java 增加字符串值

Increase string value

提问by hogni89

Java question here: If i have a string "a", how can I "add" value to the string, so I get a "b" and so on? like "a++"

这里的 Java 问题：如果我有一个字符串“a”，我如何向字符串“添加”值，所以我得到一个“b”等等？像“a++”

回答by Jigar Joshi

String str = "abcde";
System.out.println(getIncrementedString(str));

Output

输出

bcdef

定义

//this code will give next char in unicode sequence

//此代码将给出unicode序列中的下一个字符

public static String getIncrementedString(String str){
        StringBuilder sb = new StringBuilder();
        for(char c:str.toCharArray()){
            sb.append(++c);
        }
        return sb.toString();
    }

回答by Mark

If you use the char primitive data type you can accomplish this:

如果您使用 char 原始数据类型，您可以完成此操作：

char letter = 'a';
letter++;
System.out.println(letter);

prints out b

打印出 b

回答by Israel Dominguez

i made some changes to te paulo eberman code, to handle digits and characters, if valuable for someone i share this mod....

我对 te paulo eberman 代码进行了一些更改，以处理数字和字符，如果对我共享此 mod 的人有价值....

public final static char MIN_DIGIT = '0';
public final static char MAX_DIGIT = '9';
public final static char MIN_LETTER = 'A';
public final static char MAX_LETTER = 'Z';

public String incrementedAlpha(String original) {
    StringBuilder buf = new StringBuilder(original);
    //int index = buf.length() -1;
    int i = buf.length() - 1;
    //while(index >= 0) {
    while (i >= 0) {
        char c = buf.charAt(i);
        c++;
        // revisar si es numero
        if ((c - 1) >= MIN_LETTER && (c - 1) <= MAX_LETTER) {
            if (c > MAX_LETTER) { // overflow, carry one
                buf.setCharAt(i, MIN_LETTER);
                i--;
                continue;
            }

        } else {
            if (c > MAX_DIGIT) { // overflow, carry one
                buf.setCharAt(i, MIN_DIGIT);
                i--;
                continue;
            }
        }
        // revisar si es numero
        buf.setCharAt(i, c);
        return buf.toString();
    }
    // overflow at the first "digit", need to add one more digit
    buf.insert(0, MIN_DIGIT);
    return buf.toString();
}

i hope be usefull for someone.

我希望对某人有用。

回答by tvshajeer

use this code to increment char value by an integer

使用此代码将 char 值增加一个整数

int a='a';
System.out.println("int: "+a);
a=a+3;
char c=(char)a;
System.out.println("char :"+c);

回答by dogbane

• Convert the string to a char.
• Increment the char.
• Convert the char back to a string.

• 将字符串转换为字符。
• 增加字符。
• 将字符转换回字符串。

Example:

例子：

    //convert a single letter string to char
    String a = "a";
    char tmp = a.charAt(0);

    //increment char
    tmp++;

    //convert char to string
    String b = String.valueOf(tmp);
    System.out.println(b);

回答by Pa?lo Ebermann

Assuming you want something like aaab=> aaacand not => bbbc, this would work:

假设您想要类似aaab=>aaac而不是 => 的东西bbbc，这将起作用：

public String incremented(String original) {
    StringBuilder buf = new StringBuilder(original);
    int index = buf.length() -1;
    while(index >= 0) {
       char c = buf.charAt(i);
       c++;
       buf.setCharAt(i, c);
       if(c == 0) { // overflow, carry one
          i--;
          continue;
       }
       return buf.toString();
    }
    // overflow at the first "digit", need to add one more digit
    buf.insert(0, '');
    return buf.toString();
}

This treats all characters (in fact charvalues) the same, and fails (does strange stuff) for some unicode code-points outside the first plane (which occupy two char values in a String).

这将所有字符（实际上是char值）视为相同，并且对于第一个平面（在字符串中占据两个字符值）之外的某些 unicode 代码点失败（做奇怪的事情）。

If you only want to use english lowercase lettersas digits, you can try this variant:

如果你只想使用英文小写字母作为数字，你可以试试这个变体：

public final static char MIN_DIGIT = 'a';
public final static char MAX_DIGIT = 'z';

public String incrementedAlpha(String original) {
    StringBuilder buf = new StringBuilder(original);
    int index = buf.length() -1;
    while(index >= 0) {
       char c = buf.charAt(i);
       c++;
       if(c > MAX_DIGIT) { // overflow, carry one
          buf.setCharAt(i, MIN_DIGIT);
          i--;
          continue;
       }
       buf.setCharAt(i, c);
       return buf.toString();
    }
    // overflow at the first "digit", need to add one more digit
    buf.insert(0, MIN_DIGIT);
    return buf.toString();
}

This does a=> b=> c, y=> z=> aa=> ab.

这确实a=> b=> c，y=> z=> aa=> ab。

if you want to do more calculation with the string, consider staying with StringBuilder (or StringBuffer for multithreaded access) instead of repeatedly copying between String and StringBuilder. Or use a class made to do this, like BigInteger.

如果您想对字符串进行更多计算，请考虑使用 StringBuilder（或用于多线程访问的 StringBuffer），而不是在 String 和 StringBuilder 之间重复复制。或者使用一个类来做到这一点，比如 BigInteger。