Java 中的 IntBuffer hasArray()方法
原文:https://www . geesforgeks . org/int buffer-hasarray-method-in-Java/
java.nio.IntBuffer 类的 hasArray() 方法用于确保给定的缓冲区是否由可访问的 int 数组支持。如果该缓冲区有可访问的后备数组，则返回 true，否则返回 false。如果此方法返回 true，则可以安全地调用 array()和 arrayOffset()方法，因为它们在支持数组上工作。
语法:
public final boolean hasArray()
返回值:当且仅当该缓冲区由数组支持且不是只读时，该方法将返回真。否则返回假。
以下是说明 hasArray() 方法的例子:
示例 1: 当缓冲区由数组支持时
// Java program to demonstrate
// hasArray() method
import java.nio.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Declaring the capacity of the IntBuffer
int capacity = 10;
// Creating the IntBuffer
try {
// creating object of Intbuffer
// and allocating size capacity
IntBuffer ib = IntBuffer.allocate(capacity);
// putting the value in Intbuffer
ib.put(4);
ib.put(2, 9);
ib.rewind();
// checking IntBuffer ib is backed by array or not
boolean isArray = ib.hasArray();
// checking if else condition
if (isArray)
System.out.println("IntBuffer ib is"
+ " backed by array");
else
System.out.println("IntBuffer ib is"
+ " not backed by any array");
}
catch (IllegalArgumentException e) {
System.out.println("IllegalArgumentException catched");
}
catch (ReadOnlyBufferException e) {
System.out.println("ReadOnlyBufferException catched");
}
}
}
Output:
IntBuffer ib is backed by array
示例 2: 当缓冲区没有数组支持时
// Java program to demonstrate
// hasArray() method
import java.nio.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Declaring the capacity of the IntBuffer
int capacity = 10;
// Creating the IntBuffer
try {
// creating object of Intbuffer
// and allocating size capacity
IntBuffer ib = IntBuffer.allocate(capacity);
// putting the value in Intbuffer
ib.put(8);
ib.put(2, 9);
ib.rewind();
// Creating a read-only copy of IntBuffer
// using asReadOnlyBuffer() method
IntBuffer ib1 = ib.asReadOnlyBuffer();
// checking IntBuffer ib is backed by array or not
boolean isArray = ib1.hasArray();
// checking if else condition
if (isArray)
System.out.println("IntBuffer ib is"
+ " backed by array");
else
System.out.println("IntBuffer ib is"
+ " not backed by any array");
}
catch (IllegalArgumentException e) {
System.out.println("IllegalArgumentException catched");
}
catch (ReadOnlyBufferException e) {
System.out.println("ReadOnlyBufferException catched");
}
}
}
Output:
IntBuffer ib is not backed by any array
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