GirdView练习作业

案例一：

MainActivity布局文件：

xml version="1.0" encoding="utf-8"?>
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"
    android:orientation="vertical"
    tools:context="com.mrzhao.exam1demo.MainActivity">

            android:id="@+id/gridView"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"
        android:numColumns="3">

            android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="10dp"
        android:onClick="onClick" />

MainActivity文件：

public class MainActivity extends AppCompatActivity {

    private GridView girdView;
    private List entities = new ArrayList<>();
    private Gson gson;
    private  MyAdapter myAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        girdView = (GridView) findViewById(R.id.gridView);
        // 初始化数据
        initData();
        gson = new Gson();
        // 转成 json
        String json = gson.toJson(entities);
        // 解析数组
        Type type = new TypeToken>() {
        }.getType();
        entities = gson.fromJson(json, type);
        //创建适配器
        myAdapter =new MyAdapter(entities,this);
        girdView.setAdapter(myAdapter);
    }

    private void initData() {
        CustomEntity en1 = new CustomEntity("图片1", R.mipmap.ic_launcher);
        CustomEntity en2 = new CustomEntity("阿苏", R.mipmap.aaa);
        CustomEntity en3 = new CustomEntity("请问", R.mipmap.bbb);
        CustomEntity en4 = new CustomEntity("是 v 的", R.mipmap.ccc);
        CustomEntity en5 = new CustomEntity("儿童", R.mipmap.aaa);
        CustomEntity en6 = new CustomEntity("表示层v", R.mipmap.bbb);
        CustomEntity en7 = new CustomEntity("沃尔特", R.mipmap.ccc);
        CustomEntity en8 = new CustomEntity("电饭锅", R.mipmap.ic_launcher_round);
        CustomEntity en9 = new CustomEntity("体育", R.mipmap.ccc);
        CustomEntity en10 = new CustomEntity("体育", R.mipmap.aaa);

        entities.add(en1);
        entities.add(en2);
        entities.add(en3);
        entities.add(en4);
        entities.add(en5);
        entities.add(en6);
        entities.add(en7);
        entities.add(en8);
        entities.add(en9);
        entities.add(en10);
    }

    public void onClick(View view) {
        //模拟添加十条数据
        initData();
        // 刷新
        myAdapter.notifyDataSetChanged();
    }
}

适配器：

public class MyAdapter extends BaseAdapter {
    private List list ;
    private Context context;
    private LayoutInflater inflater;

    public MyAdapter(List list, Context context) {
        this.list = list;
        this.context = context;
        inflater =  LayoutInflater.from(context);
    }

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

    @Override
    public Object getItem(int position) {
        return list.get(position);
    }

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

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder holder = new ViewHolder();
        if (convertView == null){
            convertView =  inflater.inflate(R.layout.item_layout,parent,false);
            holder = new ViewHolder();
            holder.imegView =  convertView.findViewById(R.id.imageView);
            holder.textView =  convertView.findViewById(R.id.textView);
            convertView.setTag(holder);
        }else {
            holder = (ViewHolder) convertView.getTag();
        }

        CustomEntity customEntity = list.get(position);
        holder.textView.setText(customEntity.getInfo());
        holder.imegView.setImageResource(customEntity.getImg());
        return convertView;
    }
    static  class ViewHolder{
        ImageView imegView;
        TextView  textView;
    }
}

条目布局：

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

            android:id="@+id/imageView"
        android:layout_width="100dp"
        android:layout_height="100dp" />

            android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="10dp"
        android:textSize="20sp" />

实体类文件：

public class CustomEntity {
    private String info;
    private int img;

    public CustomEntity(String info, int img) {
        this.info = info;
        this.img = img;
    }

    @Override
    public String toString() {
        return "CustomEntity{" +
                "info='" + info + '\'' +
                ", img=" + img +
                '}';
    }

    public String getInfo() {
        return info;
    }

    public void setInfo(String info) {
        this.info = info;
    }

    public int getImg() {
        return img;
    }

    public void setImg(int img) {
        this.img = img;
    }
}

案例二：

MainActivity布局文件：

xml version="1.0" encoding="utf-8"?>
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="com.mrzhao.exam2demo.MainActivity">

            android:id="@+id/gridView"
        android:layout_width="match_parent"
        android:horizontalSpacing="2dp"
        android:verticalSpacing="2dp"
        android:layout_height="match_parent"
        android:numColumns="3">

MainActivity文件：

public class MainActivity extends AppCompatActivity {

    private GridView gridView;
    private List list = new ArrayList<>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        gridView = (GridView) findViewById(R.id.gridView);
        list.add("重庆");
        list.add("上海");
        list.add("广东");
        list.add("成都");
        list.add("西安");
        list.add("厦门");
        list.add("合肥");
        list.add("银川");
        list.add("广西");
        MyAdapter myAdapter = new MyAdapter(list, this);
        gridView.setAdapter(myAdapter);
        gridView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView parent, View view, int position, long id) {
                Toast.makeText(MainActivity.this, list.get(position), Toast.LENGTH_SHORT).show();
            }
        });
    }
}

适配器：

public class MyAdapter extends BaseAdapter {
    private List list;
    private Context context;
    private LayoutInflater inflater;
    private int[] bg = {Color.BLACK, Color.BLUE, Color.CYAN, Color.DKGRAY, Color.GRAY, Color.GREEN, Color.LTGRAY, Color.MAGENTA, Color.RED};

    public MyAdapter(List list, Context context) {
        this.list = list;
        this.context = context;
        inflater = LayoutInflater.from(context);
    }

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

    @Override
    public Object getItem(int position) {
        return list.get(position);
    }

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

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder holder = new ViewHolder();
        if (convertView == null) {
            convertView = inflater.inflate(R.layout.item_layout, parent, false);
            holder = new ViewHolder();
            holder.textView = convertView.findViewById(R.id.textView);
            convertView.setTag(holder);
        } else {
            holder = (ViewHolder) convertView.getTag();
        }


        holder.textView.setText(list.get(position));
        convertView.setBackgroundColor(bg[position]);
        return convertView;
    }

    static class ViewHolder {
        TextView textView;
    }
}

条目布局：

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

            android:id="@+id/textView"
        android:layout_marginTop="50dp"
        android:layout_marginBottom="50dp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="20sp" />