Java中的Java .util.BitSet.clear()

clear() 方法有三种变体：

1. clear() : clear() 方法将此 BitSet 中的所有位设置为 false。

   public void clear()
   Return Value
   This method does not return a value.
   

   // Java code to demonstrate the working
   // of clear() in BitSet
   import java.util.*;
   public class BitClr1 {
   public static void main(String[] args)
       {
     
           // Declaring Bitset
           BitSet bset = new BitSet(8);
     
           // assigning values to bitset
           for (int i = 0; i < 5; i++)
               bset.set(i);
     
           // printing original bitset
           System.out.println
           ("The bitset before clear() operation is : " + bset);
     
           // using clear() to clear contents of bitset
           bset.clear();
     
           // printing bitset after clear() operation
           // empty bitset
           System.out.println
           ("The bitset after clear() operation is : " + bset);
       }
   }
   

   输出：

   The bitset before clear() operation is : {0, 1, 2, 3, 4}
   The bitset after clear() operation is : {}
   

2. clear(int pos) : clear(int pos) 方法将索引指定的位设置为 false。即从 bitset 中删除。

   public void clear(int pos)
   Parameters
      pos : the index of the bit to be cleared.
   Return Value
   This method does not return a value.
   Exception
      IndexOutOfBoundsException : if the specified index is negative.
   

   // Java code to demonstrate the working
   // of clear(int pos) in BitSet
   import java.util.*;
   public class BitClr2 {
   public static void main(String[] args)
       {
     
           // Declaring Bitset
           BitSet bset = new BitSet(8);
     
           // assigning values to bitset
           for (int i = 0; i < 5; i++)
               bset.set(i);
     
           // printing original bitset
           System.out.println
           ("The bitset before clear(pos) operation is : " + bset);
     
           // using clear(pos) to clear element at specified position
           bset.clear(3);
     
           // printing bitset after clear(pos) operation
           // removes 3
           System.out.println
           ("The bitset after clear(pos) operation is : " + bset);
       }
   }
   

   输出：

   The bitset before clear(pos) operation is : {0, 1, 2, 3, 4}
   The bitset after clear(pos) operation is : {0, 1, 2, 4}
   

3. clear(int frompos, int topos) ： clear(int frompos, int topos) 方法将指定 frompos（包括）到指定 topos（不包括）的位设置为 false，即在范围内执行删除。

   public void clear(int frompos, int topos)
   Parameters
       frompos : index of the first bit to be cleared
       topos : index of the last bit to be cleared
   Return Value
   This method does not return a value.
   Exception
       IndexOutOfBoundsException: if frompos is negative, 
   or topos is negative, or frompos is larger than topos.
   

   // Java code to demonstrate the working
   // of clear(int frompos, int topos) in BitSet
   import java.util.*;
   public class BitClr3 {
   public static void main(String[] args)
       {
     
           // Declaring Bitset
           BitSet bset = new BitSet(8);
     
           // assigning values to bitset
           for (int i = 0; i < 5; i++)
               bset.set(i);
     
           // printing original bitset
           System.out.println
           ("The bitset before clear(frompos, topos) operation is : " + bset);
     
           // using clear(frompos, topos) to clear elements in range
           bset.clear(2, 4);
     
           // printing bitset after clear(frompos, topos) operation
           // removes 2, 3
           System.out.println
           ("The bitset after clear(frompos, topos) operation is : " + bset);
       }
   }
   

   输出：

   The bitset before clear(frompos, topos) operation is : {0, 1, 2, 3, 4}
   The bitset after clear(frompos, topos) operation is : {0, 1, 4}