Context context;

    public CityAdapter(LinkedList<City> data, Context context) {
        this.data = data;
        this.context = context;
    }

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

    @Override
    public Object getItem(int i) {
        return data.get(i);
    }

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

    @Override
    public View getView(int i, View view, ViewGroup viewGroup) {
        ViewHolder viewHolder=null;
        if(view==null){
            //动态创建
            view= LayoutInflater.from(context).inflate(R.layout.listitem,viewGroup,false);
            viewHolder=new ViewHolder();
            viewHolder.imageView=view.findViewById(R.id.item_iv);
            viewHolder.textView=view.findViewById(R.id.item_tv);
            view.setTag(viewHolder);
        }else{
            viewHolder= (ViewHolder) view.getTag();
        }
        //设置数据
        viewHolder.textView.setText(data.get(i).getName());
        viewHolder.imageView.setImageResource(data.get(i).getImageId());


        return view;
    }

    //用ViewHolder优化代码
    static class ViewHolder {
        private ImageView imageView;
        private TextView textView;
    }
}

这里要注意toolbar引入的类是androidx.appcompat.widget.Toolbar，弄错就闪退了，另外前面的NoActionbar没有设置也是会闪退的。
当然因为的toolbar没有什么实质功能，这个toolbar的菜单图标，你在xml中用imageview加上图标也是可以的。
这里我们跳转页面前先设置一个变量，这样我们在跳转页面二时能加载对应的数据

package com.gallifrey.test6;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListView;
import androidx.appcompat.widget.Toolbar;

import java.util.LinkedList;

public class MainActivity extends AppCompatActivity {
    public static int whichCity=0;
    private LinkedList<City> cityLinkedList;
    private Toolbar toolbar;
    private ListView mlv;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        toolbar=findViewById(R.id.ma_tb);
        mlv=findViewById(R.id.ma_lv);


        toolbar.setTitle("城市管理");
        setSupportActionBar(toolbar);


        //初始化数据
        initCity();
        //设置adapter
        mlv.setAdapter(new CityAdapter(cityLinkedList,this));

        //设置监听实现页面二的跳转
        mlv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
                Intent intent=new Intent(MainActivity.this,SecondActivity.class);
                whichCity=i;//标记哪一个省份被点击了，让页面二加载对应的gridview数据
                startActivity(intent);
            }
        });


    }

    //设置toolbar菜单
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.toolbar_menu,menu);
        return super.onCreateOptionsMenu(menu);
    }


    //初始化省份列表
    private void initCity() {
        cityLinkedList=new LinkedList<>();
        cityLinkedList.add(new City("北京市",R.drawable.beijing));
        cityLinkedList.add(new City("上海市",R.drawable.shanghai));
        cityLinkedList.add(new City("湖北省",R.drawable.hubei));
        cityLinkedList.add(new City("浙江省",R.drawable.zhengjiang));
        cityLinkedList.add(new City("广东省",R.drawable.guangdong));
        cityLinkedList.add(new City("江苏省",R.drawable.jiangsu));
        cityLinkedList.add(new City("安徽省",R.drawable.anhui));
        cityLinkedList.add(new City("湖南省",R.drawable.hunan));

    }


}

界面二布局文件的设计

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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="match_parent"
    android:layout_height="match_parent"
    tools:context=".SecondActivity">
    <androidx.appcompat.widget.Toolbar
        android:id="@+id/sa_tb"
        android:layout_width="match_parent"
        android:layout_height="?actionBarSize"
        android:background="#2196F3"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintStart_toStartOf="parent">
        <TextView
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:textSize="25sp"
            android:text="添加城市"
            android:textColor="@color/white"
            android:gravity="center"
            />
    </androidx.appcompat.widget.Toolbar>

    <GridView
        android:id="@+id/sa_gv"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:layout_constraintTop_toBottomOf="@id/sa_tb"
        android:numColumns="4"
        android:horizontalSpacing="10dp"
        app:layout_constraintStart_toStartOf="parent"/>


</androidx.constraintlayout.widget.ConstraintLayout>

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:app="http://schemas.android.com/apk/res-auto">
    <TextView
        android:layout_margin="10dp"
        android:id="@+id/gridview_item_tv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:padding="10dp"
        android:gravity="center"
        android:text="测一"

        android:textSize="20sp"
        android:background="@drawable/radius"

        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        />

</androidx.constraintlayout.widget.ConstraintLayout>

在drawable目录下添加一个的圆角样式

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <corners android:radius="10dp"/>
    <solid android:color="#89C9E6"></solid>
</shape>

页面二功能实现

package com.gallifrey.test6;

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

import java.util.LinkedList;

public class GridViewCityAdapter extends BaseAdapter {
    private LinkedList<City> data;
    private Context context;

    public GridViewCityAdapter(LinkedList<City> data, Context context) {
        this.data = data;
        this.context = context;
    }

