Java.util.BitSet 类方法在Java中的示例|设置 2

Methods discussed in this post:
                       BitSet class methods.
               /      /     |      |       \       \
           set()  xor()  clone() clear()  length()  cardinality()

我们强烈建议您参考下面的第 1 组作为先决条件。
Java中的BitSet类|设置 1

set() : Java.util.BitSet.set()方法是将指定索引处的位设置为指定值。
句法：

public void set(int bitpos)
public void set(int bitpos, boolean val)
Parameters:
bitpos : a bit index
val : a boolean value to set
Return: Nothing
Throws: IndexOutOfBoundsException - if the specified index is negative

clone() : Java.util.BitSet.clone()方法克隆一个 BitSet 生成一个与其相等的新 BitSet。位集的克隆是另一个位集，它具有与该位集完全相同的位设置为真。
句法：
```
public Object clone()
Return: a clone of this bit set
```

cardinality : Java.util.BitSet.cardinality()方法用于查找编号。 Bitset 中的元素。
句法：

public int cardinality()
Return: the number of bits set to true in this BitSet.

// Java program explaining BitSet class methods
// set(), clone(), cardinality()
import java.util.*;
public class NewClasss
{
    public static void main(String[] args)
    {
        BitSet bs1 = new BitSet();
        BitSet bs2 = new BitSet(8);
        BitSet bs3 = new BitSet();
  
        // assign values to bs1 using set()
        bs1.set(0);
        bs1.set(1);
        bs1.set(2);
        bs1.set(4);
  
        // assign values to bs2
        bs2.set(4);
        bs2.set(6);
        bs2.set(5);
  
        // Here we are using .clone() method to make
        // bs3 as bs1
        bs3 = (BitSet) bs1.clone();
  
        // Printing the 3 Bitsets
        System.out.println("bs1 : " + bs1);
        System.out.println("bs2 : " + bs2);
        System.out.println("bs3 cloned from bs1 : " + bs3);
  
        // Using .cardinality() method to print the no. of
        // elements of Bitset
        System.out.println("Cardinality of bs1 : " +
                                       bs1.cardinality());
        System.out.println("Cardinality of bs2 : " +
                                       bs2.cardinality());
    }
}

输出：

bs1 : {0, 1, 2, 4}
bs2 : {4, 5, 6}
bs3 cloned from bs1 : {0, 1, 2, 4}
Cardinality of bs1 : 4
Cardinality of bs2 : 3

clear() : Java.util.BitSet.clear()方法用于清除元素，即将所有Bitset 元素设置为false。
句法：

public void clear(int frompos,int topos)
public void clear(int bitIndex)
public void clear()
Parameters:
frompos - index of the first bit to be cleared
topos - index after the last bit to be cleared
bitIndex - the index of the bit to be cleared
Throws:
IndexOutOfBoundsException - if pos value is negative or frompos is larger than topos

xor() : Java.util.BitSet.xor()方法对位集执行逻辑异或操作。
此位集被修改，以便其中的位具有值 true 当且仅当：
- 该位最初的值为 true，而参数中的相应位的值为 false。
- 该位最初的值为 false，而参数中的相应位的值为 true。
句法：
```
public void xor(BitSet set)
Parameters:
set - the BitSet with which we need to perform operation
```

length() : Java.util.BitSet.length()方法返回返回位集的逻辑大小。
bitset 中最高设置位的索引加一。如果位集不包含设置位，则返回零。
句法：

public int length()
Returns:
the logical size of this BitSet

// Java program explaining BitSet class methods
//  xor(), length(), clear() methods
import java.util.*;
public class NewClass
{
    public static void main(String[] args)
    {
        BitSet bs1 = new BitSet();
        BitSet bs2 = new BitSet();
  
        // assign values to bs1 using set()
        bs1.set(7);
        bs1.set(1);
        bs1.set(2);
        bs1.set(4);
        bs1.set(3);
        bs1.set(6);
  
        // assign values to bs2
        bs2.set(4);
        bs2.set(6);
        bs2.set(3);
        bs2.set(9);
        bs2.set(2);
  
        // Printing the Bitsets
        System.out.println("bs1 : " + bs1);
        System.out.println("bs2 : " + bs2);
  
        // use of length() method
        System.out.println("use of length() : " + bs1.length());
  
        // use of xor() to perform logical Xor operation
        bs1.xor(bs2);
        System.out.println("Use of xor() : " + bs1);
        bs2.xor(bs1);
        System.out.println("Use of xor() : " + bs2);
  
        // clear from index 2 to index 4 in bs1
        bs2.clear(1, 2);
        System.out.println("bs2 after clear method : " + bs2);
  
        // clear complete Bitset
        bs1.clear();
        System.out.println("bs1 after clear method : " + bs1);
    }
}

输出：

bs1 : {1, 2, 3, 4, 6, 7}
bs2 : {2, 3, 4, 6, 9}
use of length() : 8
Use of xor() : {1, 7, 9}
Use of xor() : {1, 2, 3, 4, 6, 7}
bs2 after clear method : {2, 3, 4, 6, 7}
bs1 after clear method : {}

Java中的BitSet 类方法与示例|设置 3

参考：
https://docs.oracle.com/javase/7/docs/api/java Java