Hoc GridView cơ bản trong android

Code file MainActivity.java

package com.example.macbookpro.dtsondcgridviewtext;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.GridView;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {
    GridView grvDienThoai;
    String arrDt[] = {"Iphone 5","Iphone 5s", "Iphone 6", "Iphone 6s", "Samsung s6", "Samsung s7","Samsung note 4", "Samsung note 5","Htc m9","Htc m10"};
    @Override    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        // anh xa        grvDienThoai = (GridView) findViewById(R.id.gridViewDienThoai);
        final ArrayAdapter<String> adapter = new ArrayAdapter<String>(MainActivity.this,android.R.layout.simple_list_item_1,arrDt);
        grvDienThoai.setAdapter(adapter);

        // thiet lap su kien click tren GridView        grvDienThoai.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                Toast.makeText(MainActivity.this,"Ban dang chon: "+arrDt[position],Toast.LENGTH_LONG).show();
            }
        });
    }
}

Code file xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout 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"    android:orientation="vertical"    tools:context="com.example.macbookpro.dtsondcgridviewtext.MainActivity">

    <GridView        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:numColumns="3"        android:id="@+id/gridViewDienThoai" />
</LinearLayout>