//判断是否char是否为空
import java.util.*;

public class test{

 public static void main(String[] args){

 String str="abc abc";

 char [] ch=str.toCharArray();

 for(int i=;i<ch.length;i++) {

     if(Character.isSpace(ch[i]))  System.out.println("ok");

}

  }

 }

  //判断char是否为空字符串         
  char M='A';

            if(M!='\0')

                System.out.println("字符M不为空");

            char[] N=new char[];

            if(N[]=='\0')

                System.out.println("字符N[0]为空\n\n\n\n");