[Java知识库]将字符串中连续的多个空格替换成一个空格

方式一

public static void main(String[] args) {
        String str = "   abc            def       ghi    mnopq      r       s ";
        StringTokenizer pas = new StringTokenizer(str, " ");

        str = ""; 

        while (pas.hasMoreTokens()) {
            String s = pas.nextToken();
            str = str + s + " ";
        }
        System.out.println("[" + str.trim() + "]");
    }

[abc def ghi rrr r s]

方式二

    public static void main(String[] args) {
        String str = "      h         r l   h     .      ";
        System.out.println("str =[" + str + "]");
        String newStr = str.replaceAll(" + ", " ");
        System.out.println("newStr ——[" + newStr.trim() + "]");
    }

str =[h         r l   h     .]
newStr ——[h r l h .]

方式三

    public static void main(String[] args) {
        String str = "      h         r l   h     .      ";
        System.out.println("str =[" + str + "]");
        String newStr = repaceWhiteSapce(str);
        System.out.println("newStr ——[" + newStr.trim() + "]");



    }

    public static String repaceWhiteSapce(String original) {
        StringBuilder sb = new StringBuilder();
        boolean isFirstSpace = false;//标记是否是第一个空格

        original = original.trim();//如果考虑开头和结尾有空格的情形

        char c;
        for (int i = 0; i < original.length(); i++) {
            c = original.charAt(i);
            if (c == ' ' || c == '\t') {//遇到空格字符时,先判断是不是第一个空格字符
                if (!isFirstSpace) {
                    sb.append(c);
                    isFirstSpace = true;
                }
            } else {//遇到非空格字符时
                sb.append(c);
                isFirstSpace = false;
            }
        }
        return sb.toString();
    }

str =[      h         r l   h     .      ]
newStr ——[h r l h .]