guava ordering 类——迹忆客-ag捕鱼王app官网

ordering 可以看作是一个丰富的比较器，具有增强的链接功能、多种实用方法、多类型排序能力等。

类声明

以下是 com.google.common.collect.ordering 类的声明

@gwtcompatible
public abstract class ordering
   extends object
      implements comparator

类方法

方法继承

该类继承了以下类的方法 -

• java.lang.object

ordering 类示例

在 c:/> guava 中使用我们选择的任何编辑器创建以下 java 程序。

guavatester.java

import java.util.arraylist;
import java.util.collections;
import java.util.list;
import com.google.common.collect.ordering;
public class guavatester {
   public static void main(string args[]) {
      list numbers = new arraylist();
      
      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 names = new arraylist();
      
      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);
   }
}

验证结果

使用 javac 编译器编译类，如下所示

c:\guava>javac guavatester.java

现在运行 guavatester 以查看结果。

c:\guava>java guavatester

结果如下

input list: 
[5, 2, 15, 51, 53, 35, 45, 32, 43, 16]
sorted list: 
[2, 5, 15, 16, 32, 35, 43, 45, 51, 53]
======================
list is sorted: true
minimum: 2
maximum: 53
reverse: [53, 51, 45, 43, 35, 32, 16, 15, 5, 2]
null added to sorted list: 
[53, 51, 45, 43, 35, 32, 16, 15, 5, 2, null]
null first sorted list: 
[null, 2, 5, 15, 16, 32, 35, 43, 45, 51, 53]
======================
another list: 
[ram, shyam, mohan, sohan, ramesh, suresh, naresh, mahesh, null, vikas, deepak]
null first then reverse sorted list: 
[vikas, suresh, sohan, shyam, ramesh, ram, naresh, mohan, mahesh, deepak, null]