Java Equivalent of C# Language features

I’ve been playing around with C# for more than 2 years. Recently got a chance to explore Java.

I didn’t have much idea of Java except that both are quite similar in construct. All I needed to find is the equivalents of C# features in Java.

This post covers the Java equivalent of some of the popular C# features, classes, or methods in brief. I’ll add more to this list in the future. If you feel any important feature is missing, feel free to add a comment.

I assume the reader has some basic to medium programming experience.

C# Linq

Java Equivalent for C# Linq is Streams introduced in Java 8.

Where()

C# Example:

List<User> filteredUsers = users.Where(u => u.Name == "Soundar")
                         .ToList();

Java Example:

List<User> filteredUsers = users.stream()
                         .filter(u -> u.Name == "Soundar")
                         .collect(Collectors.toList());

Skip(), Take()

C# Example

List<User> filteredUsers = users.Skip((page - 1) * pageSize)
                         .Take(pageSize)
                         .ToList();

Java Example

List<User> filteredUsers = users.stream()
                               .skip((page - 1) * pageSize)
                               .limit(pageSize)
                              .collect(Collectors.toList());

More examples on streams are here

Collections

List

C# Example

List<User> user = new List<User>();

Java Example

List<User> user = new ArrayList<User>();  // or new ArrayList<>():

More collection examples are here

String.IsNullOrEmpty()

C# Example

bool hasValue = String.IsNullOrEmpty(""); 

Java Example: isBlank() as of JDK11

// isBlank() as of JDK11
bool hasValue = (str == null) || str.isBlank();
// for before JDK11 
bool hasValue = (str == null) || str.length() == 0;

Null Conditional or Optional Chaining Operator

C# Example

string userCountry = user?.Address?.Country;

Java Example

string user Country = (user != null && user.Address != null) ? user.Address.Country : "";

Null Coalescing

C# Example

int? x = null;
//if x is null 0 is assigned else value of x is assigned
int y= x ?? 0;

Java Example

int y = (x != null) ? x : 0;

@ – Verbatim Identifier

C# Example

//multiline text
string multiline = @"select * from users
                    where id = 1";
//escaping
string filePath = @"C:\Program Files\";

Java Example

//multiline
String s = "select * from users \n"
          + "where id = 1";
//escaping
string filePath = "C:\\Program Files\\";

$ – String interpolation

C# Example

int value1 = 1;
string example = $"We can use variables or values inside string { value1 }";

Java Example

String.format("name=%s email=%s", name, email);

Object Initializer

C# Example

User user = new User() { 
                Name = "Soundar", 
                Email = "example@gmail.com"
             };

Java Example: In Java, there is no object initializer feature. We need to use the constructor or classic setter methods

User user = new User();
user.setName("Soundar");
user.setEmail("example@gmail.com");

Getter Setter

C# Example

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

Java Example

class User
{
  private String name;

  public String getName()
  {
    return this.name;
  }

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

Generics

Java generics is quite similar to C#. For detailed example, check here.

C# Example:

//class
public class ExampleClass<T>
{
}
//method
public void Method<T>(T param)
{
}

Java Example:

//class
public class ExampleClass<T>
{
}
//method
public <T> void method(T param)
{
}

Type Conversion

C# Example:

//string to int
Int16.Parse("100");  //throws exception for invalid input
Int64.Parse("2147483649");  //throws exception for invalid input
int.Parse("30,000");  //throws exception for invalid input
Convert.ToInt16("100")  //throws exception for invalid input
Convert.ToInt32("100")  //throws exception for invalid input
Convert.ToInt64("100") //throws exception for invalid input
bool isValidNumber = Int32.TryParse("1000", out number); //no exception

// int to string
int num = 10;
string str = Convert.ToString(num);
string str1 = num.ToString();

Java Example:

//string to int
Integer.parseInt("200"); //throws exception for invalid input
Integer.valueOf("200");  //throws exception for invalid input

//int to string
String.valueOf(200);
Integer.toString(200)

For more on type conversions, refer this

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I hope the above Java equivalents will be handy and help you get started in Java as a C# Developer.

Happy Coding 🙂