How to use the substring() function of the StringBuilder class in Java to intercept the substring of a string

How does Java use the substring() function of the StringBuilder class to intercept the substring of a string

In Java, we often need to process string operations. Java's StringBuilder class provides a series of methods to facilitate us to operate strings. Among them, the substring() function can be used to intercept substrings of strings.

The substring() function has two overloaded forms, namely substring(int startIndex) and substring(int startIndex, int endIndex). The following code examples will illustrate how to use these two forms to intercept substrings of strings.

1. Use the substring(int startIndex) function to intercept the substring of the string

When using the substring(int startIndex) function to intercept the substring of the string, the startIndex parameter represents the substring The starting position of the string. The value range is from 0 to the length of the string minus 1.

The following is a sample code:

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

        // 截取从索引位置5开始到字符串末尾的子串
        String sub = sb.substring(5);

        System.out.println(sub);
    }
}

In the above code, we create a StringBuilder object sb and pass the string "Hello, World!" into the constructor for initialization. Then, we call the substring() function and pass in the starting position 5, that is, intercept the substring starting from index position 5. Finally, by printing the output, we can see that the result is "World!", that is, the substring from index position 5 to the end of the string is intercepted.

2. Use the substring(int startIndex, int endIndex) function to intercept the substring of the string

Use the substring(int startIndex, int endIndex) function to intercept the substring of the string When , the startIndex parameter indicates the starting position of the substring, and the endIndex parameter indicates the end position of the substring. The value range is from 0 to the length of the string minus 1.

The following is a sample code:

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

        // 截取从索引位置0开始，到索引位置5之前的子串
        String sub = sb.substring(0, 5);

        System.out.println(sub);
    }
}

In the above code, we also created a StringBuilder object sb and passed the string "Hello, World!" into the constructor for initialization . Then, we call the substring() function and pass in the starting position 0 and the ending position 5, that is, the substring from index position 0 to index position 5 is intercepted. Finally, by printing the output, we can see that the result is "Hello", that is, the required substring has been intercepted.

Summary

Through the above example code, we can see that it is very simple to use the substring() function of the StringBuilder class in Java to intercept the substring of a string. Whether it is to intercept the substring from the specified position to the end, or to intercept the substring within the specified range, it can be achieved by calling the substring() function. By flexibly using these functions, we can operate and process strings more conveniently.

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