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Java String concat() usage and example

Java String (String) Methods

The Java String concat() method concatenates (joins) two strings and returns it.

The syntax of the string concat() method is:

str.concat(String str1)

The concat() parameter

  • str1 - The strings to be concatenated

The return value of concat()

  • Returns a string that is the concatenation of str and str1The concatenated string (parameter string)

Example: Java concat()

class Main {}}
　　public static void main(String[] args) {
　　　　String str1　= "Learn";
　　　　String str2　= "Java";
　　　　//concat str1and str2
　　　　System.out.println(str1.concat(str2))　//　"Learn　Java"
　　　　//　concat str2and str11
　　　　System.out.println(str2.concat(str1))　//　"JavaLearn　"
　　}
}

Use + operator for string concatenation

In Java, you can also use + operators to concatenate two strings. For example,

class Main {}}
　　public static void main(String[] args) {
　　　　String str1　= "Learn";
　　　　String str2　= "Java";
　　　　//concat str1and str2
　　　　System.out.println(str1　+　str2);　//　"Learn　Java"
　　　　//concat str2and str11
　　　　System.out.println(str2　+　str1);　//　"JavaLearn　"
　　}
}

concat() with+ operator performs concatenation

concat()+operator

Assume str1is null, str2is "Java".

Then, str1.concat(str2) throwsNullPointerException.

Assumestr1is null,str2is "Java".
Then, str1 + str2Provide"nullJava".

You can only pass a String to the concat() method.

If one of the operands is a string and the other is not a string value.

Before the connection, non-string values will be internally converted to strings.

For example, "Java" + 5Provide "Java5".

Java String (String) Methods

Java Method OverloadingComprehensive Java String Methods