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在Java中的字符串中的所有字母之前和之后插入一个字符

发布于 2025-01-07 00:23:08 字数 128 浏览 0 评论 0原文

我想在字符串中的每个字母之后插入一个 % 字符，但使用 StringBuilder 来加快速度。

例如，如果字符串是“AA”，那么它将是“%A%A%”。如果是 'XYZ' 那么它将是 '%X%Y%Z%'

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瀟灑尐姊 2025-01-14 00:23:08

String foo = "VWXYZ";
foo = "%" + foo.replaceAll("(.)","$1%");
System.out.println(foo);

输出：

%V%W%X%Y%Z%

您不需要 StringBuilder。编译器将通过使用一个来为您处理正则表达式之前的简单串联。

编辑以响应以下评论：

replaceAll() 使用正则表达式（regex）。

正则表达式 (.) 表示“匹配任何字符，并给我一个对它的引用” . 是任何字符的通配符，括号创建反向引用。第二个参数中的 $1 表示“使用匹配中的反向引用 #1”。

replaceAll() 在整个字符串上不断运行此表达式，将每个字符替换为自身后跟百分号，构建一个新字符串，然后将其返回给您。

String foo = "VWXYZ";
foo = "%" + foo.replaceAll("(.)","$1%");
System.out.println(foo);

Output:

%V%W%X%Y%Z%

You don't need a StringBuilder. The compiler will take care of that simple concatenation prior to the regex for you by using one.

Edit in response to comment below:

replaceAll() uses a Regular Expression (regex).

The regex (.) says "match any character, and give me a reference to it" . is a wildcard for any character, the parenthesis create the backreference. The $1 in the second argument says "Use backreference #1 from the match".

replaceAll() keeps running this expression over the whole string replacing each character with itself followed by a percent sign, building a new String which it then returns to you.

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笑梦风尘 2025-01-14 00:23:08

尝试这样的事情：

    String test = "ABC";
    StringBuilder builder = new StringBuilder("");
    builder.append("%");
    for (char achar : test.toCharArray()) {
        builder.append(achar);
        builder.append("%");
    }
    System.out.println(builder.toString());

Try something like this:

    String test = "ABC";
    StringBuilder builder = new StringBuilder("");
    builder.append("%");
    for (char achar : test.toCharArray()) {
        builder.append(achar);
        builder.append("%");
    }
    System.out.println(builder.toString());

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情绪失控 2025-01-14 00:23:08

public static String escape(String s) {
    StringBuilder buf = new StringBuilder();
    boolean wasLetter = false;
    for (char c: s.toCharArray()) {
        boolean isLetter = Character.isLetter(c);
        if (isLetter && !wasLetter) {
            buf.append('%');
        }
        buf.append(c);
        if (isLetter) {
            buf.append('%');
        }
        wasLetter = isLetter;
    }
    return buf.toString();
}

public static String escape(String s) {
    StringBuilder buf = new StringBuilder();
    boolean wasLetter = false;
    for (char c: s.toCharArray()) {
        boolean isLetter = Character.isLetter(c);
        if (isLetter && !wasLetter) {
            buf.append('%');
        }
        buf.append(c);
        if (isLetter) {
            buf.append('%');
        }
        wasLetter = isLetter;
    }
    return buf.toString();
}

回复收藏 0 原文

感情旳空白 2025-01-14 00:23:08

StringBuilder sb = new StringBuilder("AAAAAAA");

for(int i = sb.length(); i >= 0; i--)
{
    sb.insert(i, '%');
}

StringBuilder sb = new StringBuilder("AAAAAAA");

for(int i = sb.length(); i >= 0; i--)
{
    sb.insert(i, '%');
}

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流殇 2025-01-14 00:23:08

你可能会看到这个。

    String s="AAAA";
    StringBuilder builder = new StringBuilder();
    char[] ch=s.toCharArray();
    for(int i=0;i<ch.length;i++)
    {
        builder.append("%"+ch[i]);
    }
    builder.append("%");
    System.out.println(builder.toString());

输出

    %A%A%A%A%

You may see this.

    String s="AAAA";
    StringBuilder builder = new StringBuilder();
    char[] ch=s.toCharArray();
    for(int i=0;i<ch.length;i++)
    {
        builder.append("%"+ch[i]);
    }
    builder.append("%");
    System.out.println(builder.toString());

Output

    %A%A%A%A%

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梦里南柯 2025-01-14 00:23:08

我同意 @Brian Roach 在前后添加字符，但如果您想添加任何特定字符，请执行以下操作像这样

String source = "hello good old world";
StringBuffer res = new StringBuffer();
String[] strArr = tagList.split(" ");

for (String str : strArr) {
     char[] stringArray = str.trim().toCharArray();
     stringArray[0] = stringArray[0];
     str = new String(stringArray);
     //here you need to specify your first and last character which you want to set 
     res.append("#"+ str + "$").append(" ");
 }

 System.out.println("Result: " + res.toString().trim());

输出：- #hello$ #good$ #old$ #world$

I agree with @Brian Roach to add character to before and after but if you want to add any specific character then do like this

String source = "hello good old world";
StringBuffer res = new StringBuffer();
String[] strArr = tagList.split(" ");

for (String str : strArr) {
     char[] stringArray = str.trim().toCharArray();
     stringArray[0] = stringArray[0];
     str = new String(stringArray);
     //here you need to specify your first and last character which you want to set 
     res.append("#"+ str + "$").append(" ");
 }

 System.out.println("Result: " + res.toString().trim());