Java uses the insert() function of the StringBuilder class to insert content into a string

Java uses the insert() function of the StringBuilder class to insert content into a string

The StringBuilder class in Java is a variable string class that provides a wealth of methods to operate strings. The insert() function can insert specified content into a string, which is very flexible and practical.

Using the insert() function of the StringBuilder class, you can insert the specified content into the specified position of the string. The following is a simple example:

public class StringBuilderExample {

    public static void main(String[] args) {
        StringBuilder sb = new StringBuilder("Hello, world!");

        // 在字符串的索引位置5插入字符'，'
        sb.insert(5, ',');

        // 在字符串的索引位置7插入字符串"Java"
        sb.insert(7, "Java");

        // 在字符串的末尾插入字符串"!"
        sb.insert(sb.length(), "!");

        // 输出结果
        System.out.println(sb.toString());  // 输出: Hello, Java, world!!
    }
}

In the above code, first create a StringBuilder object and initialize the string "Hello, world!". Then use the insert() function to insert content at the specified position in the string as required. Finally, use the toString() function to convert the StringBuilder object to a string and output the result.

In the example, the first insert() function inserts the comma character ',' into the string index position 5, and the resulting string becomes "Hello, world!". The second insert() function inserts the string "Java" at index position 7, and the result is "Hello, Java, world!". The last insert() function inserts the exclamation mark character '!' to the end of the string, and the result is "Hello, Java, world!!".

By using the insert() function, we can insert content into any position of the string at will, thereby flexibly operating and processing the string.

It should be noted that the StringBuilder class is mutable, which means that we can modify the original string without creating a new string object, which can reduce memory overhead. . In addition, the methods of the StringBuilder class are not thread-safe. If used in a multi-threaded environment, the StringBuffer class should be used. Its methods are all thread-safe.

In short, using the insert() function of the StringBuilder class in Java can insert content into a string, providing a flexible and efficient way to process strings. Mastering this method can facilitate string manipulation and processing, which is very useful in actual development.

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