Removing whitespace from strings in Java

2020-01-22 11:35发布

问题:

I have a string like this:

mysz = "name=john age=13 year=2001";

I want to remove the whitespaces in the string. I tried trim() but this removes only whitespaces before and after the whole string. I also tried replaceAll("\\W", "") but then the = also gets removed.

How can I achieve a string with:

mysz2 = "name=johnage=13year=2001"

回答1:

st.replaceAll("\\s+","") removes all whitespaces and non-visible characters (e.g., tab, \n).


st.replaceAll("\\s+","") and st.replaceAll("\\s","") produce the same result.

The second regex is 20% faster than the first one, but as the number consecutive spaces increases, the first one performs better than the second one.


Assign the value to a variable, if not used directly:

st = st.replaceAll("\\s+","")


回答2:

replaceAll("\\s","")

\w = Anything that is a word character

\W = Anything that isn't a word character (including punctuation etc)

\s = Anything that is a space character (including space, tab characters etc)

\S = Anything that isn't a space character (including both letters and numbers, as well as punctuation etc)

(Edit: As pointed out, you need to escape the backslash if you want \s to reach the regex engine, resulting in \\s.)



回答3:

The most correct answer to the question is:

String mysz2 = mysz.replaceAll("\\s","");

I just adapted this code from the other answers. I'm posting it because besides being exactly what the question requested, it also demonstrates that the result is returned as a new string, the original string is not modified as some of the answers sort of imply.

(Experienced Java developers might say "of course, you can't actually modify a String", but the target audience for this question may well not know this.)



回答4:

How about replaceAll("\\s", ""). Refer here.



回答5:

One way to handle String manipulations is StringUtils from Apache commons.

String withoutWhitespace = StringUtils.deleteWhitespace(whitespaces);

You can find it here. commons-lang includes lots more and is well supported.



回答6:

If you need to remove unbreakable spaces too, you can upgrade your code like this :

st.replaceAll("[\\s|\\u00A0]+", "");


回答7:

If you prefer utility classes to regexes, there is a method trimAllWhitespace(String) in StringUtils in the Spring Framework.



回答8:

You've already got the correct answer from Gursel Koca but I believe that there's a good chance that this is not what you really want to do. How about parsing the key-values instead?

import java.util.Enumeration;
import java.util.Hashtable;

class SplitIt {
  public static void main(String args[])  {

    String person = "name=john age=13 year=2001";

    for (String p : person.split("\\s")) {
      String[] keyValue = p.split("=");
      System.out.println(keyValue[0] + " = " + keyValue[1]);
    }
  }
}

output:
name = john
age = 13
year = 2001



回答9:

You should use

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

instead of:

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

This way, it will work with more than one spaces between each string. The + sign in the above regex means "one or more \s"



回答10:

The easiest way to do this is by using the org.apache.commons.lang3.StringUtils class of commons-lang3 library such as "commons-lang3-3.1.jar" for example.

Use the static method "StringUtils.deleteWhitespace(String str)" on your input string & it will return you a string after removing all the white spaces from it. I tried your example string "name=john age=13 year=2001" & it returned me exactly the string that you wanted - "name=johnage=13year=2001". Hope this helps.



回答11:

You can do it so simply by

String newMysz = mysz.replace(" ","");


回答12:

public static void main(String[] args) {        
    String s = "name=john age=13 year=2001";
    String t = s.replaceAll(" ", "");
    System.out.println("s: " + s + ", t: " + t);
}

Output:
s: name=john age=13 year=2001, t: name=johnage=13year=2001


回答13:

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14:

\W means "non word character". The pattern for whitespace characters is \s. This is well documented in the Pattern javadoc.



回答15:

In java we can do following operation:

String pattern="[\\s]";
String replace="";
part="name=john age=13 year=2001";
Pattern p=Pattern.compile(pattern);
Matcher m=p.matcher(part);
part=m.replaceAll(replace);
System.out.println(part);

for this you need to import following packages to your program:

import java.util.regex.Matcher;
import java.util.regex.Pattern;

i hope it will help you.



回答16:

Using Pattern And Matcher it is more Dynamic.

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class RemovingSpace {

    /**
     * @param args
     * Removing Space Using Matcher
     */
    public static void main(String[] args) {
        String str= "jld fdkjg jfdg ";
        String pattern="[\\s]";
        String replace="";

        Pattern p= Pattern.compile(pattern);
        Matcher m=p.matcher(str);

        str=m.replaceAll(replace);
        System.out.println(str);    
    }
}


回答17:

Use mysz.replaceAll("\\s+","");



回答18:

mysz = mysz.replace(" ","");

First with space, second without space.

Then it is done.



