New features in Java 12: How to use the new String API for string truncation and padding

New features in Java 12: How to use the new String API for string truncation and padding

Java 12 is the latest version of the Java platform, which brings many exciting new features and Improve. One of the important updates is the introduction of a new String API in terms of string operations, making string truncation and filling simpler and more efficient. This article introduces these new APIs and shows how to use them with code examples.

Prior to Java 12, string truncation and padding may need to be implemented using regular expressions or complex logic. But in Java 12, we can use the new String API to achieve the same effect, and the code is more concise and easier to understand. Here are some examples of how to use the new String API for string truncation and padding.

1. String truncation (truncate)

In some cases, we may want to limit the maximum length of the string, truncate the excess part and add ellipses. Prior to Java 12, some logic might need to be written to handle this requirement. However, using the new String API, we can easily achieve this by calling the String::truncate method.

String str = "This is a long string that needs to be truncated.";
String truncatedStr = str.truncate(20); // 截断到20个字符
System.out.println(truncatedStr); // 输出：This is a long string...

When using the truncate method, we specify the maximum length as a parameter and get the truncated string. If the length of the original string is less than or equal to the maximum length, the original string will be returned.

2. String padding (pad)

In some cases, we want to pad the string to a specified length in order to align or beautify the output. Before Java 12, we needed to write some logic to achieve this requirement. However, using the new String API, we can easily achieve this by calling the String::padStart and String::padEnd methods.

padStart method pads the specified characters at the beginning of the string until the specified length is reached.

String str = "Hello";
String paddedStr = str.padStart(10, '0'); // 在开头填充'0'，直到达到10个字符
System.out.println(paddedStr); // 输出：000000Hello

padEndThe method pads the specified characters at the end of the string until the specified length is reached.

String str = "Hello";
String paddedStr = str.padEnd(10, '0'); // 在末尾填充'0'，直到达到10个字符
System.out.println(paddedStr); // 输出：Hello00000

When using these two methods, we need to specify the padded string length and padded characters. If the length of the original string is less than or equal to the specified length, the original string will be returned.

3. Compound operation

In addition to using the string truncation and filling methods alone, we can also perform compound operations. For example, we can first truncate the string and then pad it to a specified length.

String str = "This is a long string that needs to be truncated and padded.";
String truncatedAndPaddedStr = str.truncate(20).padEnd(30, '-'); // 截断到20个字符，并在末尾填充'-',直到达到30个字符
System.out.println(truncatedAndPaddedStr); // 输出：This is a long string-----

This example first truncates the string to 20 characters, then pads '-' at the end until it reaches 30 characters.

Through these examples, we can see that the new String API introduced in Java 12 makes string truncation and filling simpler and more efficient. We no longer need to write complex logic or use regular expressions to achieve these functions. Using the truncate and padStart, padEnd methods, we can easily handle string truncation and padding needs, making the code more readable and maintainable.

To summarize, the new String API in Java 12 provides easy methods for string truncation and padding. By using these new APIs, we can handle string operations more easily, improving the readability and maintainability of our code. Hopefully the examples in this article will help readers learn and understand how to use these new APIs.

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