Java中的DoubleBuffer compareTo() 方法示例

Java.nio.DoubleBuffer类的compareTo()方法用于将一个缓冲区与另一个缓冲区进行比较。通过按字典顺序比较它们的剩余元素序列来比较两个双缓冲区，而不考虑每个序列在其相应缓冲区中的起始位置。就像调用 Double.compare(double, double) 一样比较浮点元素对，除了 -0.0 和 0.0 被认为是相等的。此方法认为 Double.NaN 等于其自身并且大于所有其他双精度值（包括 Double.POSITIVE_INFINITY）。双缓冲区无法与任何其他类型的对象进行比较。

句法：

public int compareTo(DoubleBuffer that)

参数：此方法将双缓冲区对象作为参数，与此缓冲区进行比较。

返回值：此方法返回负整数、零或正整数，因为此缓冲区小于、等于或大于给定缓冲区。

以下是说明 compareTo() 方法的示例：

示例 1：当两个 DoubleBuffer 相等时。

// Java program to demonstrate
// compareTo() method
  
import java.nio.*;
import java.util.*;
  
public class GFG {
  
    public static void main(String[] args)
    {
  
        // Declaring the capacity of the db
        int capacity1 = 3;
  
        // Creating the DoubleBuffer
        try {
  
            // creating object of Doublebuffer db
            // and allocating size capacity
            DoubleBuffer db = DoubleBuffer.allocate(capacity1);
  
            // putting the value in db
            db.put(9.56);
            db.put(7.61);
            db.put(4.61);
  
            // revind the Double buffer
            db.rewind();
  
            // print the DoubleBuffer
            System.out.println("DoubleBuffer db: "
                               + Arrays.toString(db.array()));
  
            // creating object of Doublebuffer db1
            // and allocating size capacity
            DoubleBuffer db1 = DoubleBuffer.allocate(capacity1);
  
            // putting the value in db1
            db1.put(9.56);
            db1.put(7.61);
            db1.put(4.61);
  
            // revind the Double buffer
            db1.rewind();
  
            // print the DoubleBuffer
            System.out.println("DoubleBuffer db1: "
                               + Arrays.toString(db1.array()));
  
            // compare both buffer and store the value into integer
            int i = db.compareTo(db1);
  
            // if else condition
            if (i == 0)
                System.out.println("\nboth buffer are lexicographically equal");
            else if (i >= 0)
                System.out.println("\ndb is lexicographically greater than db1");
            else
                System.out.println("\ndb is lexicographically less than db1");
        }
  
        catch (IllegalArgumentException e) {
            System.out.println("Exception throws : " + e);
        }
  
        catch (ReadOnlyBufferException e) {
            System.out.println("Exception throws : " + e);
        }
    }
}

输出：

DoubleBuffer db: [9.56, 7.61, 4.61]
DoubleBuffer db1: [9.56, 7.61, 4.61]

both buffer are lexicographically equal

示例 2：当此 DoubleBuffer 大于传递的 DoubleBuffer

// Java program to demonstrate
// compareTo() method
  
import java.nio.*;
import java.util.*;
  
public class GFG {
  
    public static void main(String[] args)
    {
  
        // Declaring the capacity of the db
        int capacity1 = 3;
  
        // Creating the DoubleBuffer
        try {
  
            // creating object of Doublebuffer db
            // and allocating size capacity
            DoubleBuffer db = DoubleBuffer.allocate(capacity1);
  
            // putting the value in db
            db.put(9.56);
            db.put(7.61);
            db.put(4.61);
  
            // revind the Double buffer
            db.rewind();
  
            // print the DoubleBuffer
            System.out.println("DoubleBuffer db: "
                               + Arrays.toString(db.array()));
  
            // creating object of Doublebuffer db1
            // and allocating size capacity
            DoubleBuffer db1 = DoubleBuffer.allocate(capacity1);
  
            // putting the value in db1
            db1.put(8.56);
            db1.put(7.61);
            db1.put(4.61);
  
            // revind the Double buffer
            db1.rewind();
  
            // print the DoubleBuffer
            System.out.println("DoubleBuffer db1: "
                               + Arrays.toString(db1.array()));
  
            // compare both buffer and store the value into integer
            int i = db.compareTo(db1);
  
            // if else condition
            if (i == 0)
                System.out.println("\nboth buffer are lexicographically equal");
            else if (i >= 0)
                System.out.println("\ndb is lexicographically greater than db1");
            else
                System.out.println("\ndb is lexicographically less than db1");
        }
  
        catch (IllegalArgumentException e) {
            System.out.println("Exception throws : " + e);
        }
  
        catch (ReadOnlyBufferException e) {
            System.out.println("Exception throws : " + e);
        }
    }
}

输出：

DoubleBuffer db: [9.56, 7.61, 4.61]
DoubleBuffer db1: [8.56, 7.61, 4.61]

db is lexicographically greater than db1