如果您更喜欢实用程序类而不是正则表达式，那么Spring Framework中的StringUtils中有一个方法trimAllWhitespace（String）。

您可以在不使用replaceAll（）或Java中的任何预定义方法的情况下实现这一点。这种方式是优选的：-

public class RemoveSpacesFromString {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        String newString;
        String str = "prashant is good" ;
        int i;
        char[] strArray = str.toCharArray();
        StringBuffer sb =  new StringBuffer();
        
        for(i = 0; i < strArray.length; i++)
        {
            if(strArray[i] != ' ' && strArray[i] != '\t')
            {
                sb.append(strArray[i]);
            }
        }
        System.out.println(sb);
    }
}

您还可以查看下面的Java代码。以下代码不使用任何“内置”方法。

/**
 * 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));

    }
}

输入：

String inp = "01239Debashish123Pattn456aik";

输出：

The String is: 01239123456

\W表示“非文字字符”。空白字符的模式为%s。这在Pattern javadoc中有很好的记录。

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

//任何空间都可以使用*别忘了sting b中的空格

如果要删除字符串中的所有空格：

public String removeSpace(String str) {
    String result = "";
    for (int i = 0; i < str.length(); i++){
        char c = str.charAt(i);        
        if(c!=' ') {
            result += c;
        }
    }
    return result;
}