Java Java.util.BitSet.clear()用法及代碼示例

有三clear()方法的變體：

1. clear()：clear()方法將此BitSet中的所有位設置為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); 
       } 
   }

   輸出：

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

2. clear(int pos)：clear(int pos)方法將索引指定的位設置為false。即從位集中刪除。

   public void clear(int pos)
   參數
      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); 
       } 
   }

   輸出：

   
   

   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)方法將指定的frompos(包括)到指定的topos(不包括)的位設置為false，即在一定範圍內執行刪除操作。

   public void clear(int frompos, int topos)
   參數
       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); 
       } 
   }

   輸出：

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