java charAt（）方法和代理

Question

I am writing java code and want to know why the output of this code is x . I was expecting t since it is the 5th letter.

public class StringBufferDemo{
    public static void main(String args[]){
        StringBuffer sb = new StringBuffer("ttsttxctlltnt");
        System.out.println(sb.charAt(5));
    }
}

Answer 1

It's because in java a StringBuffer object is indexed starting at 0. 1 ^st char at position 0, 2 ^nd char at position 1, etc...

String ------ "t t s t t x c t l l"
ArrayIndex --  0 1 2 3 4 5 6 7 8 9

Answer 2

索引从0开始而不是1。因此，在字符串“ ttsttxctlltnt”中，将打印位置5（0,1,2,3,4,5）处的字符，即“ x”。

Answer 3

索引从0开始，所以第5个字符的字符是x ...如果您想将t作为输出，请尝试以下操作

 System.out.println(sb.charAt(4));