JAVA中toCharArray()的用法

发表于
toCharArray()很实用很灵活哦

toCharArray()的用途

将字符串对象中的字符串转换为一个字符数组

simple example

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String myString="abcd";
char myChar[]=myString.toCharArray();
System.out.println("myChar[1]="+myChar[1]);

输出结果：
myChar[1]=b

Attention

让我们简单地看一下这个例子

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String str="hello";
char c[]={'h','e','l','l','o'};
char ch[]=str.toCharArray();
if(ch.equals(c))
System.out.println("true");
else
System.out.println("false");

这个例子的输出结果是false:因为数组是对象，数组没有重写equals方法，默认还是比较的内存地址，你是两个不同的数组，地址当然不一样了！
你可以用Java.util.Arrays.equals(ch,c);进行比较
c和ch是不同的对象数组，虽然数组里面的值是一样的，但是他们的存储地址并不一样。按你的程序来，运行结果是false是正确的。
数组是对象不是基本变量，不可以这样比较的。因为存储地址不一样。字符数组以/0结尾

exercise

HDOJ<1020>-Encoding Problem
request
Given a string containing only ‘A’ - ‘Z’, we could encode it using the following method:

  1. Each sub-string containing k same characters should be encoded to “kX” where “X” is the only character in this sub-string.
  2. If the length of the sub-string is 1, ‘1’ should be ignored.

    Input

    The first line contains an integer N (1 <= N <= 100) which indicates the number of test cases.
    The next N lines contain N strings. Each string consists of only ‘A’ - ‘Z’ and the length is less than 10000.

    Output

    For each test case, output the encoded string in a line.

    Sample Input

    2
    ABC
    ABBCCC

    Sample Output

    ABC
    A2B3C

    answer

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    import java.util.Scanner;
    public class Main
    {
        public static void main(String agrs[])
        {
            Scanner read = new Scanner (System.in);
            int n = read.nextInt();
            read.nextLine();
            while(n--!=0)//跳出循环条件
            {
                String str = read.nextLine();
                char get[]= str.toCharArray();//转换成字符数组
                String put="";
                for(int i=1,count=1;i<=str.length();i++)
                {
                    if(i==str.length())
                    {
                        if(count!=1)
                            put+=count;
                        put+=get[i-1];
                        break;//跳出循环条件
                    }
                    if(get[i]==get[i-1])
                        count++;
                    else
                    {
                        if(count!=1)
                            put+=count;
                        put+=get[i-1];
                        count=1;
                    }
                }
                System.out.println(put);
            }
        }
    }