簡介：

Ordering(排序)可以被看作是一個豐富的比較具有增強功能的連結，多個實用方法，多型別排序功能等。

類宣告

以下是com.google.common.collect.Ordering<T>類的宣告：

@GwtCompatible
public abstract class Ordering<T>
   extends Object
      implements Comparator<T>

類方法

方法繼承

這個類從以下類繼承的方法：

• java.lang.Object

Ordering 示例

List<Integer> numbers = new ArrayList<Integer>();
        numbers.add(new Integer(5));
        numbers.add(new Integer(2));
        numbers.add(new Integer(15));
        numbers.add(new Integer(51));
        numbers.add(new Integer(53));
        numbers.add(new Integer(35));
        numbers.add(new Integer(45));
        numbers.add(new Integer(32));
        numbers.add(new Integer(43));
        numbers.add(new Integer(16));

        Ordering ordering = Ordering.natural();
        System.out.println("Input List: ");
        System.out.println(numbers);

        Collections.sort(numbers, ordering);
        System.out.println("Sorted List: ");
        System.out.println(numbers);

        System.out.println("======================");
        System.out.println("List is sorted: " + ordering.isOrdered(numbers));
        System.out.println("Minimum: " + ordering.min(numbers));
        System.out.println("Maximum: " + ordering.max(numbers));

        Collections.sort(numbers, ordering.reverse());
        System.out.println("Reverse: " + numbers);

        numbers.add(null);
        System.out.println("Null added to Sorted List: ");
        System.out.println(numbers);

        Collections.sort(numbers, ordering.nullsFirst());
        System.out.println("Null first Sorted List: ");
        System.out.println(numbers);
        System.out.println("======================");

        List<String> names = new ArrayList<String>();
        names.add("Ram");
        names.add("Shyam");
        names.add("Mohan");
        names.add("Sohan");
        names.add("Ramesh");
        names.add("Suresh");
        names.add("Naresh");
        names.add("Mahesh");
        names.add(null);
        names.add("Vikas");
        names.add("Deepak");

        System.out.println("Another List: ");
        System.out.println(names);

        Collections.sort(names, ordering.nullsFirst().reverse());
        System.out.println("Null first then reverse sorted list: ");
        System.out.println(names);

     List<People> peopleList = new ArrayList<People>() {{
            add(new People("A", 33));
            add(new People("B", 11));
            add(new People("C", 18));
        }};
        List<People> po = Lists.newArrayList();
        po.addAll(peopleList);
        Ordering<People> ordering = Ordering.natural().onResultOf(new Function<People, Comparable>() {
            @Override
            public Comparable apply(People people) {
                return people.getAge();
            }
        });

        for (People p : ordering.reverse().sortedCopy(po)) {
            System.out.println(MoreObjects.toStringHelper(p)
                    .add("name", p.getName())
                    .add("age", p.getAge())
            );
        }

結果：
People{name=A, age=33}
People{name=C, age=18}
People{name=B, age=11}

List<People> peopleList = new ArrayList<People>() {{
            add(new People("A", 33));
            add(new People("B", 11));
            add(new People("C", 18));
        }};

        Ordering<People> ordering = Ordering.usingToString().reverse().onResultOf(new Function<People, Comparable>() {
            @Override
            public Comparable apply(People people) {
                return people.getName();
            }
        });

        for (People p : ordering.sortedCopy(peopleList)) {
            System.out.println(MoreObjects.toStringHelper(p)
                    .add("name", p.getName())
                    .add("age", p.getAge())
            );
        }

結果：
People{name=C, age=18}
People{name=B, age=11}
People{name=A, age=33}

    List<People> peopleList = new ArrayList<People>() {{  
        add(new People("A", 33));  
        add(new People("B", 11));  
        add(new People("C", 18));  
    }};  
   
    Ordering<People> ordering = Ordering.from(new Comparator<People>() {  
        @Override  
        public int compare(People o1, People o2) {  
            return o1.getAge() - o2.getAge();  
        }  
    });  
   
    for (People p : ordering.sortedCopy(peopleList)) {  
        System.out.println(MoreObjects.toStringHelper(p)  
                        .add("name", p.getName())  
                        .add("age", p.getAge())  
        );  
    }  

結果：
People{name=B, age=11}  
People{name=C, age=18}  
People{name=A, age=33}