Java示例中的模式asPredicate()方法
java.util.function包的Predicate接口可用作lambda表达式的目标。此接口的测试方法接受一个值，并用谓词对象的当前值对其进行验证。如果有匹配项，则此方法返回true，否则返回false。
java.util.regex.Pattern类的asPredicate()方法返回一个Predicate对象，该对象可以将字符串与正则表达式匹配，使用该正则表达式可以编译当前的Pattern对象。
例子1
import java.util.Scanner;
import java.util.function.Predicate;
import java.util.regex.Pattern;
public class AsPredicateExample {
public static void main( String args[] ) {
//Reading string value
Scanner sc = new Scanner(System.in);
System.out.println("Enter input string");
String input = sc.nextLine();
//Regular expression to find digits
String regex = "[t]";
//Compiling the regular expression
Pattern pattern = Pattern.compile(regex, Pattern.CASE_INSENSITIVE);
//Converting the regular expression to predicate
Predicate<String> predicate = pattern.asPredicate();
//Testing the predicate with the input string
boolean result = predicate.test(input);
if(result) {
System.out.println("Match found");
} else {
System.out.print("Match not found");
}
}
}输出结果
Enter input string Nhooo Number of matches: 3
例子2
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Scanner;
import java.util.function.Predicate;
import java.util.regex.Pattern;
public class AsPredicateExample {
public static void main( String args[] ) {
ArrayList<String> list = new ArrayList<String>();
list.addAll(Arrays.asList("Java", "JavaFX", "Hbase", "JavaScript"));
//Regular expression to find digits
String regex = "[J]";
//Compiling the regular expression
Pattern pattern = Pattern.compile(regex);
//Converting the regular expression to predicate
Predicate<String> predicate = pattern.asPredicate();
list.forEach(n -> { if (predicate.test(n)) System.out.println("Match found "+n); });
}
}输出结果
Match found Java Match found JavaFX Match found JavaScript