public interface CopyFileListener
    {
        void PublishProgress(long fileSize,long copiedSize);
    }

 textView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                
            }
        });

public class MemoryWare {

    public interface CopyFileListener
    {
        void PublishProgress(long fileSize,long copiedSize);
    }
....
}

SetOnClickListener

 editText.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {

            }

            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {

            }

            @Override
            public void afterTextChanged(Editable s) {

            }
        });

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

        ViewHolder viewHolder=null;
        if(rowView==null)
        {
            // 1. Create inflater
            LayoutInflater inflater = (LayoutInflater) context
                    .getSystemService(Context.LAYOUT_INFLATER_SERVICE);

            // 2. Get rowView from inflater
            rowView = inflater.inflate(R.layout.row_bank_group_list, parent, false);
            viewHolder=new ViewHolder();
            viewHolder.txtGroupName=(TextView) rowView.findViewById(R.id.text_groupName);
            rowView.setTag(viewHolder);
        }
        else
        {
            viewHolder=(ViewHolder)rowView.getTag();
        }
        viewHolder.txtGroupName.setText(getItem(position).getName());
        viewHolder.txtGroupName.setTypeface(new FontSystem().get_General_Font(context));
        viewHolder.txtGroupName.setTextColor(context.getResources().getColor(R.color.black));

        return rowView;
    }

File file=new File(sdcardPath,fileName);

if(file.CanWrite())
{
  .....
}

File file=new File(sdcardPath);

if(file.CanWrite())
{
file=new File(sdcardPath,filePath);
  .....
}

Environment.getExternalStorageDirectory()

/Data/Data

/Data/Data/Info.Dotnettips.MyApp

    /**
     * it will returns sd path for you
     *  <p>
     *  <b>Required Permission: </b>android.permission.READ_EXTERNAL_STORAGE<br/>
     * </p>
     * @return
     */
    public  List<String> GetExternalMounts() {
        final List<String> out = new ArrayList<>();
        String reg = "(?i).*vold.*(vfat|ntfs|exfat|fat32|ext3|ext4).*rw.*";
        String s = "";
        try {
            final Process process = new ProcessBuilder().command("mount")
                    .redirectErrorStream(true).start();
            process.waitFor();
            final InputStream is = process.getInputStream();
            final byte[] buffer = new byte[1024];
            while (is.read(buffer) != -1) {
                s = s + new String(buffer);
            }
            is.close();
        } catch (final Exception e) {
            e.printStackTrace();
        }

        // parse output
        final String[] lines = s.split("\n");
        for (String line : lines) {
            if (!line.toLowerCase(Locale.US).contains("asec")) {
                if (line.matches(reg)) {
                    String[] parts = line.split(" ");
                    for (String part : parts) {
                        if (part.startsWith("/"))
                            if (!part.toLowerCase(Locale.US).contains("vold"))
                                if(new File(part).canWrite())
                                    out.add(part);
                    }
                }
            }
        }
        return out;
    }

notesIntent.putExtra("PartyId", PartyId);
startActivity(notesIntent);

PartyId=getIntent().getLongExtra("PartyId",0);

i.putExtra(FilePickerActivity.EXTRA_ALLOW_MULTIPLE, false);
i.putExtra(FilePickerActivity.EXTRA_ALLOW_CREATE_DIR, false);
i.putExtra(FilePickerActivity.EXTRA_MODE, FilePickerActivity.MODE_FILE);

• برای ثابت‌ها از حروف بزرگ و _ استفاده کنید.
• برای متغیرهای خصوصی از حرف m در ابتدای نام متغیر استفاده کنید.
• برای متغیرهای استاتیک از حرف s در ابتدای نام متغیر استفاده کنید.

public class MyClass {
    public static final int SOME_CONSTANT = 42;
    public int publicField;
    private static MyClass sSingleton;
    int mPackagePrivate;
    private int mPrivate;
    protected int mProtected;
}

1. نام پکیج‌های ارائه شده توسط گوگل
2. نام پکیج‌های ثالث
3. نام پکیج‌های موجود در java و javax
4. پکیج‌های موجود در پکیج اصلی
   

public, protected, private,abstract, static, transient, volatile, synchronized, final, native.

