GridView练习题

package com.example.wang.myapplication;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;

import java.util.ArrayList;
import java.util.List;

public class Main2Activity extends AppCompatActivity {

    GridView gv_1;
    List<MyClass> lm;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);
        gv_1=(GridView)findViewById(R.id.gv_1);

        lm=new ArrayList<MyClass>();

        MyClass myClass=new MyClass(R.drawable.f1,"名称1");

        lm.add(myClass);
        lm.add(new MyClass(R.drawable.f2,"名称2"));

        lm.add(new MyClass(R.drawable.f3,"名称3"));

        lm.add(new MyClass(R.drawable.f4,"名称4"));

        lm.add(new MyClass(R.drawable.f5,"名称5"));

        lm.add(new MyClass(R.drawable.f6,"名称6"));

        lm.add(new MyClass(R.drawable.f7,"名称7"));

        lm.add(new MyClass(R.drawable.f8,"名称8"));

        lm.add(new MyClass(R.drawable.f9,"名称9"));

        lm.add(new MyClass(R.drawable.f10,"名称10"));

        lm.add(new MyClass(R.drawable.f10,"名称1111"));

        lm.add(new MyClass(R.drawable.f10,"名称11"));
        
        GridAdapter gridAdapter=new GridAdapter();

        gv_1.setAdapter(gridAdapter);

    }

    class GridAdapter extends BaseAdapter
    {
        @Override
        public int getCount() {
            return lm.size();
        }

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

        @Override
        public long getItemId(int position) {
            return 0;
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {

            MyClass myClass=lm.get(position);

            if (convertView==null)
            {
                Log.e("TAG", "适配器 getView=" + position);
                convertView=View.inflate(Main2Activity.this,R.layout.activity_main21,null);
            }
            ImageView imageView=(ImageView)convertView.findViewById(R.id.iv_1);

            imageView.setImageResource(myClass.getImg());

            TextView textView=(TextView)convertView.findViewById(R.id.tv_1);

            if (myClass.getName().length()>=5||myClass.getName().trim().length()==0)
            {
                Toast.makeText(Main2Activity.this, myClass.getName()+"不符合命名规则，请重新命名", Toast.LENGTH_LONG).show();

                textView.setText("");
            }
            else
            {
                textView.setText(myClass.getName());
            }

            return convertView;
        }
    }

    class MyClass
    {
        private int img;

        private String name;


        public int getImg() {
            return img;
        }

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

        public String getName() {
            return name;
        }

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

        public MyClass(int img,String name)
        {
            this.img=img;
            this.name=name;
        }
    }
}

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.wang.myapplication.Main2Activity">
    <GridView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/gv_1"
        android:numColumns="4"
        android:gravity="center"
        android:horizontalSpacing="20dp">
    </GridView>

</RelativeLayout>

<?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">
    <ImageView
        android:layout_width="70dp"
        android:layout_height="70dp"
        android:id="@+id/iv_1"/>
    <TextView
        android:layout_width="70dp"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:id="@+id/tv_1"/>

</LinearLayout>