Java String concat() Method
String concatenation is the process of combining two or more small String to create a bigger String. In Java you can combine string in multiple ways. Using + operator is the easiest way of joining multiple String. Also you can use String.concat() method to joining two strings in Java. But to improve performance, instead of using + operator or String.concat(), use StringBuffer is better choice. All method of concatenating string is following:Using + operator
You can concatenate Strings in Java using the + operator.
String str = "Java " + "String " + "Tutorial";
Above code will return "Java String Tutorial"
Example
class TestClass{
public static void main (String[] args){
String str = "Java " + "String " + "Tutorial";
System.out.println(str);
String str1 = "Java ";
String str2 = "String ";
String str3 = "Tutorial";
String result = str1 + str2 + str3;
System.out.println(result);
}
}
Output
Java String Tutorial
Java String Tutorial
Using StringBuffer
In order to improve performance StringBuffer is the better choice.The quickest way of concatenate two string using + operator.
String str = "Java";
str = str + "Tutorial";
The compiler translates this code as:
String longStr = "Java";
StringBuffer tmpSb = new StringBuffer(longStr);
tmpSb.append("Tutorial");
longStr = tmpSb.toString();
Main reason of performance drop is creation of lots of temporary String object due to immutability of String. Just remember that String concatenation using + operator is also converted to corresponding StringBuffer or StringBuilder call depending upon which version of Java you are using, because StringBuilder is only available from Java 1.5 . So the best approach is to use StringBuffer.
String str = new StringBuffer().append("first").append("second").append("third").toString();
Where possible, it is recommended that this class be used in preference to StringBuffer as it will be faster under most implementations.
Example
class TestClass{
public static void main (String[] args){
String first = "Java ";
String second = "String ";
String third = "Tutorial";
StringBuffer str = new StringBuffer();
str.append(first);
str.append(second);
str.append(third);
System.out.println(str);
}
}
Using Java String concat() method
Java String Concat(String str) method concatenates the specified String to the end of this string.
Example
class TestClass{
public static void main (String[] args){
String first = "Java ";
String second = "Tutorial ";
String str = first.concat(second);
System.out.println(str);
}
}
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