/*

  * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.

  * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.

  */

 package java.util.function;

 import java.util.Objects;

 /**

  * Represents a predicate (boolean-valued function) of one argument.

  *

  * <p>This is a <a href="package-summary.html">functional interface</a>

  * whose functional method is {@link #test(Object)}.

  *

  * @param <T> the type of the input to the predicate

  *

  * @since 1.8

  */

 @FunctionalInterface

 public interface Predicate<T> {

     /**

      * Evaluates this predicate on the given argument.

      *

      * @param t the input argument

      * @return {@code true} if the input argument matches the predicate,

      * otherwise {@code false}

      */

     boolean test(T t);

     /**

      * Returns a composed predicate that represents a short-circuiting logical

      * AND of this predicate and another.  When evaluating the composed

      * predicate, if this predicate is {@code false}, then the {@code other}

      * predicate is not evaluated.

      *

      * <p>Any exceptions thrown during evaluation of either predicate are relayed

      * to the caller; if evaluation of this predicate throws an exception, the

      * {@code other} predicate will not be evaluated.

      *

      * @param other a predicate that will be logically-ANDed with this

      *              predicate

      * @return a composed predicate that represents the short-circuiting logical

      * AND of this predicate and the {@code other} predicate

      * @throws NullPointerException if other is null

      */

     default Predicate<T> and(Predicate<? super T> other) {

         Objects.requireNonNull(other);

         return (t) -> test(t) && other.test(t);

     }

     /**

      * Returns a predicate that represents the logical negation of this

      * predicate.

      *

      * @return a predicate that represents the logical negation of this

      * predicate

      */

     default Predicate<T> negate() {

         return (t) -> !test(t);

     }

     /**

      * Returns a composed predicate that represents a short-circuiting logical

      * OR of this predicate and another.  When evaluating the composed

      * predicate, if this predicate is {@code true}, then the {@code other}

      * predicate is not evaluated.

      *

      * <p>Any exceptions thrown during evaluation of either predicate are relayed

      * to the caller; if evaluation of this predicate throws an exception, the

      * {@code other} predicate will not be evaluated.

      *

      * @param other a predicate that will be logically-ORed with this

      *              predicate

      * @return a composed predicate that represents the short-circuiting logical

      * OR of this predicate and the {@code other} predicate

      * @throws NullPointerException if other is null

      */

     default Predicate<T> or(Predicate<? super T> other) {

         Objects.requireNonNull(other);

         return (t) -> test(t) || other.test(t);

     }

     /**

      * Returns a predicate that tests if two arguments are equal according

      * to {@link Objects#equals(Object, Object)}.

      *

      * @param <T> the type of arguments to the predicate

      * @param targetRef the object reference with which to compare for equality,

      *               which may be {@code null}

      * @return a predicate that tests if two arguments are equal according

      * to {@link Objects#equals(Object, Object)}

      */

     static <T> Predicate<T> isEqual(Object targetRef) {

         return (null == targetRef)

                 ? Objects::isNull

                 : object -> targetRef.equals(object);

     }

 }

 package org.htsg;

 import java.util.ArrayList;

 import java.util.List;

 import java.util.Objects;

 import java.util.function.Predicate;

 /**

  * @author HTSG

  */

 public class PredicateTest {

     public static void main(String[] args) {

         // 添加十个学生

         List<Student> studentList = new ArrayList<>(10);

         for (int i = 0; i < 10; i++) {

             studentList.add(new Student("student" + i, 10 + i));

         }

         // 获取年龄大于15的学生

         // [Student{name='student6', age=16}, Student{name='student7', age=17}, Student{name='student8', age=18}, Student{name='student9', age=19}]

         List<Student> filteredStudents = test(studentList, PredicateTest::filterAge1);

         System.out.println(filteredStudents);

         // 获取年龄大于15并且名字叫 "student7" 的学生

         // [Student{name='student7', age=17}]

         filteredStudents = and(studentList, PredicateTest::filterAge1, PredicateTest::filterName);

         System.out.println(filteredStudents);

         // 获取年龄不大于15的学生

         // [Student{name='student0', age=10}, Student{name='student1', age=11}, Student{name='student2', age=12}, Student{name='student3', age=13}, Student{name='student4', age=14}, Student{name='student5', age=15}]

         filteredStudents = negate(studentList, PredicateTest::filterAge1);

         System.out.println(filteredStudents);

         // 获取年龄不大于15或名字叫 "student7" 的学生

         // [Student{name='student0', age=10}, Student{name='student1', age=11}, Student{name='student2', age=12}, Student{name='student3', age=13}, Student{name='student4', age=14}, Student{name='student5', age=15}, Student{name='student7', age=17}]

         filteredStudents = or(studentList, PredicateTest::filterAge2, PredicateTest::filterName);

         System.out.println(filteredStudents);

         // 获取和目标学生属性值相同的学生列表

         // [Student{name='student1', age=11}]

         filteredStudents = isEqual(studentList, new Student("student1", 11));

         System.out.println(filteredStudents);

     }

     public static boolean filterAge1(Student student) {

         return student.getAge() > 15;

     }

     public static boolean filterAge2(Student student) {

         return student.getAge() <= 15;

     }

     public static boolean filterName(Student student) {

         return "student7".equals(student.getName());

     }

     public static List<Student> test(List<Student> students, Predicate<Student> pre) {

         List<Student> result = new ArrayList<>(10);

         for (Student student : students) {

             if (pre.test(student)) {

                 result.add(student);

             }

         }

         return result;

     }

     public static List<Student> and(List<Student> students, Predicate<Student> pre1, Predicate<Student> pre2) {

         List<Student> result = new ArrayList<>(10);

         for (Student student : students) {

             if (pre1.and(pre2).test(student)) {

                 result.add(student);

             }

         }

         return result;

     }

     public static List<Student> negate(List<Student> students, Predicate<Student> pre) {

         List<Student> result = new ArrayList<>(10);

         for (Student student : students) {

             if (pre.negate().test(student)) {

                 result.add(student);

             }

         }

         return result;

     }

     public static List<Student> or(List<Student> students, Predicate<Student> pre1, Predicate<Student> pre2) {

         List<Student> result = new ArrayList<>(10);

         for (Student student : students) {

             if (pre1.or(pre2).test(student)) {

                 result.add(student);

             }

         }

         return result;

     }

     public static List<Student> isEqual(List<Student> students, Student student) {

         List<Student> result = new ArrayList<>(10);

         for (Student studentTemp : students) {

             if (Predicate.isEqual(student).test(studentTemp)) {

                 result.add(studentTemp);

             }

         }

         return result;

     }

     // 创建静态内部类

     public static class Student {

         private String name;

         private int age;

         public Student() {

         }

         public Student(String name, int age) {

             this.name = name;

             this.age = age;

         }

         public String getName() {

             return name;

         }

         public void setName(String name) {

             this.name = name;

         }

         public int getAge() {

             return age;

         }

         public void setAge(int age) {

             this.age = age;

         }

         @Override

         public String toString() {

             return "Student{" +

                     "name='" + name + '\'' +

                     ", age=" + age +

                     '}';

         }

         @Override

         public boolean equals(Object o) {

             if (this == o) {

                 return true;

             }

             if (o == null || getClass() != o.getClass()) {

                 return false;

             }

             Student student = (Student) o;

             return age == student.age &&

                     Objects.equals(name, student.name);

         }

     }

 }