回答19:

import java.util.*;
public class RemoveSpace {
    public static void main(String[] args) {
        String mysz = "name=john age=13 year=2001";
        Scanner scan = new Scanner(mysz);

        String result = "";
        while(scan.hasNext()) {
            result += scan.next();
        }
        System.out.println(result);
    }
}


回答20:

Use apache string util class is better to avoid NullPointerException

org.apache.commons.lang3.StringUtils.replace("abc def ", " ", "")

Output

abcdef


回答21:

When using st.replaceAll("\\s+","") in Kotlin, make sure you wrap "\\s+" with Regex:

"myString".replace(Regex("\\s+"), "")


回答22:

there are many ways to solve this problem. you can use split function or replace function of Strings.

for more info refer smilliar problem http://techno-terminal.blogspot.in/2015/10/how-to-remove-spaces-from-given-string.html



回答23:

To remove spaces in your example, this is another way to do it:

String mysz = "name=john age=13 year=2001";
String[] test = mysz.split(" ");
mysz = String.join("", mysz);

What this does is it converts it into an array with the spaces being the separators, and then it combines the items in the array together without the spaces.

It works pretty well and is easy to understand.



回答24:

There are others space char too exists in strings.. So space char we may need to replace from strings.

Ex: NO-BREAK SPACE, THREE-PER-EM SPACE, PUNCTUATION SPACE

Here is the list of space char http://jkorpela.fi/chars/spaces.html

So we need to modify

\u2004 us for THREE-PER-EM SPACE

s.replaceAll("[\u0020\u2004]","")



回答25:

White space can remove using isWhitespace function from Character Class.

public static void main(String[] args) {
    String withSpace = "Remove white space from line";
    StringBuilder removeSpace = new StringBuilder();

    for (int i = 0; i<withSpace.length();i++){
        if(!Character.isWhitespace(withSpace.charAt(i))){
            removeSpace=removeSpace.append(withSpace.charAt(i));
        }
    }
    System.out.println(removeSpace);
}


回答26:

Separate each group of text into its own substring and then concatenate those substrings:

public Address(String street, String city, String state, String zip ) {
    this.street = street;
    this.city = city;
    // Now checking to make sure that state has no spaces...
    int position = state.indexOf(" ");
    if(position >=0) {
        //now putting state back together if it has spaces...
        state = state.substring(0, position) + state.substring(position + 1);  
    }
}


回答27:

public static String removeWhiteSpaces(String str){
    String s = "";
    char[] arr = str.toCharArray();
    for (int i = 0; i < arr.length; i++) {
        int temp = arr[i];
        if(temp != 32 && temp != 9) { // 32 ASCII for space and 9 is for Tab
            s += arr[i];
        }
    }
    return s;
}

This might help.



回答28:

You can also take a look at the below Java code. Following codes does not use any "built-in" methods.

/**
 * Remove all characters from an alphanumeric string.
 */
public class RemoveCharFromAlphanumerics {

    public static void main(String[] args) {

        String inp = "01239Debashish123Pattn456aik";

        char[] out = inp.toCharArray();

        int totint=0;

        for (int i = 0; i < out.length; i++) {
            System.out.println(out[i] + " : " + (int) out[i]);
            if ((int) out[i] >= 65 && (int) out[i] <= 122) {
                out[i] = ' ';
            }
            else {
                totint+=1;
            }

        }

        System.out.println(String.valueOf(out));
        System.out.println(String.valueOf("Length: "+ out.length));

        for (int c=0; c<out.length; c++){

            System.out.println(out[c] + " : " + (int) out[c]);

            if ( (int) out[c] == 32) {
                System.out.println("Its Blank");
                 out[c] = '\'';
            }

        }

        System.out.println(String.valueOf(out));

        System.out.println("**********");
        System.out.println("**********");
        char[] whitespace = new char[totint];
        int t=0;
        for (int d=0; d< out.length; d++) {

            int fst =32;



            if ((int) out[d] >= 48 && (int) out[d] <=57 ) {

                System.out.println(out[d]);
                whitespace[t]= out[d];
                t+=1;

            }

        }

        System.out.println("**********");
        System.out.println("**********");

        System.out.println("The String is: " + String.valueOf(whitespace));

    }
}

Input:

String inp = "01239Debashish123Pattn456aik";

Output:

The String is: 01239123456


回答29:

private String generateAttachName(String fileName, String searchOn, String char1) {
    return fileName.replaceAll(searchOn, char1);
}


String fileName= generateAttachName("Hello My Mom","\\s","");


回答30:

Quite a lot of answers are provided. I would like to give a solution which is quite readable and better than regex.

import java.io.IOException;

import org.apache.commons.lang.StringUtils;

public class RemoveAllWhitespaceTest {

    public static void main(String[] args) throws IOException {

        String str1 = "\n\tThis is my string \n \r\n  !";

        System.out.println("[" + str1 + "]");

        System.out.println("Whitespace Removed:");

        System.out.println("[" + StringUtils.deleteWhitespace(str1) + "]");

        System.out.println();

    }

}