Guava Range类 - Guava教程

Range 表示一个间隔或一个序列。它被用于获取一组数字/串在一个特定范围之内。

类声明

以下是com.google.common.collect.Range<C>类的声明：

@GwtCompatible
public final class Range<C extends Comparable>
   extends Object
      implements Predicate<C>, Serializable

方法

方法继承

这个类从以下类继承的方法：

• java.lang.Object

Range 例子

选择使用任何编辑器创建以下java程序在 C:/> Guava

GuavaTester.java

import com.google.common.collect.ContiguousSet;
import com.google.common.collect.DiscreteDomain;
import com.google.common.collect.Range;
import com.google.common.primitives.Ints;

public class GuavaTester {

   public static void main(String args[]){
      GuavaTester tester = new GuavaTester();
      tester.testRange();
   }

   private void testRange(){

      //create a range [a,b] = { x | a <= x <= b}
      Range<Integer> range1 = Range.closed(0, 9);    
      System.out.print("[0,9] : ");
      printRange(range1);        
      System.out.println("5 is present: " + range1.contains(5));
      System.out.println("(1,2,3) is present: " + range1.containsAll(Ints.asList(1, 2, 3)));
      System.out.println("Lower Bound: " + range1.lowerEndpoint());
      System.out.println("Upper Bound: " + range1.upperEndpoint());

      //create a range (a,b) = { x | a < x < b}
      Range<Integer> range2 = Range.open(0, 9);
      System.out.print("(0,9) : ");
      printRange(range2);

      //create a range (a,b] = { x | a < x <= b}
      Range<Integer> range3 = Range.openClosed(0, 9);
      System.out.print("(0,9] : ");
      printRange(range3);

      //create a range [a,b) = { x | a <= x < b}
      Range<Integer> range4 = Range.closedOpen(0, 9);
      System.out.print("[0,9) : ");
      printRange(range4);

      //create an open ended range (9, infinity
      Range<Integer> range5 = Range.greaterThan(9);
      System.out.println("(9,infinity) : ");
      System.out.println("Lower Bound: " + range5.lowerEndpoint());
      System.out.println("Upper Bound present: " + range5.hasUpperBound());

      Range<Integer> range6 = Range.closed(3, 5);    
      printRange(range6);

      //check a subrange [3,5] in [0,9]
      System.out.println("[0,9] encloses [3,5]:" + range1.encloses(range6));

      Range<Integer> range7 = Range.closed(9, 20);    
      printRange(range7);
      //check ranges to be connected        
      System.out.println("[0,9] is connected [9,20]:" + range1.isConnected(range7));

      Range<Integer> range8 = Range.closed(5, 15);    

      //intersection
      printRange(range1.intersection(range8));

      //span
      printRange(range1.span(range8));
   }

   private void printRange(Range<Integer> range){        
      System.out.print("[ ");
      for(int grade : ContiguousSet.create(range, DiscreteDomain.integers())) {
         System.out.print(grade +" ");
      }
      System.out.println("]");
   }
}

验证结果

使用javac编译器编译如下类

C:\Guava>javac GuavaTester.java

现在运行GuavaTester看到的结果

C:\Guava>java GuavaTester

看到结果。

[0,9] : [ 0 1 2 3 4 5 6 7 8 9 ]
5 is present: true
(1,2,3) is present: true
Lower Bound: 0
Upper Bound: 9
(0,9) : [ 1 2 3 4 5 6 7 8 ]
(0,9] : [ 1 2 3 4 5 6 7 8 9 ]
[0,9) : [ 0 1 2 3 4 5 6 7 8 ]
(9,infinity) : 
Lower Bound: 9
Upper Bound present: false
[ 3 4 5 ]
[0,9] encloses [3,5]:true
[ 9 10 11 12 13 14 15 16 17 18 19 20 ]
[0,9] is connected [9,20]:true
[ 5 6 7 8 9 ]
[ 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 ]