java - 将大写字母移至字符串末尾

Question

问题:给定一个字符串作为输入，将所有大写字母移动到字符串的末尾。示例:

move("Hello World")="ello orldHW"

问题是:我的代码没有在 ello orldHW 处停止，但它继续

ello orldHW // Expected output   
ello orldWH // What I am actually getting

代码:

public class MoveUppercaseChars {   
    static String testcase1 = "Hello World";

    public static void main(String args[]){
       MoveUppercaseChars testInstance = new MoveUppercaseChars();
       String result = testInstance.move(testcase1);
       System.out.println("Result : "+result);
    }

    public String move(String str){
       int len = str.length();
       char ch;
       for(int i=0; i<len; i++) {
          ch = str.charAt(i);
          if(((int)ch >= 65) && ((int)ch <= 90)) {
             str = str.substring(0, i) + str.substring(i+1, len) + str.charAt(i);
          }         
       }
       return str;
   }    
}

Answer 1

分别存储小写字符和大写字符，然后返回两者的串联:

public class MoveUppercaseChars {   

static String testcase1 = "Hello World";

public static void main(String args[]){
    MoveUppercaseChars testInstance = new MoveUppercaseChars();
    String result = testInstance.move(testcase1);
    System.out.println("Result : "+result);
}

public String move(String str){
    int len = str.length();
    String low = "";
    String cap = "";
    char ch;
    for(int i=0; i<len; i++)
    {
        ch = str.charAt(i);
        if(((int)ch >= 65) && ((int)ch <= 90))
        {
            cap  += ch;
        }   
        else {
            low += ch;
        }
    }
    return low + cap;
}   
}