Java CharBuffer charAt()用法及代碼示例

java.nio.CharBuffer類的charAt()方法用於讀取相對於當前位置的給定索引處的字符。

用法:

public final char charAt(int index)

參數：此方法獲取要讀取的字符相對於位置的索引；必須為非負且小於remaining()。

返回值：此方法返回索引position() +索引處的字符。

異常：如果索引的前提條件不成立，則此方法將引發IndexOutOfBoundsException。

以下示例說明了charAt(int index)方法：

範例1：

// Java program to demonstrate 
// charAt() method 
  
import java.nio.*; 
import java.util.*; 
  
public class GFG { 
    public static void main(String[] args) 
    { 
        // Creating the CharBuffer 
        try { 
  
            // creating object of CharBuffer 
            // and allocating size capacity 
            CharBuffer charbuffer 
                = CharBuffer.allocate(3); 
  
            // append the value in CharBuffer 
            // using append() method 
            charbuffer.append('a') 
                .append('b') 
                .append('c') 
                .rewind(); 
  
            // print the CharBuffer 
            System.out.println("Original CharBuffer:  "
                               + Arrays.toString( 
                                     charbuffer.array())); 
  
            // Read char at particular Index 
            // using charAt() method 
            char value = charbuffer.charAt(2); 
  
            // Display the value 
            System.out.println("\nvalue at Index 0 is:"
                               + value); 
        } 
  
        catch (IndexOutOfBoundsException e) { 
  
            System.out.println("\nindex is greater than"
                               + " the capacity minus 1"); 
            System.out.println("Exception throws:" + e); 
        } 
    } 
}

輸出：

Original CharBuffer: [a, b, c]

value at Index 0 is:c

範例2：演示IndexOutOfBoundsException。

// Java program to demonstrate 
// charAt() method 
  
import java.nio.*; 
import java.util.*; 
  
public class GFG { 
    public static void main(String[] args) 
    { 
        // Creating the CharBuffer 
        try { 
  
            // creating object of CharBuffer 
            // and allocating size capacity 
            CharBuffer charbuffer 
                = CharBuffer.allocate(3); 
  
            // append the value in CharBuffer 
            // using append() method 
            charbuffer.append('a') 
                .append('b') 
                .append('c') 
                .rewind(); 
  
            // print the CharBuffer 
            System.out.println("Original CharBuffer:  "
                               + Arrays.toString( 
                                     charbuffer.array())); 
  
            // Read char at particular Index 
            // using charAt() method 
            char value = charbuffer.charAt(3); 
  
            // Display the value 
            System.out.println("\nvalue at Index 0 is:"
                               + value); 
        } 
  
        catch (IndexOutOfBoundsException e) { 
  
            System.out.println("\nindex is greater than"
                               + " the capacity minus 1"); 
            System.out.println("Exception throws:" + e); 
        } 
    } 
}

輸出：

Original CharBuffer: [a, b, c]

index is greater than the capacity minus 1
Exception throws:java.lang.IndexOutOfBoundsException

參考： https://docs.oracle.com/javase/9/docs/api/java/nio/CharBuffer.html#charAt-int-

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注：本文由純淨天空篩選整理自RohitPrasad3大神的英文原創作品 CharBuffer charAt() methods in Java with Examples。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。