Settings>Editor>Code Style>Arrangement

Settings>Editor>Completion>Case-sensitive Completion>None

    public class Bill
    {
        public int Id { set; get; }
        public string Name { set; get; }

        public virtual ICollection<Transaction> Transactions { set; get; }
    }

    public class Transaction
    {
        public int Id { set; get; }
        public DateTime AddDate { set; get; }
        public int Amount { set; get; }

        [ForeignKey("BillId")]
        public virtual Bill Bill { set; get; }
        public int BillId { set; get; }
    }

    public class MyContext : DbContext
    {
        public DbSet<Bill> Bills { get; set; }
        public DbSet<Transaction> Transactions { get; set; }
    }

    public class Configuration : DbMigrationsConfiguration<MyContext>
    {
        public Configuration()
        {
            AutomaticMigrationsEnabled = true;
            AutomaticMigrationDataLossAllowed = true;
        }

        protected override void Seed(MyContext context)
        {
            var bill1 = new Bill { Name = "bill-1" };
            context.Bills.Add(bill1);

            for (int i = 0; i < 11; i++)
            {
                context.Transactions.Add(new Transaction
                {
                    AddDate = DateTime.Now.AddDays(-i),
                    Amount = 1000000000 + i,
                    Bill = bill1
                });
            }
            base.Seed(context);
        }
    }

    public static class Test
    {
        public static void RunTests()
        {
            Database.SetInitializer(new MigrateDatabaseToLatestVersion<MyContext, Configuration>());
            using (var context = new MyContext())
            {
                var sum = context.Transactions.Sum(x => x.Amount);
                Console.WriteLine(sum);
            }
        }
    }

SELECT 
         [GroupBy1].[A1] AS [C1]
         FROM ( SELECT 
                    SUM([Extent1].[Amount]) AS [A1]
                    FROM [dbo].[Transactions] AS [Extent1]
                    )  AS [GroupBy1]

 Arithmetic overflow error converting expression to data type int.

var sum2 = context.Transactions.Sum(x => (Int64)x.Amount);

SELECT 
      [GroupBy1].[A1] AS [C1]
         FROM ( SELECT 
                    SUM( CAST( [Extent1].[Amount] AS bigint)) AS [A1]
                    FROM [dbo].[Transactions] AS [Extent1]
               )  AS [GroupBy1]                  

var date = DateTime.Now.AddDays(10);
var sum3 = context.Transactions
                  .Where(x => x.AddDate > date)  
                  .Sum(x => (Int64)x.Amount);               

SELECT 
     [GroupBy1].[A1] AS [C1]
        FROM ( SELECT 
                    SUM( CAST( [Extent1].[Amount] AS bigint)) AS [A1]
                    FROM [dbo].[Transactions] AS [Extent1]
                    WHERE [Extent1].[AddDate] > @p__linq__0
              )  AS [GroupBy1]

The cast to value type 'Int64' failed because the materialized value is null.
Either the result type's generic parameter or the query must use a nullable type.

var date = DateTime.Now.AddDays(10);
var sum3 = context.Transactions
                  .Where(x => x.AddDate > date)
                  .Sum(x => (Int64?)x.Amount) ?? 0;

 var sum4 = context.Bills.First().Transactions.Sum(x => (Int64?)x.Amount) ?? 0;

SELECT 
     [Extent1].[Id] AS [Id], 
     [Extent1].[AddDate] AS [AddDate], 
     [Extent1].[Amount] AS [Amount], 
     [Extent1].[BillId] AS [BillId]
   FROM [dbo].[Transactions] AS [Extent1]
   WHERE [Extent1].[BillId] = @EntityKeyValue1

var entry = context.Bills.First();
var sum5 = context.Entry(entry).Collection(x => x.Transactions).Query().Sum(x => (Int64?)x.Amount) ?? 0;

SELECT 
    [GroupBy1].[A1] AS [C1]
     FROM ( SELECT 
               SUM( CAST( [Extent1].[Amount] AS bigint)) AS [A1]
                   FROM [dbo].[Transactions] AS [Extent1]
                    WHERE [Extent1].[BillId] = @EntityKeyValue1
            )  AS [GroupBy1]                  

 public class SendEmailsTask : ScheduledTaskTemplate

using System;

namespace DNTScheduler.TestWebApplication.WebTasks
{
    public class SendEmailsTask : ScheduledTaskTemplate
    {
        /// <summary>
        /// اگر چند جاب در یک زمان مشخص داشتید، این خاصیت ترتیب اجرای آن‌ها را مشخص خواهد کرد
        /// </summary>
        public override int Order
        {
            get { return 1; }
        }

        public override bool RunAt(DateTime utcNow)
        {
            if (this.IsShuttingDown || this.Pause)
                return false;

            var now = utcNow.AddHours(3.5);
            return now.Minute % 2 == 0 && now.Second == 1;
        }

        public override void Run()
        {
            if (this.IsShuttingDown || this.Pause)
                return;

