How does Java use the startsWith() and endsWith() functions of the String class to determine whether a string begins or ends with a specified character or substring?

Java is a very popular programming language with rich class libraries and functions. In terms of string processing, Java provides the String class, which has many functions to conveniently operate strings. This article will introduce the startsWith() and endsWith() functions in the String class, which can be used to determine whether a string begins or ends with a specified character or substring.

String class is a class used to represent strings in Java. It provides many functions for operating strings. Two of the most commonly used functions are startsWith() and endsWith(). The startsWith() function is used to determine whether a string begins with a specified character or substring, and the endsWith() function is used to determine whether a string ends with a specified character or substring.

First, let’s look at the usage of startsWith() function. Its use is very simple, just call the startsWith() function of the string object, and then pass in a specified character or substring as a parameter. Note that the startsWith() function is case-sensitive. If you want to achieve case-insensitive matching, you can use the toLowerCase() function to convert the string to lowercase before making a judgment.

The following is a sample code that uses the startsWith() function to determine whether a string begins with a specified character:

String str = "Hello World";
boolean startsWith = str.startsWith("Hello");
System.out.println(startsWith); // 输出：true

boolean startsWithIgnoreCase = str.toLowerCase().startsWith("hello");
System.out.println(startsWithIgnoreCase); // 输出：true

In the above code, we first define a string "Hello World" , and then use the startsWith() function to determine whether it starts with "Hello" and "hello" respectively. The first judgment returns true, because the string does start with "Hello"; the second judgment returns true, although "Hello" and "hello" are not exactly the same, but after converting the string to lowercase by calling the toLowerCase() function , the judgment result is true.

Next, let’s look at the usage of endsWith() function. It is also very simple, just call the endsWith() function of the string object, and then pass in a specified character or substring as a parameter.

The following is a sample code that uses the endsWith() function to determine whether a string ends with a specified character:

String str = "Hello World";
boolean endsWith = str.endsWith("World");
System.out.println(endsWith); // 输出：true

boolean endsWithIgnoreCase = str.toLowerCase().endsWith("world");
System.out.println(endsWithIgnoreCase); // 输出：true

In the above code, we first define a string "Hello World" , and then use the endsWith() function to determine whether it ends with "World" and "world" respectively. The first judgment returns true because the string does end with "World"; the second judgment returns true because although "World" and "world" are not exactly the same, the string is converted to lowercase by calling the toLowerCase() function. , the judgment result is true.

Through the above sample code, we can see that it is very simple to use the startsWith() and endsWith() functions to determine whether a string begins or ends with a specified character or substring. These two functions are very commonly used in actual string processing. They can easily determine the beginning and end of a string and perform corresponding processing.

To summarize, through the startsWith() and endsWith() functions of the String class in Java, we can easily determine whether a string begins or ends with a specified character or substring. These functions are very practical in actual programming and can simplify string processing operations. I hope this article will help you understand and use the startsWith() and endsWith() functions.

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