In Java, is there a way to write a string literal without having to escape quotes?
Say you have a String literal with a开发者_如何学Go lot of quotation marks inside it. You could escape them all, but it's a pain, and difficult to read.
In some languages, you can just do this:
foo = '"Hello, World"';
In Java, however, '' is used for chars, so you can't use it for Strings this way. Some languages have syntax to work around this. For example, in python, you can do this:
"""A pretty "convenient" string"""
Does Java have anything similar?
No, and I've always been annoyed by the lack of different string-literal syntaxes in Java.
Here's a trick I've used from time to time:
String myString = "using `backticks` instead of quotes".replace('`', '"');
I mainly only do something like that for a static field. Since it's static the string-replace code gets called once, upon initialization of the class. So the runtime performance penalty is practically nonexistent, and it makes the code considerably more legible.
The answer is no, and the proof resides in the Java Language Specification:
StringLiteral:
"StringCharacters"
StringCharacters:
StringCharacter
| StringCharacters StringCharacter
StringCharacter:
InputCharacter but not " or \
| EscapeSequence
As you can see a StringLiteral can just be bound by " and cannot contain special character without escapes..
A side note: you can embed Groovy inside your project, this will extend the syntax of Java allowing you to use '''multi line string ''', ' "string with single quotes" ' and also "string with ${variable}".
Update Dec. 2018 (12 months later):
Raw string literals (which are on the amber list) won't make it to JDK 12.
See the criticisms here.
There might be in a future version of Java (10 or more).
See JEPS 8196004 from January 2018: ("JEP" is the "JDK Enhancement Program")
JEP draft: Raw String Literals
Add a new kind of literal, a raw string literal, to the Java programming language.
Like the traditional string literal, a raw string literal produces a String, but does not interpret string escapes and can span multiple lines of source code.
So instead of:
Runtime.getRuntime().exec("\"C:\\Program Files\\foo\" bar");
String html = "<html>\n"
" <body>\n" +
" <p>Hello World.</p>\n" +
" </body>\n" +
"</html>\n";
System.out.println("this".matches("\\w\\w\\w\\w"));
You would be able to type:
Runtime.getRuntime().exec(`"C:\Program Files\foo" bar"`);
String html = `<html>
<body>
<p>Hello World.</p>
</body>
</html>
`;
System.out.println("this".matches(`\w\w\w\w`));
Neat!
But it is still just a draft: it will need to posted, submitted, be a candidate, and funded, before being completed and making it into the next JDK.
Since Java 15¹ there is new feature called Text Blocks. It looks similar to what you mentioned is available in Python:
String text = """
{
"property": "value",
"otherProperty": 12
}
""";
More details with examples can be found here: https://openjdk.java.net/jeps/378.
¹ Previewed in Java 13 and 14.
Simple answer: No.
For longer strings that must be escaped, I usually read them from some external resource.
you can also use StringEscapeUtils from apache commons
UPDATE: If someone is interested in some examples here is a useful link : https://dzone.com/articles/commons-lang-3-improved-and-powerful-StringEscapeUtils
You could use left and/or right quotes if you don't mind the difference, they look pretty similar:
"These “double quotes” don't need nor want to be escaped"
The following seems to work for me:
String x = "Some Text" + '"' + "More Text" + '"' + "Even More Text";
I think because char is the primitive variable type for String, Strings and chars can be combined (at least the eclipse compiler doesn't seem to complain).
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