            System.Diagnostics.Trace.WriteLine("Running Send Emails");
        }

        public override string Name
        {
            get { return "ارسال ایمیل"; }
        }
    }
}

        public override bool RunAt(DateTime utcNow)
        {
            if (this.IsShuttingDown || this.Pause)
                return false;

            var now = utcNow.AddHours(3.5);
            return now.Hour == 23 && now.Minute == 33 && now.Second == 1;
        }

using System;
using System.Net;

namespace DNTScheduler.TestWebApplication.WebTasks
{
    public static class ScheduledTasksRegistry
    {
        public static void Init()
        {
            ScheduledTasksCoordinator.Current.AddScheduledTasks(
                new SendEmailsTask(),
                new DoBackupTask());

            ScheduledTasksCoordinator.Current.OnUnexpectedException = (exception, scheduledTask) =>
            {
                //todo: log the exception.
                System.Diagnostics.Trace.WriteLine(scheduledTask.Name + ":" + exception.Message);
            };

            ScheduledTasksCoordinator.Current.Start();
        }

        public static void End()
        {
            ScheduledTasksCoordinator.Current.Dispose();
        }

        public static void WakeUp(string pageUrl)
        {
            try
            {
                using (var client = new WebClient())
                {
                    client.Credentials = CredentialCache.DefaultNetworkCredentials;
                    client.Headers.Add("User-Agent", "ScheduledTasks 1.0");
                    client.DownloadData(pageUrl);
                }
            }
            catch (Exception ex)
            {
                //todo: log ex
                System.Diagnostics.Trace.WriteLine(ex.Message);
            }
        }
    }
}

using System;
using System.Configuration;
using DNTScheduler.TestWebApplication.WebTasks;

namespace DNTScheduler.TestWebApplication
{
    public class Global : System.Web.HttpApplication
    {
        protected void Application_Start(object sender, EventArgs e)
        {
            ScheduledTasksRegistry.Init();
        }

        protected void Application_End()
        {
            ScheduledTasksRegistry.End();
            //نکته مهم این روش نیاز به سرویس پینگ سایت برای زنده نگه داشتن آن است
            ScheduledTasksRegistry.WakeUp(ConfigurationManager.AppSettings["SiteRootUrl"]);
        }
    }
}

 <?xml version="1.0"?>
<configuration>
  <appSettings>
      <add key="SiteRootUrl" value="http://localhost:10189/Default.aspx" />
  </appSettings>
</configuration>

var jobsList = ScheduledTasksCoordinator.Current.ScheduledTasks.Select(x => new
{
   TaskName = x.Name,
   LastRunTime = x.LastRun,
   LastRunWasSuccessful = x.IsLastRunSuccessful,
   IsPaused = x.Pause,
}).ToList();

public interface IUnitOfWork
    {
        ISession CurrentSession { get; }
        void BeginTransaction();
        void Commit();
        void RollBack();
    }

[Export(typeof(IUnitOfWork)]
    public class UnitOfWork : IUnitOfWork
    {
        public ISession CurrentSession
        {
            get { throw new NotImplementedException(); }
        }

        public void BeginTransaction()
        {
            throw new NotImplementedException();
        }

        public void Commit()
        {
            throw new NotImplementedException();
        }

        public void RollBack()
        {
            throw new NotImplementedException();
        }
    }

 public class Respository
    {

       [Import]

       private IUnitOfWork uow;

        public Respository()
        {
        }    
    }

public class Person 
{ 
    public string _firstName; 
 
    public string FirstName 
    { 
        get 
        { 
            return _firstName; 
        } 
        set 
        { 
            _firstName = value; 
        } 
    }  
}

public string _firstName; 
public string FirstName 
{ 
    get 
    { 
        return _firstName; 
    } 
    private set 
    { 
        _firstName = value; 
    } 
}

public class Person
{
   public string FirstName { get; set; }
}

public class User
{
   public string Name { get; private set; }
}

public class User
{
   public string Name { get; }
}

public class Foo
{
   public string FirstName { get; set; } = "Initial Value";
}

public class Foo
{  
   public DateTime DateOfBirth { get; set; }
   public int Age => DateTime.Now.Year - DateOfBirth.Year;  
}

public class User
{
   public string Name { get; private set; }
}

var user = new User
{
   Name = "User 1" // Compile Error
};

