【JDK 8-集合框架】5.4 allMatch 和 anyMatch 函数

一、allMatch 函数

二、anyMatch 函数

三、其它函数学习

四、实战

> 执行结果

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一、allMatch 函数

• 检查是否 匹配所有元素，返回 true

二、anyMatch 函数

• 检查是否 至少匹配一个元素，返回 true

三、其它函数学习

• 看源码 + 入参，返回值 学习

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• 如 noneMatch

    /**
     * Returns whether no elements of this stream match the provided predicate.
     * May not evaluate the predicate on all elements if not necessary for
     * determining the result.  If the stream is empty then {@code true} is
     * returned and the predicate is not evaluated.
     *
     * <p>This is a <a href="package-summary.html#StreamOps">short-circuiting
     * terminal operation</a>.
     *
     * @apiNote
     * This method evaluates the <em>universal quantification</em> of the
     * negated predicate over the elements of the stream (for all x ~P(x)).  If
     * the stream is empty, the quantification is said to be vacuously satisfied
     * and is always {@code true}, regardless of P(x).
     *
     * @param predicate a <a href="package-summary.html#NonInterference">non-interfering</a>,
     *                  <a href="package-summary.html#Statelessness">stateless</a>
     *                  predicate to apply to elements of this stream
     * @return {@code true} if either no elements of the stream match the
     * provided predicate or the stream is empty, otherwise {@code false}
     */
    boolean noneMatch(Predicate<? super T> predicate);

四、实战

import java.util.Arrays;
import java.util.List;

public class MatchDemo {
    public static void main(String[] args) {
        List<String> list = Arrays.asList("Spring Boot", "Python", "微服务", "高并发", "Redis", "MongoDB");
        boolean result = list.stream()
                .allMatch(obj -> obj.length() > 7);
        System.out.println(">> allMatch() ：全匹配长度大于7");
        System.out.println(result + "\n");

        result = list.stream()
                .anyMatch(obj -> obj.length() > 1);
        System.out.println(">> anyMatch() ：部分匹配长度大于7");
        System.out.println(result + "\n");

        result = list.stream()
                .noneMatch(obj -> obj.length() > 20);
        System.out.println(">> noneMatch() ：没有一个匹配长度大于20");
        System.out.println(result + "\n");
    }
}

> 执行结果