如何用java语言编写“求一个字符串中的的字母，数字，空格的数目。”

方法一：

public class StringNumber { private String str=" "; private int z=0; private int k=0; private int g=0; public StringNumber(String str){  this.str=str; } public void strNumber(){  byte buf[]=str.getBytes();    for(int i=0;i<str.length();i++){   if(buf[i]==' '){    z++;   }   if((buf[i]>='0')&&(buf[i]<='9')){    k++;   }   if(((buf[i]>='a')&&(buf[i]<='z'))||((buf[i]>='A')&&(buf[i]<='Z'))){    g++;   }  }      System.out.println("空格数是"+z);  System.out.println("数字个数"+k);  System.out.println("字母个数"+g);       }   public static void main(String[] args) {  // TODO: 在这添加你的代码   StringNumber strnumber = new StringNumber("aaasdfdsfdsf  fdAADD3432 erew34");    strnumber.strNumber();   }}方法二：
public class Test{ public static void main(String[] args)  {  int space = 0, number = 0, character = 0;  String str = "23 ffa 4fasd";  for (int i = 0; i < str.length(); i++)   {   char ch = str.charAt(i);      if (ch == ' ')      {          space++;      }   if ((ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z'))   {       character++;   }   if (ch >= '0' && ch <= '9')    {       number++;   }  }  System.out.println("number: " + number);  System.out.println("character: " + character);  System.out.println("space: " + space); }}