Inverting strings can be implemented in Java in a variety of ways. 1. It is most recommended to use the reverse() method of StringBuilder. The code is simple and efficient: new StringBuilder(original).reverse().toString(); 2. You can manually traverse the character array and exchange characters to achieve inversion, which helps you understand the underlying logic; 3. You can also use the Java 8 Stream API to achieve functional style inversion, but the performance and readability are poor, which is only suitable for practice. The StringBuilder method is the first choice in actual development, and other methods can be selected and used according to specific needs.
Reversing a string is a common operation in Java, especially in interview questions or basic exercises. Although Java does not provide direct inversion methods for String classes, it can be easily implemented with some simple means.
Using StringBuilder
The easiest and most recommended way is to use StringBuilder , which comes with reverse() method:
String original = "hello"; String reversed = new StringBuilder(original).reverse().toString();
This method has a simple code, is readable and is also very efficient. Suitable for most daily development scenarios.
Manually traverse character array
If you can't use StringBuilder (such as in some restricted environments), or want to implement it manually to deepen your understanding, you can traverse the character array from behind to front:
public static String reverseString(String str) {
char[] chars = str.toCharArray();
int left = 0;
int right = chars.length - 1;
while (left < right) {
// Exchange the characters on the left and right sides char temp = chars[left];
chars[left] = chars[right];
chars[right] = temp;
left ;
right--;
}
return new String(chars);
}The advantage of this approach is that it can see the inversion process more clearly. You can also change it to recursion, but recursion is generally not recommended because it is easy to overflow.
Streams using Java 8
If you like functional style, you can also use the Stream API to implement string inversion:
String original = "hello";
String reversed = original.chars()
.mapToObj(c -> (char) c)
.sorted((a, b) -> b.compareTo(a))
.collect(StringBuilder::new, StringBuilder::append, StringBuilder::append)
.toString();Note: Although this method looks "advanced", it is not actually designed to reverse the design, and its performance and readability are not as good as the first two. It is only suitable for practicing or showing ideas, and is not recommended in actual development.
Basically these commonly used methods. Among them, StringBuilder.reverse() is the most practical, and manual implementation helps to understand the underlying logic. Just choose the right method according to different needs.
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