Java8 Comparator源码演示及解析

/**
 * 关于 java8 中的 Comparator 排序方法
 */
public class CompareController2 {

  public static void main(String[] args) {

    /**
     * 对常见的list等进行升序和降序
     */
    List<Integer> list = Arrays.asList(10,133,34,546,53,345);
    // 自然顺序，升序
    list.sort(Comparator.naturalOrder());
    System.out.println(list);
    // 降序
    list.sort(Comparator.reverseOrder());
    System.out.println(list);

    /**
     * 对于 对象的排序
     */
    List<Students> studentsList = new ArrayList<>();
    studentsList.add(new Students("zhangSan", 28, "beiJing"));
    studentsList.add(new Students("liSi", 25, "shangHai"));
    studentsList.add(new Students("wangWu", 22));

    studentsList.sort(Comparator.comparing(Students::getName));
    System.out.println("按照姓名升序：" + studentsList);

    studentsList.sort(Comparator.comparing(Students::getAge).reversed());
    System.out.println("按照年龄降序：" + studentsList);

    studentsList.sort(Comparator.comparing(Students::getAddress, Comparator.nullsLast(String::compareTo)).reversed());
    System.out.println("按照地址降序，若有空，放到最前面：" + studentsList);

    studentsList.sort(Comparator.comparing(Students::getAddress, Comparator.nullsFirst(String::compareTo)).reversed());
    System.out.println("按照地址降序，若有空，放到最后面：" + studentsList);

    studentsList.sort(Comparator.comparing(Students::getAddress, Comparator.nullsLast(String::compareTo)).reversed().thenComparing(Students::getAge));
    System.out.println("按照地址降序，若有空，放到最前面，然后再按照年龄升序：" + studentsList);

  }
}