Java Java.util.function.DoublePredicate用法及代码示例

DoublePredicate接口被引入JDK 8。该接口封装在java.util.function包。它对 Double 对象进行操作并根据条件返回谓词值。它是一个函数接口因此可以用于拉姆达表达式还。

public interface DoublePredicate

方法

test()：此函数对双精度值进行条件检查，并返回一个表示结果的布尔值。

boolean test(double value)

and()：该函数对当前对象和作为参数接收的对象进行 AND 运算，并返回新形成的谓词。该方法有一个默认实现。

default DoublePredicate and(DoublePredicate other)

negate()：该函数返回当前谓词的逆，即反转测试条件。该方法有一个默认实现。

default DoublePredicate negate()

or()：该函数对当前对象和作为参数接收的对象进行 OR 运算，并返回新形成的谓词。该方法有一个默认实现。

default DoublePredicate or(DoublePredicate other)

例子：

Java


// Java example to demonstrate DoublePredicate interface
import java.util.function.DoublePredicate;
public class DoublePredicateDemo {
    public static void main(String[] args)
    {
        // DoublePredicate to check square
        // of x is less than 100
        DoublePredicate db
            = (x) -> { return x * x < 100.0; };
        System.out.println("100 is less than 100 "
                           + db.test(10));
        DoublePredicate db3;
        // Test condition reversed
        db.negate();
        System.out.println("100 is greater than 100 "
                           + db.test(10));
        DoublePredicate db2 = (x) ->
        {
            double y = x * x;
            return y >= 36 && y < 1000;
        };
        // Test condition ANDed
        // with another predicate
        db3 = db.and(db2);
        System.out.println("81 is less than 100 "
                           + db3.test(9));
        db3 = db.or(db2);
        // Test condition ORed with another predicate
        System.out.println("49 is greater than 36"
                           + " and less than 100 "
                           + db3.test(7));
    }
}

输出：

100 is less than 100 false
100 is greater than 100 false
81 is less than 100 true
49 is greater than 36 and less than 100 true

参考： https://docs.oracle.com/javase/8/docs/api/java/util/function/DoublePredicate.html

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注：本文由纯净天空筛选整理自CharchitKapoor大神的英文原创作品 Java.util.function.DoublePredicate interface in Java with Examples。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。