Java 中的 ShortBuffer arrayOffset()方法，示例
原文:https://www . geesforgeks . org/short buffer-arrayoffset-method-in-Java-with-examples/
java.nio.ShortBuffer 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 int arrayOffset()
返回值:该方法返回该缓冲区数组中第一个缓冲区元素的偏移量。
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 ShortBuffer
int capacity = 10;
// Creating the ShortBuffer
try {
// creating object of shortbuffer
// and allocating size capacity
ShortBuffer sb = ShortBuffer.allocate(capacity);
// putting the value in shortbuffer
sb.put((short)856);
sb.put(2, (short)961);
// print the ShortBuffer
System.out.println("ShortBuffer: "
+ Arrays.toString(sb.array()));
// print the arrayOffset
System.out.println("arrayOffset: "
+ sb.arrayOffset());
}
catch (IllegalArgumentException e) {
System.out.println("IllegalArgumentException catched");
}
catch (ReadOnlyBufferException e) {
System.out.println("Exception throws" + e);
}
}
}
Output:
ShortBuffer: [856, 0, 961, 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 ShortBuffer
int capacity = 10;
// Creating the ShortBuffer
try {
// creating object of shortbuffer
// and allocating size capacity
ShortBuffer sb = ShortBuffer.allocate(capacity);
// putting the value in shortbuffer
sb.put((short)856);
sb.put(2, (short)961);
sb.rewind();
// Creating a read-only copy of ShortBuffer
// using asReadOnlyBuffer() method
ShortBuffer sb1 = sb.asReadOnlyBuffer();
// print the ShortBuffer
System.out.print("Read only buffer : ");
while (sb1.hasRemaining())
System.out.print(sb1.get() + ", ");
// next line
System.out.println("");
// print the arrayOffset
System.out.println("\nTry to print the array offset"
+ " of read only buffer");
System.out.println("arrayOffset: " + sb1.arrayOffset());
}
catch (IllegalArgumentException e) {
System.out.println("Exception throws: " + e);
}
catch (ReadOnlyBufferException e) {
System.out.println("Exception throws: " + e);
}
}
}
Output:
Read only buffer : 856, 0, 961, 0, 0, 0, 0, 0, 0, 0,
Try to print the array offset of read only buffer
Exception throws: java.nio.ReadOnlyBufferException
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