java - Java替换字符串特定位置的字符？

Question

我正在尝试替换字符串特定位置的字符。

例如：

String str = "hi";

将字符串位置 #2 (i) 替换为另一个字母“k”

我该怎么做？谢谢！

Answer 1

Petar Ivanov的答案以替换字符串问题中特定索引处的字符

字符串在 Java 中是不可变的。你不能改变它们。

您需要创建一个替换字符的新字符串。

String myName = "domanokz";
String newName = myName.substring(0,4)+'x'+myName.substring(5);

或者您可以使用 StringBuilder：

StringBuilder myName = new StringBuilder("domanokz");
myName.setCharAt(4, 'x');

System.out.println(myName);

Answer 2

Kay!

First of all, when dealing with strings you have to refer to their positions in 0 base convention. This means that if you have a string like this:

String str = "hi";
//str length is equal 2 but the character
//'h' is in the position 0 and character 'i' is in the postion 1

With that in mind, the best way to tackle this problem is creating a method to replace a character at a given position in a string like this:

Method:

public String changeCharInPosition(int position, char ch, String str){
    char[] charArray = str.toCharArray();
    charArray[position] = ch;
    return new String(charArray);
}

Then you should call the method 'changeCharInPosition' in this way:

String str = "hi";
str = changeCharInPosition(1, 'k', str);
System.out.print(str); //this will return "hk"

If you have any questions, don't hesitate, post something!

Answer 3

使用StringBuilder：

StringBuilder sb = new StringBuilder(str);
sb.setCharAt(i - 1, 'k');
str = sb.toString();

Answer 4

替换指定位置的字符：

public static String replaceCharAt(String s, int pos, char c) {
   return s.substring(0,pos) + c + s.substring(pos+1);
}

Answer 5

如果您需要重用字符串，请使用StringBuffer：

String str = "hi";
StringBuffer sb = new StringBuffer(str);
while (...) {
    sb.setCharAt(1, 'k');
}

编辑：

请注意，StringBuffer是线程安全的，而使用StringBuilder更快，但不是线程安全的。