Java中的 CharBuffer allocate() 方法及示例

Java.nio.CharBuffer 类的allocate()方法用于在现有缓冲区旁边分配一个新的字符缓冲区。新缓冲区的位置将为零。它的极限将是它的容量。它的标记将是未定义的。并且它的每个元素都将被初始化为零。它将有一个支持数组，并且它的数组偏移量为零。

句法：

public static CharBuffer allocate(int capacity)

参数：此方法将新缓冲区的容量（以 char 为单位）作为参数。

返回值：此方法返回新的字符缓冲区。

异常：如果容量为负整数，此方法将引发IllegalArgumentException 。

下面的程序说明了 allocate() 方法：

示例 1：

Java

// Java program to demonstrate
// allocate() method
  
import java.nio.*;
import java.util.*;
  
public class GFG {
    public static void main(String[] args)
    {
  
        // Declaring the capacity of the CharBuffer
        char capacity = 10;
  
        // Creating the CharBuffer
  
        // creating object of Charbuffer
        // and allocating size capacity
        CharBuffer fb = CharBuffer.allocate(capacity);
  
        // putting the value in charbuffer
        fb.put('a');
        fb.put(3, 'b');
  
        // Printing the CharBuffer
        System.out.println("ChartBuffer: "
                           + Arrays.toString(fb.array()));
    }
}

输出：

ChartBuffer: [a, , , b, , , , , , ]

示例 2：演示 IllegalArgumentException

Java

// Java program to demonstrate
// allocate() method
  
import java.nio.*;
import java.util.*;
  
public class GFG {
    public static void main(String[] args)
    {
  
        // Declaring the capacity of the CharBuffer
        // by negative integer
        int capacity = -10;
  
        // Creating the CharBuffer
        try {
  
            // creating object of CharBuffer
            // and allocating size with negative integer
            System.out.println("Trying to allocate a negative integer");
  
            CharBuffer fb = CharBuffer.allocate(capacity);
        }
        catch (IllegalArgumentException e) {
            System.out.println("Exception thrown: " + e);
        }
    }
}

输出：

Trying to allocate a negative integer
Exception thrown: java.lang.IllegalArgumentException