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

    @Override
    public Object getItem(int i) {
        return data.get(i);
    }

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

    @Override
    public View getView(int i, View view, ViewGroup viewGroup) {
       ViewHolder viewHolder=null;
        if(view==null){
            //动态创建
            view= LayoutInflater.from(context).inflate(R.layout.gridview_listitem,viewGroup,false);
            viewHolder=new ViewHolder();
            viewHolder.textView=view.findViewById(R.id.gridview_item_tv);
            view.setTag(viewHolder);
        }else{
            viewHolder= (ViewHolder) view.getTag();
        }
        //设置数据
        viewHolder.textView.setText(data.get(i).getName());



        return view;
    }

    //用ViewHolder优化代码
    static class ViewHolder {
        private TextView textView;
    }
}

这里利用页面一Activity实现跳转时的变量来决定加载哪些城市数据
因为城市太多了，我这里每个省份都只写了七个城市

package com.gallifrey.test6;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.widget.GridView;

import java.util.LinkedList;

public class SecondActivity extends AppCompatActivity {
    private LinkedList<City> cityLinkedList;
    private GridView gridView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second);

        gridView=findViewById(R.id.sa_gv);
        //初始化数据
        initCity(MainActivity.whichCity);
        //设置adapter
        gridView.setAdapter(new GridViewCityAdapter(cityLinkedList,this));



    }

    //通过传入省份号来初始化城市列表
    private void initCity(int whichCity) {
        switch (whichCity){
            case 0:
                cityLinkedList=new LinkedList<>();
                cityLinkedList.add(new City("东城区"));
                cityLinkedList.add(new City("西城区"));
                cityLinkedList.add(new City("朝阳区"));
                cityLinkedList.add(new City("丰台区"));
                cityLinkedList.add(new City("石景山"));
                cityLinkedList.add(new City("海淀区"));
                cityLinkedList.add(new City("顺义区"));
                cityLinkedList.add(new City("通州区"));
                cityLinkedList.add(new City("大兴区"));
                break;
            case 1:
                cityLinkedList=new LinkedList<>();
                cityLinkedList.add(new City("黄埔区"));
                cityLinkedList.add(new City("徐汇区"));
                cityLinkedList.add(new City("长宁区"));
                cityLinkedList.add(new City("静安区"));
                cityLinkedList.add(new City("普陀山"));
                cityLinkedList.add(new City("虹口区"));
                cityLinkedList.add(new City("杨浦区"));
                break;

            case 2:
                cityLinkedList=new LinkedList<>();
                cityLinkedList.add(new City("武汉市"));
                cityLinkedList.add(new City("黄氏市"));
                cityLinkedList.add(new City("十堰市"));
                cityLinkedList.add(new City("宜昌市"));
                cityLinkedList.add(new City("襄阳市"));
                cityLinkedList.add(new City("鄂州市"));
                cityLinkedList.add(new City("黄冈市"));
                break;
            case 3:
                cityLinkedList=new LinkedList<>();
                cityLinkedList.add(new City("杭州市"));
                cityLinkedList.add(new City("宁波市"));
                cityLinkedList.add(new City("温州市"));
                cityLinkedList.add(new City("嘉兴市"));
                cityLinkedList.add(new City("湖州市"));
                cityLinkedList.add(new City("绍兴市"));
                cityLinkedList.add(new City("金华市"));
                break;
            case 4:
                cityLinkedList=new LinkedList<>();
                cityLinkedList.add(new City("广州市"));
                cityLinkedList.add(new City("韶关市"));
                cityLinkedList.add(new City("佛山市"));
                cityLinkedList.add(new City("珠海市"));
                cityLinkedList.add(new City("汕头市"));
                cityLinkedList.add(new City("江门市"));
                cityLinkedList.add(new City("湛江市"));
                break;
            case 5:
                cityLinkedList=new LinkedList<>();
                cityLinkedList.add(new City("南京市"));
                cityLinkedList.add(new City("无锡市"));
                cityLinkedList.add(new City("徐州市"));
                cityLinkedList.add(new City("常州市"));
                cityLinkedList.add(new City("苏州市"));
                cityLinkedList.add(new City("南通市"));
                cityLinkedList.add(new City("淮安市"));
                break;
            case 6:
                cityLinkedList=new LinkedList<>();
                cityLinkedList.add(new City("合肥市"));
                cityLinkedList.add(new City("芜湖市"));
                cityLinkedList.add(new City("蚌埠市"));
                cityLinkedList.add(new City("淮南市"));
                cityLinkedList.add(new City("淮北市"));
                cityLinkedList.add(new City("安庆市"));
                cityLinkedList.add(new City("铜陵市"));
                break;
            case 7:
                cityLinkedList=new LinkedList<>();
                cityLinkedList.add(new City("长沙市"));
                cityLinkedList.add(new City("株洲市"));
                cityLinkedList.add(new City("湘潭市"));
                cityLinkedList.add(new City("衡阳市"));
                cityLinkedList.add(new City("昭阳市"));
                cityLinkedList.add(new City("岳阳市"));
                cityLinkedList.add(new City("杨永州"));
                break;
        }

    }

}