java8 lambda Predicate示例

import java.util.Arrays;
import java.util.List;
import java.util.function.Predicate;

public class PredicateTest {
    public static void main(String[] args) {
        List<String> languages = Arrays.asList("Java", "Scala", "C++", "Haskell", "Lisp");

        System.out.println("Languages which starts with J :");
        filter(languages, (str) -> String.valueOf(str).startsWith("J"));

        System.out.println("Languages which ends with a ");
        filter(languages, (str) -> String.valueOf(str).endsWith("a"));

        System.out.println("Print all languages :");
        filter(languages, (str)->true);

        System.out.println("Print no language : ");
        filter(languages, (str)->false);

        System.out.println("Print language whose length greater than 4:");
        filter(languages, (str)->String.valueOf(str).length() > 4);


        //过滤双条件
        // 甚至可以用and()、or()和xor()逻辑函数来合并Predicate，
        // 例如要找到所有以J开始，长度为四个字母的名字，你可以合并两个Predicate并传入
        Predicate<String> startsWithJ = (n) -> n.startsWith("J");
        Predicate<String> fourLetterLong = (n) -> n.length() == 4;
        languages.stream()
                .filter(startsWithJ.and(fourLetterLong))
                .forEach((n) -> System.out.print("nName, which starts with 'J' and four letter long is : " + n));

    }

    public static void filter(List<String> names, Predicate condition) {
        for(String name: names)  {
            if(condition.test(name)) {
                System.out.println(name + " ");
            }
        }
    }
}