Java 中的缓冲区限制()方法，示例
原文:https://www . geesforgeks . org/buffer-limit-methods-in-Java-with-examples/
java.nio.Buffer 类的 limit() 方法用于设置该缓冲区的限制。如果该位置大于新限制，则将其设置为新限制。如果标记已定义并且大于新的限制，则丢弃该标记。
语法:
public Buffer limit(int newLimit)
返回值:这个方法返回这个缓冲区。
以下是举例说明 limit()方法的示例:
示例 1:
// Java program to demonstrate
// limit() method
import java.nio.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// defining and allocating ByteBuffer
// using allocate() method
ByteBuffer byteBuffer
= ByteBuffer.allocate(4);
// put byte value in byteBuffer
// using put() method
byteBuffer.put((byte)20);
byteBuffer.put((byte)30);
// Typecast byteBuffer to buffer
Buffer buffer = (Buffer)byteBuffer;
// print the byte buffer
System.out.println("Buffer before operation: "
+ Arrays.toString(
(byte[])buffer.array())
+ "\nPosition: "
+ buffer.position()
+ "\nLimit: "
+ buffer.limit());
// Limit the Buffer
// using limit() method
buffer.limit(1);
// print the buffer
System.out.println("\nBuffer after operation: "
+ Arrays.toString(
(byte[])buffer.array())
+ "\nPosition: "
+ buffer.position()
+ "\nLimit: "
+ buffer.limit());
}
}
输出:
Buffer before operation: [20, 30, 0, 0]
Position: 2
Limit: 4
Buffer after operation: [20, 30, 0, 0]
Position: 1
Limit: 1
示例 2:
// Java program to demonstrate
// limit() method
import java.nio.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// defining and allocating ByteBuffer
// using allocate() method
ByteBuffer byteBuffer
= ByteBuffer.allocate(5);
// put byte value in byteBuffer
// using put() method
byteBuffer.put((byte)20);
byteBuffer.put((byte)30);
byteBuffer.put((byte)40);
// Typecast byteBuffer to buffer
Buffer buffer = (Buffer)byteBuffer;
// mark will be going to discarded by limit()
buffer.mark();
// print the buffer
System.out.println("Buffer before operation: "
+ Arrays.toString(
(byte[])buffer.array())
+ "\nPosition: "
+ buffer.position()
+ "\nLimit: "
+ buffer.limit());
// Limit the Buffer
// using limit() method
buffer.limit(4);
// print the buffer
System.out.println("\nBuffer after operation: "
+ Arrays.toString(
(byte[])buffer.array())
+ "\nPosition: "
+ buffer.position()
+ "\nLimit: "
+ buffer.limit());
}
}
输出:
Buffer before operation: [20, 30, 40, 0, 0]
Position: 3
Limit: 5
Buffer after operation: [20, 30, 40, 0, 0]
Position: 3
Limit: 4
参考:https://docs . Oracle . com/javase/9/docs/API/Java/nio/buffer . html # limit-int-
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