Java 中的 LongBuffer arrayOffset()方法
原文:https://www . geesforgeks . org/longbuffer-arrayoffset-method-in-Java/
java.nio.LongBuffer 类的 arrayOffset() 方法用于返回缓冲区第一个元素在缓冲区后备数组中的偏移量。这意味着如果这个缓冲区由一个数组支持，那么缓冲区位置 p 对应于数组索引 p + arrayOffset()。
为了检查这个缓冲区是否有后备数组，可以使用 hasArray() 方法。它确保这个缓冲区有一个可访问的后备数组。
语法:
public final Long arrayOffset()
返回值:该方法返回该缓冲区数组中缓冲区第一个元素的偏移量。
异常:如果此缓冲区由数组支持但为只读，则此方法将引发readonlybufferrexception
下面的程序说明了 arrayOffset() 方法。
程序 1:
// Java program to demonstrate
// arrayOffset() method
import java.nio.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Declaring the capacity of the LongBuffer
int capacity = 10;
// Creating the LongBuffer
try {
// creating object of Longbuffer
// and allocating size capacity
LongBuffer ib = LongBuffer.allocate(capacity);
// putting the value in Longbuffer
ib.put(8);
ib.put(2, 9);
// prLong the LongBuffer
System.out.println("LongBuffer: "
+ Arrays.toString(ib.array()));
// prLong the arrayOffset
System.out.println("arrayOffset: "
+ ib.arrayOffset());
}
catch (IllegalArgumentException e) {
System.out.println("IllegalArgumentException catched");
}
catch (ReadOnlyBufferException e) {
System.out.println("Exception throws" + e);
}
}
}
Output:
LongBuffer: [8, 0, 9, 0, 0, 0, 0, 0, 0, 0]
arrayOffset: 0
程序 2: 演示 ReadOnlyBufferException。
// Java program to demonstrate
// arrayOffset() method
import java.nio.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Declaring the capacity of the LongBuffer
int capacity = 10;
// Creating the LongBuffer
try {
// creating object of Longbuffer
// and allocating size capacity
LongBuffer ib = LongBuffer.allocate(capacity);
// putting the value in Longbuffer
ib.put(8);
ib.put(2, 9);
ib.rewind();
// Creating a read-only copy of LongBuffer
// using asReadOnlyBuffer() method
LongBuffer ib1 = ib.asReadOnlyBuffer();
// prLong the LongBuffer
System.out.print("Read only buffer : ");
while (ib1.hasRemaining())
System.out.print(ib1.get() + ", ");
// next line
System.out.println("");
// prLong the arrayOffset
System.out.println("\nTry to prLong the array offset"
+ " of read only buffer");
System.out.println("arrayOffset: " + ib1.arrayOffset());
}
catch (IllegalArgumentException e) {
System.out.println("Exception throws: " + e);
}
catch (ReadOnlyBufferException e) {
System.out.println("Exception throws: " + e);
}
}
}
Output:
Read only buffer : 8, 0, 9, 0, 0, 0, 0, 0, 0, 0,
Try to prLong the array offset of read only buffer
Exception throws: java.nio.ReadOnlyBufferException
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