import java.io.File;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.format.DateTimeFormatter;
import static java.lang.StringTemplate.RAW;
import static java.util.FormatProcessor.FMT;
/**
* Examples taken from JEP 430
*/
public class StringPatternsPreview1 {
public static void main(String[] args) {
// Embedded expressions can be strings
String firstName = "Bill", lastName = "Duck";
System.out.println(STR."\{firstName} \{lastName}");
// Embedded expressions can perform arithmetic
int x = 10, y = 20;
System.out.println(STR."\{x} + \{y} = \{x + y}");
// Embedded expressions can invoke methods and access fields
System.out.println(STR."You have a \{getOfferType()} waiting for you!");
Request req = new Request();
System.out.println(STR."Access at \{req.date} \{req.time} from \{req.ipAddress}");
// Embedded expressions can use double quotes without escaping them
String filePath = "_dummy.dat";
File file = new File(filePath);
System.out.println(STR."The file \{filePath} \{file.exists() ? "does" : "does not"} exist");
// Embedded expressions can span multiple lines
System.out.println(
STR."The time is \{
DateTimeFormatter
.ofPattern("HH:mm:ss")
.format(LocalTime.of(11, 11, 11))
} or roughly eleven after eleven"
);
// Embedded expressions can be nested
String[] fruit = { "apples", "oranges", "peaches" };
System.out.println(STR."\{fruit[0]}, \{STR."\{fruit[1]}, \{fruit[2]}"}\n");
// Embedded expressions can be used in multi-line strings
String title = "My Web Page";
String text = "Hello, world";
String html = STR."""
\{title}
\{text}
""";
System.out.println(html);
// The FMT template processor interprets format specifiers which appear to the left of embedded expressions.
// The format specifiers are the same as those defined in java.util.Formatter.
Rectangle[] zone = new Rectangle[] {
new Rectangle("Alfa", 17.8, 31.4),
new Rectangle("Bravo", 9.6, 12.4),
new Rectangle("Charlie", 7.1, 11.23),
};
String table = FMT."""
Description Width Height Area
%-12s\{zone[0].name} %7.2f\{zone[0].width} %7.2f\{zone[0].height} %7.2f\{zone[0].area()}
%-12s\{zone[1].name} %7.2f\{zone[1].width} %7.2f\{zone[1].height} %7.2f\{zone[1].area()}
%-12s\{zone[2].name} %7.2f\{zone[2].width} %7.2f\{zone[2].height} %7.2f\{zone[2].area()}
\{" ".repeat(28)} Total %7.2f\{zone[0].area() + zone[1].area() + zone[2].area()}
""";
System.out.println(table);
// Built-in security: Each template expression needs to pass through a processor.
String name = "Joan";
StringTemplate stringTemplate = RAW."My name is \{name}";
String processedTemplate = STR.process(stringTemplate);
System.out.println(processedTemplate);
}
static Object getOfferType() {
return "special New Year's sale discount";
}
static class Request {
LocalDate date;
LocalTime time;
InetAddress ipAddress;
Request() {
LocalDateTime dateTime = LocalDateTime.of(2011, 11, 11, 11, 11, 11);
date = dateTime.toLocalDate();
time = dateTime.toLocalTime();
try {
// localhost/127.0.0.1
ipAddress = InetAddress.getByAddress("localhost", new byte[] { 127, 0, 0, 1 });
} catch (UnknownHostException e) {
throw new RuntimeException(e);
}
}
}
record Rectangle(String name, double width, double height) {
double area() {
return width * height;
}
}
}