In this article, we’re going to take a look at how to parse strings in Java. We’ll start with a simple example of splitting a string by a regular expression. Then we’ll move on to more advanced topics like parsing strings with multiple delimiters and handling escape characters.
how to parse string java
String parsing is a common task in programming, whether it’s extracting data from a log file or converting user input into a different data type. In Java, there are a number of ways to parse strings.
The most common way to parse strings is by using the String.split() method. This method splits a string into an array of substrings based on a given delimiter. For example, the following code splits a string by the space character:
String str = “This is a test string”;
String[] parts = str.split(” “);
System.out.println(parts.length); // 4
System.out.println(parts); // [“This”, “is”, “a”, “test”, “string”]
In this example, the string is split into four parts: “This”, “is”, “a”, and “test string”.
If you want to use a regular expression as the delimiter, you can pass it as the second argument to the split() method. For example, the following code splits a string by any sequence of one or more non-word characters:
String str = “This is a test string”;
String[] parts = str.split(“\\W+”);
System.out.println(parts); // [“This”, “is”, “a”, “test”, “string”]
In this example, the string is split into four parts: “This”, “is”, “a”, and “test string”.
If you want to limit the number of parts that the string is split into, you can pass a third argument to the split() method. This argument specifies the maximum number of parts that the string can be split into. For example, the following code splits a string into two parts at most:
String str = “This is a test string”;
String[] parts = str.split(” “, 2);
System.out.println(parts); // [“This”, “is a test string”]
In this example, the string is split into two parts: “This” and “is a test string”.
Another way to parse strings is by using the StringTokenizer class. This class is designed specifically for splitting strings. It has a number of advantages over the split() method, including being able to specify multiple delimiters and handling escape characters.
For example, the following code splits a string by the space character and the comma character:
String str = “This, is a test string”;
StringTokenizer st = new StringTokenizer(str, ” ,”);
while (st.hasMoreTokens()) {
System.out.println(st.nextToken());
}
In this example, the string is split into four parts: “This”, “is”, “a”, and “test string”.