So, we all should know that you can include variables into strings by doing:
String string = "A string " + aVariable;
Is there a way to do it like:
String string = "A string {aVariable}";
In other words: Without having to close the quotation marks and adding plus signs. It's very unattractive.
You can always use String.format(....). i.e.,
String string = String.format("A String %s %2d", aStringVar, anIntVar);
I'm not sure if that is attractive enough for you, but it can be quite handy. The syntax is the same as for printf and java.util.Formatter. I've used it much especially if I want to show tabular numeric data.
format is more attractive than a simple String concatenation expression. Where format comes into its own is when you need to do padding, number formatting, etcetera.
1 + "oops"), especially if you use FindBugs (which parses format strings and input parameters). And, as the asker says, in many cases it's more readable. Of course, it's a shame that the format method has been made static, that was a rather stupid design mistake.asFormat would make more sense. Of course, the fact that Eclipse does not work that well with static imports makes it a bit more painful to use the current String.format as well.This is called string interpolation; it doesn't exist as such in Java.
One approach is to use String.format:
String string = String.format("A string %s", aVariable);
Another approach is to use a templating library such as Velocity or FreeMarker.
Also consider java.text.MessageFormat, which uses a related syntax having numeric argument indexes. For example,
String aVariable = "of ponies";
String string = MessageFormat.format("A string {0}.", aVariable);
results in string containing the following:
A string of ponies.
More commonly, the class is used for its numeric and temporal formatting. An example of JFreeChart label formatting is described here; the class RCInfo formats a game's status pane.
String.format() method.
Since Java 15, you can use a non-static string method called String::formatted(Object... args)
Example:
String foo = "foo";
String bar = "bar";
String str = "First %s, then %s".formatted(foo, bar);
Output:
"First foo, then bar"
Apache Commons Text's StringSubstitutor can be used. See the library's Dependency Information for how to include it in a project.
import org.apache.commons.text.StringSubstitutor;
// ...
Map<String, String> values = new HashMap<>();
values.put("animal", "quick brown fox");
values.put("target", "lazy dog");
StringSubstitutor sub = new StringSubstitutor(values);
String result = sub.replace("The ${animal} jumped over the ${target}.");
// "The quick brown fox jumped over the lazy dog."
This class supports providing default values for variables.
String result = sub.replace("The number is ${undefined.property:-42}.");
// "The number is 42."
To use recursive variable replacement, call setEnableSubstitutionInVariables(true);.
Map<String, String> values = new HashMap<>();
values.put("b", "c");
values.put("ac", "Test");
StringSubstitutor sub = new StringSubstitutor(values);
sub.setEnableSubstitutionInVariables(true);
String result = sub.replace("${a${b}}");
// "Test"
The library can be found on Maven central repository. This is the Maven dependency:
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-text</artifactId>
<version>1.10.0</version>
</dependency>
you can use String format to include variables within strings
i use this code to include 2 variable in string:
String myString = String.format("this is my string %s %2d", variable1Name, variable2Name);
String.format()is built-in to the language.