How to replace all occurrences in a string using replaceAll() function of String class in Java

JavaHow to replace all matches in a string using the replaceAll() function of the String class

In Java, the String class provides many convenient methods to process strings. One of them is the replaceAll() function, which allows us to replace all matches in a string by specifying a regular expression. This article will introduce how to use the replaceAll() function to achieve this function and provide corresponding code examples.

The syntax of the replaceAll() function is as follows:

public String replaceAll(String regex, String replacement)

Where, regex is the regular expression to be matched, and replacement is the string used to replace the matched item.

The following are the basic steps to use the replaceAll() function to replace all matches in a string:

1. Create a String object and assign it to the string that needs to be replaced.
2. Use the replaceAll() function and specify the regular expression and replacement string to match. Return the replaced result to a new String object.
3. Use a new String object to access the replaced string.

The following is a sample code that demonstrates how to use the replaceAll() function to replace all matches in a string:

public class ReplaceExample {

    public static void main(String[] args) {
        String str = "Hello Java, Java is a programming language";
        String replacedStr = str.replaceAll("Java", "Python");
        System.out.println("替换前的字符串：" + str);
        System.out.println("替换后的字符串：" + replacedStr);
    }
}

Output result:

替换前的字符串：Hello Java, Java is a programming language
替换后的字符串：Hello Python, Python is a programming language

In In the above code, we first create a string str and assign it the value "Hello Java, Java is a programming language". Then, we use the replaceAll() function to replace all "Java" with "Python" and assign the result to the replacedStr string. Finally, we print out the string before and after replacement.

It should be noted that the replaceAll() function uses regular expressions for matching. Therefore, when specifying regex parameters, we can use various syntaxes of regular expressions to flexibly match different strings. For example, we can use replaceAll("[Jj]ava", "Python") to replace the case-insensitive "Java" with "Python".

Summary:
This article introduces how to use the replaceAll() function of the String class to replace all matches in a string. We can achieve this function by specifying regular expressions and replacement strings. With this simple example code, you can easily learn and master this useful function.

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