The property or indexer 'User.Name' cannot be used in this context
because the set accessor is inaccessible [CS9Features]csharp(CS0272)

public class User
{
  public User(string name)
  {
    this.Name = name;
  }

  public void SetName(string name)
  {
    this.Name = name;
  }

  public string Name { get; private set; }
}

public class User
{
   public string Name { get; init; }
}

var user = new User
{
   Name = "User 1"
};

// Compile Time Error
// Init-only property or indexer 'User.Name' can only be assigned in an object initializer,
// or on 'this' or 'base' in an instance constructor or an 'init' accessor. [CS9Features]csharp(CS8852)
user.Name = "Test";

public class User
{
   public string Name { get; init; }

   public User(string name)
   {
     this.Name = name; // Works fine
   }

   public void SetName(string name)
   {
     this.Name = name; // Compile Time Error
   }
}

    public class Product
    {
        public Product(string name)
        {
            _name = name;
        }

        private readonly string _name;

        public string Name => _name;
    }

    public class Person
    {
        private readonly string _name;

        public string Name
        {
            get => _name;
            init => _name = value;
        }
    }

public class Program
{
    public static void Main(string[] args)
    {
        var host = new WebHostBuilder()
            .UseKestrel()
            .UseContentRoot(Directory.GetCurrentDirectory())
            .UseIISIntegration()
            .UseStartup<Startup>()
            .Build();
 
        host.Run();
    }
}

 "dependencies": {
   // same as before
    "Microsoft.AspNetCore.StaticFiles": "1.0.0"
},

public class Startup
{
    public void ConfigureServices(IServiceCollection services)
    {
    }
 
    public void Configure(IApplicationBuilder app)
    {
        app.UseStaticFiles();
        //app.UseWelcomePage();
 
        app.Run(async context =>
        {
            await context.Response.WriteAsync("Hello DNT!");
        });
    }
}

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8" />
    <title>Hello World</title>
</head>
<body>
    Hello World!
</body>
</html>

public void Configure(IApplicationBuilder app)
{
   app.UseDefaultFiles();
   app.UseStaticFiles();

 // Serve my app-specific default file, if present.
DefaultFilesOptions options = new DefaultFilesOptions();
options.DefaultFileNames.Clear();
options.DefaultFileNames.Add("mydefault.html");
app.UseDefaultFiles(options);

public void Configure(IApplicationBuilder app)
{
  app.UseStaticFiles();
  app.UseDefaultFiles();

○ wwwroot
   § css
   § images
   § ...
○ MyStaticFiles
   § test.png

app.UseStaticFiles(new StaticFileOptions
{
    FileProvider = new PhysicalFileProvider(root: Path.Combine(Directory.GetCurrentDirectory(), @"MyStaticFiles")),
    RequestPath = new PathString("/StaticFiles")
});

app.UseDirectoryBrowser(new DirectoryBrowserOptions
{
    FileProvider = new PhysicalFileProvider(root: Path.Combine(Directory.GetCurrentDirectory(), @"wwwroot\images")),
    RequestPath = new PathString("/MyImages")
});

 Unable to resolve service for type 'System.Text.Encodings.Web.HtmlEncoder' while attempting to activate 'Microsoft.AspNetCore.StaticFiles.DirectoryBrowserMiddleware'.

public void ConfigureServices(IServiceCollection services)
{
   services.AddDirectoryBrowser();
}

app.UseStaticFiles(new StaticFileOptions
{
    FileProvider = new PhysicalFileProvider(root: Path.Combine(Directory.GetCurrentDirectory(), @"wwwroot\images")),
    RequestPath = new PathString("/MyImages")
});

using System.IO;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.FileProviders;
 
namespace Core1RtmEmptyTest
{
    public class Startup
    {
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddDirectoryBrowser();
        }
 
        public void Configure(IApplicationBuilder app)
        {
            app.UseDefaultFiles();
 
            app.UseStaticFiles(); // For the wwwroot folder
 
            // For the files outside of the wwwroot
            app.UseStaticFiles(new StaticFileOptions
            {
                FileProvider = new PhysicalFileProvider(root: Path.Combine(Directory.GetCurrentDirectory(), @"MyStaticFiles")),
                RequestPath = new PathString("/StaticFiles")
            });
 
