Java – String concat() Method

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In this tutorial we will learn how to concatenate multiple strings using concat() method in Java.

Internal implementation

public String concat(String str) 
{  
       int otherLen = str.length();  
       if (otherLen == 0) 
       {  
           return this;  
       }  
       int len = value.length;  
       char buf[] = Arrays.copyOf(value, len + otherLen);  
       str.getChars(buf, len);  
       return new String(buf, true);  
   }
Signature

The signature of string concat() method is given below:


public String concat(String anotherString)
Parameter

anotherString : another string i.e. to be combined at the end of this string.

Returns

combined string

Example

public class Test1 
{
   public static void main(String args[]) 
   {
       //One way of doing concatenation
       String str1 = "Welcome";
       str1 = str1.concat(" to ");
       str1 = str1.concat(" String handling ");
       System.out.println(str1);

       //Other way of doing concatenation in one line
       String str2 = "This";
       str2 = str2.concat(" is").concat(" just a").concat(" String");
       System.out.println(str2);
   }
}


Output:

Welcome to  String handling 
This is just a String
Java String concat() method example

public class Text
{  
public static void main(String args[])
{  
String s1="java string";  
s1.concat("is immutable");  
System.out.println(s1);  
s1=s1.concat(" is immutable so assign it explicitly");  
System.out.println(s1);  
}
}


Output:

java string
java string is immutable so assign it explicitly
Java String concat() Method Example

See an example where we are concatenating multiple string objects.


public class Test 
{  
    public static void main(String[] args) 
    {      
        String str1 = "Hello";  
        String str2 = "Rama";  
        String str3 = "krishna";  
        // Concatenating one string   
        String str4 = str1.concat(str2);          
        System.out.println(str4);  
        // Concatenating multiple strings  
        String str5 = str1.concat(str2).concat(str3);  
        System.out.println(str5);  
    }  
}


Output:

HelloRama
HelloRamakrishna
Java String concat() Method Example

public class Test1
{  
    public static void main(String[] args) 
   {  
        String str1 = "Hello";  
        String str2 = "Rama";  
        String str3 = "krishna";  
        // Concatenating Space among strings  
        String str4 = str1.concat(" ").concat(str2).concat(" ").concat(str3);  
        System.out.println(str4);         
        // Concatenating Special Chars        
        String str5 = str1.concat("!!!");  
        System.out.println(str5);         
        String str6 = str1.concat("@").concat(str2);  
        System.out.println(str6);  
    }  
}


Output:

Hello Rama krishna
Hello!!!
Hello@Rama



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