Java 中的 CharBuffer charAt()方法，示例
原文:https://www . geesforgeks . org/char buffer-charat-methods-in-Java-with-examples/
Java . nio . charbuffer类的 charAt() 方法用于读取相对于当前位置的给定索引处的字符。
语法:
public final char charAt(int index)
参数:该方法取待读字符相对于位置的索引；必须是非负的，并且小于剩余的()。
返回值:该方法返回索引位置()+索引处的字符。
异常:如果索引上的前提条件不成立，该方法抛出indexout of boundsexception。
下面是说明 charAt(int index)方法的例子:
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);
}
}
}
输出:
Original CharBuffer: [a, b, c]
value at Index 0 is : c
示例 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);
}
}
}
输出:
Original CharBuffer: [a, b, c]
index is greater than the capacity minus 1
Exception throws : java.lang.IndexOutOfBoundsException
参考:https://docs . Oracle . com/javase/9/docs/API/Java/nio/charbuffer . html # charAt-int-
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