Java concatenate strings



In this chapter we will be learning Concatenating two strings in java programming. Concatenating two strings means combining two objects in java.

Joining two Strings [Concatenate Strings] in Java :

Consider the following example –

public class ConcatenateString {
    public static void main(String[] args) {
       String Str1 = "I love";
       String Str2 = "my country";
       String Str3 = "India";

       String myString; 
       myString = Str1 + Str2 + Str3;
       System.out.println("Complete Statement : " + myString);

       myString = Str3 + 10 + 10;
       System.out.println("Complete Statement : " + myString);

       myString = 10 + 10 + Str3;
       System.out.println("Complete Statement : " + myString);
   }
}

Output :

Complete Statement : I love my country India
Complete Statement : India1010
Complete Statement : 20India

Explanation of the Program :

In Java Programming when two strings will be combined together then it will create another object of string. Below are some thumb rules while adding or combining two strings.

Operand 1Operand 2Result of Concatenation
IntegerStringString
StringStringString
IntegerIntegerInteger

  1. ‘+’ operator has associtivity from left to right.
  2. Each time + operator will check the type of operands and then decide which operation to perform.
  3. If any of the operand is of type String then another type will converted to String using respective wrapper classes.

First Concatenation :

myString = Str1 + Str2 + Str3;
         = "I love " + "my country " + "India"
         = "I love my country " + "India"
         = "I love my country India"

Second Concatenation :

myString = Str3 + 10 + 10;
         = "India" + 10 + 10
         = "India10" + 10
         = "India1010"

Third Concatenation :

myString = 10 + 10 + Str3;
         = 10 + 10 + "India"
         = 20 + "India"
         = "20India"