Use Java's String.replace() function to replace characters (strings) in a string

Use Java's String.replace() function to replace characters (strings) in a string

In Java, strings are immutable objects, which means that once a string object is created, Its value cannot be modified. However, you may encounter situations where you need to replace certain characters or strings in a string. At this time, we can use the replace() method in Java's String class to implement string replacement.

The replace() method of the String class has two overloaded forms:

1. replace(char oldChar, char newChar): Replace all occurrences in the string with the specified new character of specified old characters.
2. replace(CharSequence target, CharSequence replacement): Replace all occurrences of the specified old string in the string with the specified new string.

Here are some examples of using the String.replace() function:

Example 1: Replace a character

String str = "Hello World";
String newStr = str.replace('o', 'X');
System.out.println(newStr);  // 输出：HellX WXrld

In the above example, we replaced All characters 'o' in the string "Hello World" are 'X'.

Example 2: Replace a string

String str = "Hello Java!";
String newStr = str.replace("Java", "World");
System.out.println(newStr);  // 输出：Hello World!

In the above example, we replaced the substring "Java" in the string "Hello Java!" with "World".

It should be noted that the String.replace() function returns a new string object, and the original string will not be modified. Therefore, you need to assign the returned new string to a new variable or overwrite the original string.

Example 3: Replace multiple characters in a string

String str = "Hello World";
String newStr = str.replace("o", "X").replace("W", "!");
System.out.println(newStr);  // 输出：HellX !xrld

In the above example, we continuously call the replace() function to replace multiple characters in the string.

Example 4: Replace string using regular expression

String str = "Hello123Java456!";
String newStr = str.replaceAll("[0-9]", "");
System.out.println(newStr);  // 输出：HelloJava!

In the above example, we use the regular expression "[0-9]" to match the numbers in the string, and Replace matching numbers with an empty string.

Summary:
String.replace() function is an important function in Java for replacing characters (strings) in strings. It can modify strings quickly and easily. By using this function, we can easily replace characters and substrings in strings. It should be noted that this function returns a new string object and the original string will not be modified.

I hope the sample code provided in this article can help you better understand and use the String.replace() function. Using this function can make your code more concise and readable, and improve the maintainability of your code.

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