Java add string
last modified July 10, 2024
In this article we show how to concatenate strings in Java.
In Java, a string is a sequence of Unicode characters. Strings are objects. There are two basic classes for working with strings:
There are several ways how to add strings in Java:
- + operator
- concat method
- String.join method
- StringBuilder append method
- String.format
Using the + operator
The easiest way of concatenating strings is to use the + or the
+= operator. The + operator is used both for adding numbers and
strings; in programming we say that the operator is overloaded.
void main() {
System.out.println("Return" + " of " + "the king.");
String msg = "There are";
msg += " three";
msg += " falcons";
msg += " in the sky";
System.out.println(msg);
}
The example adds two strings using the + and +=
operators.
$ java Main.java Return of the king. There are three falcons in the sky
Java add strings with String.concat
The String.concat method concatenates the specified string to the
end of this string.
void main() {
System.out.println("Return".concat(" of ").concat("the king."));
}
In the example, we add strings with String.concat.
Using String.join
The String.join method returns a new atring composed of copies of
the CharSequence elements joined together with a copy of the specified
delimiter.
void main() {
String[] words = { "There", "are", "two", "owls", "on", "the", "tree" };
String msg = String.join(" ", words);
System.out.println(msg);
}
We have an array of words. We form a sentence from the words with the
String.join method.
$ java Main.java There are two owls on the tree
Using StringBuilder
StringBuilder is a mutable sequence of characters. Its append method appends the specified string to the string instance.
void main() {
var sb = new StringBuilder();
sb.append("Return");
sb.append(" of ");
sb.append("the king.");
System.out.println(sb);
}
In the example, we form a new string with StringBuilder.
$ java Main.java Return of the king.
Using String.format
The String.format method returns a formatted string using the
specified format string and arguments.
void main() {
var w1 = "three";
var w2 = "owls";
var msg = String.format("There are %s %s on the tree", w1, w2);
System.out.println(msg);
}
In the example, we build a new string with String.format.
Source
Java String - language reference
In this article we have showed how to add strings in Java.
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