String Concatenation in Java

In java, string concatenation forms a new string that is the combination of multiple strings. There are two ways to concat string in java:

By + (string concatenation) operator
By concat() method

Using + (string concatenation) operator

Java string concatenation operator (+) is used to add strings. For Example:

Example #1

snippet

class TestStringConcatenation1{
 public static void main(String args[]){
   String s="Sachin"+" Tendulkar";
   System.out.println(s);//Sachin Tendulkar
 }
}

Output

Output:Sachin Tendulkar

The Java compiler transforms above code to this:

String s=(new StringBuilder()).append("Sachin").append(" Tendulkar).toString();

In java, String concatenation is implemented through the StringBuilder (or StringBuffer) class and its append method. String concatenation operator produces a new string by appending the second operand onto the end of the first operand. The string concatenation operator can concat not only string but primitive values also. For Example:

Example #2

snippet

class TestStringConcatenation2{
 public static void main(String args[]){
   String s=50+30+"Sachin"+40+40;
   System.out.println(s);//80Sachin4040
 }
}

Output

80Sachin4040

Note

After a string literal, all the + will be treated as string concatenation operator.

Using concat() method

The String concat() method concatenates the specified string to the end of current string. Syntax:

Syntax

public String concat(String another)

Let's see the example of String concat() method.

Example

snippet

class TestStringConcatenation3{
 public static void main(String args[]){
   String s1="Sachin ";
   String s2="Tendulkar";
   String s3=s1.concat(s2);
   System.out.println(s3);//Sachin Tendulkar
  }
}

Output

Sachin Tendulkar