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

有许多方法可以解决这个问题。您可以使用拆分函数或替换字符串的函数。

有关更多信息，请参阅微笑问题http://techno-terminal.blogspot.in/2015/10/how-to-remove-spaces-from-given-string.html

您需要的代码是

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

这将删除所有空白。

最简单的方法是使用commons-lang3库的org.apachemons.lang3.StringUtils类，例如“commons-lang3-3.1.jar”。

对输入字符串使用静态方法“StringUtils.deleteWhitespace（Stringstr）”&它将在删除所有空格后返回一个字符串。我尝试了示例字符串“name=johnage=13year=2001”&它返回了您想要的字符串-“name=johnage=13yeal=2001”。希望这有帮助。

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

将每组文本分隔成自己的子字符串，然后连接这些子字符串：

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);  
    }
}