Interpretation of Java documentation: Detailed introduction to the append() method of the StringBuilder class

Interpretation of Java documentation: Detailed introduction to the append() method of the StringBuilder class

Java provides the StringBuilder class as a variable string type, which provides A series of methods to manipulate strings, one of the most commonly used methods is the append() method. This article will introduce the append() method of the StringBuilder class in detail and attach specific code examples.

The StringBuilder class was introduced in Java 5 to replace the StringBuffer class, and compared to the StringBuffer class, the StringBuilder class has higher performance. The core feature of the StringBuilder class is that its objects are mutable, that is, you can use the append() method to add character sequences or values ​​of other data types without creating a new StringBuilder object.

The append() method is used to append the specified data to the end of the StringBuilder object. There are many overloaded forms of this method, which can accept various types of parameters: char type characters, strings, Boolean values, numeric types, etc. Below we will introduce these overloaded forms one by one.

1. append(char c): This method accepts a char type parameter and appends the character to the end of the StringBuilder.

Sample code:

StringBuilder sb = new StringBuilder();
sb.append('H');
sb.append('e');
sb.append('l');
sb.append('l');
sb.append('o');
System.out.println(sb.toString());   // 输出结果为 "Hello"

2. append(String str): This method accepts a string parameter and appends the string to the end of the StringBuilder.

Sample code:

StringBuilder sb = new StringBuilder();
sb.append("Hello");
sb.append(" ");
sb.append("world");
System.out.println(sb.toString());   // 输出结果为 "Hello world"

3. append(boolean b): This method accepts a Boolean parameter, converts the Boolean value into a string and appends it to the end of the StringBuilder .

Sample code:

StringBuilder sb = new StringBuilder();
sb.append(true);
sb.append(" ");
sb.append(false);
System.out.println(sb.toString());   // 输出结果为 "true false"

4. append(int i): This method accepts an integer parameter, converts the integer into a string and appends it to the end of the StringBuilder.

Sample code:

StringBuilder sb = new StringBuilder();
sb.append(123);
sb.append(" ");
sb.append(-456);
System.out.println(sb.toString());   // 输出结果为 "123 -456"

In addition to the four overloaded forms introduced above, there are many other overloaded forms, such as the append() method that accepts long type parameters, accept The append() method of float type parameters, etc. Through these overloaded forms, we can easily append various types of data to the end of the StringBuilder object.

In actual programming, we often need to splice strings. If you use the String class to splice strings, each splicing will create a new String object, which will consume a lot of memory. Using the append() method of StringBuilder to splice strings not only avoids the cost of creating new objects, but also greatly improves execution efficiency.

Summary:

• The StringBuilder class provides the append() method to append strings or other types of data to the end of a string sequence.
• The append() method has multiple overloaded forms and can accept different types of parameters.
• Using the append() method of StringBuilder for string splicing can avoid performance overhead.

I hope that through this article, I can have a more detailed understanding of the append() method of the StringBuilder class in the Java document, and that it can be flexibly used in actual development.

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