            // For DirectoryBrowser
            app.UseStaticFiles(new StaticFileOptions
            {
                FileProvider = new PhysicalFileProvider(root: Path.Combine(Directory.GetCurrentDirectory(), @"wwwroot\images")),
                RequestPath = new PathString("/MyImages")
            });
 
            app.UseDirectoryBrowser(new DirectoryBrowserOptions
            {
                FileProvider = new PhysicalFileProvider(root: Path.Combine(Directory.GetCurrentDirectory(), @"wwwroot\images")),
                RequestPath = new PathString("/MyImages")
            });
 
            //app.UseWelcomePage();
 
            app.Run(async context =>
            {
                await context.Response.WriteAsync("Hello DNT!");
            });
        }
    }
}

 app.UseFileServer();

 app.UseFileServer(enableDirectoryBrowsing: true);

app.UseFileServer(new FileServerOptions
    {
        FileProvider = new PhysicalFileProvider(
            Path.Combine(Directory.GetCurrentDirectory(), @"MyStaticFiles")),
        RequestPath = new PathString("/StaticFiles"),
        EnableDirectoryBrowsing = false
    });

 // Set up custom content types -associating file extension to MIME type
var provider = new FileExtensionContentTypeProvider();
provider.Mappings[".xyz"] = "text/html";
 
app.UseStaticFiles(new StaticFileOptions
{
    ContentTypeProvider = provider
}) ; // For the wwwroot folder

public class XyzContentTypeProvider : FileExtensionContentTypeProvider
{
    public XyzContentTypeProvider()
    {
        this.Mappings.Add(".xyz", "text/html");
    }
}

app.UseStaticFiles(new StaticFileOptions
{
    ContentTypeProvider = new XyzContentTypeProvider()
}) ; // For the wwwroot folder

app.UseStaticFiles(new StaticFileOptions
{
    ServeUnknownFileTypes = true,
    DefaultContentType = "image/png"
});

public enum CustomerType 
{ 
     Person = 0, 
     Company = 1 
} 
public class Customer 
{ 
    public CustomerType Type { get; set; } 
}

با وجود چنین کلاسی از مشتری و نیاز به انجام فعالیت‌های مختلفی بر روی آن، احتمالا نیاز خواهد بود که در بخش‌های مختلف کد، گذاره‌ی switch ای مانند زیر را اضافه کنید:  

switch (customer.Type) 
{ 
      case CustomerType.Person: 
         // calculate discount, or send message or edit customer or anything else 
          break; 
      case CustomerType.Company: 
          // calculate discount, or send message or edit customer or anything else 
          break; 
      default: 
          throw new ArgumentOutOfRangeException(); 
 }

برای انجام فعالیت‌های مختلفی مانند محاسبه تخفیف، ارسال پیام و یا ویرایش مشتری، نیاز خواهد بود این گذاره تکرار شود که خود این موضوع بوی بد duplicate code است و به الگوی shotgun surgery نیز ختم خواهد شد. 

حال فرض کنید نیاز است مشتریان حقوقی، خود به دو نوع مشتری حقوقی بخش خصوصی و مشتری حقوقی بخش دولتی تقسیم شوند. در پیاده سازی ذکر شده باید به CustomerType یک آیتم افزوده شود و در تمامی switch‌ها نیز در صورت نیاز شرط مربوط به آن اضافه شود.  

برای حل این نوع از کد بد بو، معمولا یک کلاس پدر را به نام مشتری ایجاد کرده و کلاس‌های مختص هر یک از انواع مشتری را از آن به ارث می‌برند (Replace type code with subclass):

یا می‌توان طراحی را کمی متفاوت‌تر و به صورت زیر انجام داد:

دلیل مشابه دیگر ایجاد این الگوی بد کد استفاده از type code به عنوان وضعیت یک تایپ است. که در این صورت می‌توان بجای type code از state object استفاده کرد (Replace type code with strategy). به این مورد در مباحث مربوط به refactoring به طور مفصل پرداخته شده است.

جمع بندی 

این کد بد بو در شرایط متفاوتی ایجاد می‌شود. با این حال یکی از پر تکرارترین آنها استفاده بد یا عدم استفاده از الگوهای طراحی شیء گرا است. تصحیص این الگوی بد، به خوانایی و نگهداری کد در بلند مدت کمک بسیار زیادی می‌کند.