The value of the String class value the role of the judge for anempty String

String how such a judgment is empty . .
because after all, s = ""

And value may also have more than one value as



json just my name from the program to the here and json irrelevant.
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s.equals (""); and s.isEmpty (); same bar that this is not acceptable then count = 1      

    

    Since the count is 1
    
not necessarily that which is really empty , but there may be an unknown special characters ,     
At least you got to come out of this s how to tell about it , or how to know whether it is empty inside it . .    

  

  
  
  

				StringBuilder sb = new StringBuilder();
 				for (String s = reader.readLine(); s != null; s = reader
 						.readLine())
 				{
 					sb.append(s);
 				}

  
  
read a completely empty pages  

really do not know how it comes out . .

 public static void main(String[] args) throws Exception {
 		FileReader fr=new FileReader(new File("D:\\tttt.html"));
 		BufferedReader reader=new BufferedReader(fr);
 		StringBuilder sb = new StringBuilder();
 //这个for循环根本就没有执行。。
 		for (String s = reader.readLine(); s != null; s = reader.readLine())
 		{
 		    sb.append(s);
 		}
 		System.out.println(sb.toString());
 	}

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s.equals ("");
This trip
empty string and null is not a concept . .

Question 2 which together no matter how many empty after should still be a blank. .
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using tools like apache bar
org.apache.commons.lang.StringUtils
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value seemingly breakpoint view values ​​to see is something like an array

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s.equals (""); and s.isEmpty (); same bar that this is not acceptable count = 1 it
------ For reference only - -------------------------------------

  
s.equals (""); and s.isEmpty (); same bar that this is not acceptable then count = 1  

Since the count is 1

not necessarily that which is really empty , but there may be an unknown special characters ,
At least you got to come out of this s how to tell about it , or how to know whether it is empty inside it . .
------ For reference only -------------------------------------- -

    
s.equals (""); and s.isEmpty (); same bar that this is not acceptable then count = 1    

  

  Since the count is 1
  
not necessarily that which is really empty , but there may be an unknown special characters ,   
At least you got to come out of this s how to tell about it , or how to know whether it is empty inside it . .  

				StringBuilder sb = new StringBuilder();
 				for (String s = reader.readLine(); s != null; s = reader
 						.readLine())
 				{
 					sb.append(s);
 				}

read a completely empty pages
------ For reference only --------------------------- ------------

  
s.equals (""); and s.isEmpty (); same bar that this is not acceptable then count = 1  

general we are such judgments :
null! = s && "". equals (s)

s.isEmpty (), accidentally ran null