Use java's StringBuilder.lastIndexOf() function to find the last position of a substring in the string buffer

Use Java's StringBuilder.lastIndexOf() function to find the last position of a substring in the string buffer

In Java, strings are immutable, which means that once a character is created String object, its value cannot be changed. In some cases, we may need to modify strings frequently. To solve this problem, Java provides the variable string class StringBuilder.

The StringBuilder class is a class under the Java.lang package. It provides many methods to operate strings. One of them is the lastIndexOf() function, which is used to find the last occurrence of a substring in a string buffer.

The following is a sample code using the StringBuilder.lastIndexOf() function:

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

        // 使用lastIndexOf()函数查找字符'o'在字符串中的最后位置
        int lastIndex = strBuilder.lastIndexOf("o");

        // 输出结果
        System.out.println("最后位置索引: " + lastIndex);
    }
}

In the above example, we create a StringBuilder object and initialize its value to "Hello World! ". Then, we use the lastIndexOf() function to find the last position of the character 'o' in the string.

Run the above code, the output result is:

最后位置索引: 7

As can be seen from the output result, the last position index of the character 'o' in the string is 7.

It should be noted that the lastIndexOf() function returns the index position of the last matching substring. If no matching substring is found, it returns -1. In the above example, since there is a character 'o' in the string, the function returns the index position of the last occurrence of the character 'o'.

In addition to finding a single character, the lastIndexOf() function can also be used to find the last position of a substring. The following is a sample code that uses the StringBuilder.lastIndexOf() function to find substrings:

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

        // 使用lastIndexOf()函数查找子字符串"World"在字符串中的最后位置
        int lastIndex = strBuilder.lastIndexOf("World");

        // 输出结果
        System.out.println("子字符串最后位置索引: " + lastIndex);
    }
}

Run the above code, the output result is:

子字符串最后位置索引: 6

As can be seen from the output result, the subcharacter The last position index of the string "World" in the string is 6.

To summarize, you can easily find the last position of a substring in the string buffer using the lastIndexOf() function in Java's StringBuilder class. Whether looking for a single character or a substring, this function serves our needs well.

The above is the detailed content of Use java's StringBuilder.lastIndexOf() function to find the last position of a substring in the string buffer. For more information, please follow other related articles on the PHP Chinese website!