How to remove all white spaces in java [duplicate]

问题:

This question already has an answer here:

• Removing whitespace from strings in Java 30 answers

I have a programming assignment and part of it requires me to make code that reads a line from the user and removes all the white space within that line. the line can consist of one word or more.

What I was trying to do with this program is have it analyze each character until it finds a space and then save that substring as the first token. then loop again until it reaches no more tokens or the end of the line.

I keep on getting this when I try to compile it:

Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index   out of range: 1
    at java.lang.String.charAt(String.java:694)
    at trim.main(trim.java:23)

Here is the code

import java.util.Scanner ;
import java.lang.Character;
import java.lang.String ;
public class trim
{
        public static void main (String[]args)
        {

        String a  ;
        String b  ;
        String c ;
        char aChar ;
        int i = 0 ;

        Scanner scan = new Scanner(System.in);

        a = scan.nextLine();
        a =a.trim() ;


         for ( ; i >= 0 ; i++ )
         {
           aChar = a.charAt(i) ;
           if (aChar != 32)
           {
            a = a.substring(0,i+1);
           }
           else
           {
            b = a.substring(i,160) ;
            b= b.trim();
            c = c + a ;
            c = c.trim() ;
            a = b ;
            i = 0 ;
           }
           if (b.equals(null))
           {
            i = -1 ;
           }
         }
        }
}

easier ways to do this is appreciated, but I still want to get this program working.

and I can't use sentinels in the input.

---

Thanks everybody for all the help,

I will use the simpler method , and will read the javadoc.

回答1:

java.lang.String class has method substring not substr , thats the error in your program.

Moreover you can do this in one single line if you are ok in using regular expression.

a.replaceAll("\\s+","");

回答2:

Why not use a regex for this?

a = a.replaceAll("\\s","");

In the context of a regex, \s will remove anything that is a space character (including space, tab characters etc). You need to escape the backslash in Java so the regex turns into \\s. Also, since Strings are immutable it is important that you assign the return value of the regex to a.

回答3:

The most intuitive way of doing this without using literals or regular expressions:

yourString.replaceAll(" ","");

回答4:

Replace all the spaces in the String with empty character.

String lineWithoutSpaces = line.replaceAll("\\s+","");

回答5:

Try this:

String str = "Your string with     spaces";
str = str.replace(" " , "");

回答6:

Try:

  string output = YourString.replaceAll("\\s","")

s - indicates space character (tab characters etc)

回答7:

package com.infy.test;

import java.util.Scanner ;
import java.lang.String ;

public class Test1 {


    public static void main (String[]args)
    {

        String a  =null;


        Scanner scan = new Scanner(System.in);
        System.out.println("*********White Space Remover Program************\n");
        System.out.println("Enter your string\n");
    a = scan.nextLine();
        System.out.println("Input String is  :\n"+a);


        String b= a.replaceAll("\\s+","");

        System.out.println("\nOutput String is  :\n"+b);


    }
}

回答8:

public static String removeSpace(String s) {
    String withoutspaces = "";
    for (int i = 0; i < s.length(); i++) {
        if (s.charAt(i) != ' ')
            withoutspaces += s.charAt(i);

    }
    return withoutspaces;

}

This is the easiest and most straight forward method to remove spaces from a String.

回答9:

Cant you just use String.replace(" ", "");

回答10:

You can use a regular expression to delete white spaces , try that snippet:

Scanner scan = new Scanner(System.in);
    System.out.println(scan.nextLine().replaceAll(" ", ""));

回答11:

trim.java:30: cannot find symbol
symbol  : method substr(int,int)
location: class java.lang.String
b = a.substr(i,160) ;

There is no method like substr in String class.

use String.substring() method.

回答12:

String a="string with                multi spaces ";
//or this 
String b= a.replaceAll("\\s+"," ");

String c= a.replace("    "," ").replace("   "," ").replace("  "," ").replace("   "," ").replace("  "," ");

//it work fine with any spaces

*don't forget space in sting b

回答13:

boolean flag = true;
while(flag) {
    s = s.replaceAll(" ", "");
    if (!s.contains(" "))
        flag = false;
}
return s;

回答14:

String a="string with                multi spaces ";

String b= a.replace("    "," ").replace("   "," ").replace("  "," ").replace("   "," ").replace("  "," ");

//it work fine with any spaces