Java 中的 DoubleBuffer asReadOnlyBuffer()方法，示例
原文:https://www . geesforgeks . org/double buffer-as readonly buffer-in-Java-method-with-examples/
类的 asReadOnlyBuffer() 方法用于用这个缓冲区的内容创建一个新的只读双缓冲区。新缓冲区是该缓冲区的副本。因此，对此缓冲区内容所做的更改将在新缓冲区中可见。
由于新缓冲区是只读的，因此不允许对其内容进行任何修改。两个缓冲器的位置、极限和标记值将是独立的。新缓冲区的容量、限制、位置和标记值将与该缓冲区相同。如果此缓冲区本身是只读的，则此方法的行为方式与复制方法完全相同。
语法:
public abstract DoubleBuffer asReadOnlyBuffer()
返回值:该方法返回新的只读双缓冲区，内容与该缓冲区相同。
下面是说明 asReadOnlyBuffer()方法的示例:
例 1:
// Java program to demonstrate
// asReadOnlyBuffer() method
import java.nio.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Declaring the capacity of the DoubleBuffer
int capacity = 10;
// Creating the DoubleBuffer
try {
// creating object of floatbuffer
// and allocating size capacity
DoubleBuffer db = DoubleBuffer.allocate(capacity);
// putting the value in floatbuffer
db.put(8.56);
db.put(2, 9.61);
db.rewind();
// print the DoubleBuffer
System.out.println("Original DoubleBuffer: "
+ Arrays.toString(db.array()));
// Creating a read-only copy of DoubleBuffer
// using asReadOnlyBuffer() method
DoubleBuffer floatBuffer = db.asReadOnlyBuffer();
// print the DoubleBuffer
System.out.print("\nReadOnlyBuffer DoubleBuffer: ");
while (floatBuffer.hasRemaining())
System.out.print(floatBuffer.get() + ", ");
}
catch (IllegalArgumentException e) {
System.out.println("IllegalArgumentException catched");
}
catch (ReadOnlyBufferException e) {
System.out.println("ReadOnlyBufferException catched");
}
}
}
Output:
Original DoubleBuffer: [8.56, 0.0, 9.61, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
ReadOnlyBuffer DoubleBuffer: 8.56, 0.0, 9.61, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,
例 2:
// Java program to demonstrate
// asReadOnlyBuffer() method
import java.nio.*;
import java.util.*;
public class GFG {
public static void main(String[] args) throws Exception
{
// Declaring the capacity of the db
int capacity1 = 10;
// Declaring the capacity of the db1
int capacity2 = 5;
// Creating the DoubleBuffer
try {
//
// db
//
// creating object of Doublebuffer db
// and allocating size capacity
DoubleBuffer db = DoubleBuffer.allocate(capacity1);
// putting the value in db
db.put(8.56);
db.put(2, 9.61);
db.rewind();
// print the DoubleBuffer
System.out.println("DoubleBuffer db: "
+ Arrays.toString(db.array()));
//
// db1
//
// creating object of Doublebuffer db1
// and allocating size capacity
DoubleBuffer db1 = DoubleBuffer.allocate(capacity2);
// putting the value in db1
db1.put(1, 4.56);
db1.put(2, 6.45);
db1.rewind();
// print the DoubleBuffer
System.out.println("\nDoubleBuffer db1: "
+ Arrays.toString(db1.array()));
// Creating a read-only copy of DoubleBuffer
// using asReadOnlyBuffer() method
DoubleBuffer readOnlyDb = db.asReadOnlyBuffer();
// print the DoubleBuffer
System.out.print("\nReadOnlyBuffer DoubleBuffer: ");
while (readOnlyDb.hasRemaining())
System.out.print(readOnlyDb.get() + ", ");
// try to change readOnlyDb
System.out.println("\n\nTrying to get the array"
+ " from ReadOnlyDb for editing");
Arrays.toString(readOnlyDb.array());
}
catch (IllegalArgumentException e) {
System.out.println("IllegalArgumentException catched");
}
catch (ReadOnlyBufferException e) {
System.out.println("Exception thrown: " + e);
}
}
}
Output:
DoubleBuffer db: [8.56, 0.0, 9.61, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
DoubleBuffer db1: [0.0, 4.56, 6.45, 0.0, 0.0]
ReadOnlyBuffer DoubleBuffer: 8.56, 0.0, 9.61, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,
Trying to get the array from ReadOnlyDb for editing
Exception thrown: java.nio.ReadOnlyBufferException
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