Interpretation of Java documentation: Functional analysis of the valueOf() method of the Short class

Interpretation of Java documentation: function analysis of the valueOf() method of the Short class requires specific code examples

In Java, the Short class is a wrapper class that will short Type data is encapsulated as an independent object. The Short class provides many methods to operate the encapsulated short type data, one of the commonly used methods is valueOf().

The valueOf() method is defined as follows:

public static Short valueOf(short s)

The function of this method is to convert a short type value into a Short object. Let's analyze the function of this method in detail.

1. Value conversion:
   The valueOf() method passes the value of short type as a parameter, and then returns the corresponding Short object. This process is to convert a basic data type into an object of the corresponding reference type, which is the encapsulation process.

   For example, we have a value of type short:

   short num = 10;

   We can use the valueOf() method to convert it to a Short object:

   Short shortObj = Short.valueOf(num);

2. Autoboxing:
   In Java, basic data types can be automatically boxed into corresponding packaging class objects. This means that we can directly assign a value of type short to a variable of type Short without calling the valueOf() method.

   For example, we can also write like this:

   Short shortObj = num;

   This method will also encapsulate the short type value into a Short object.

3. Caching mechanism:
   The Short class optimizes the valueOf() method. For values ​​ranging from -128 to 127, the Short class will cache the corresponding objects. In this way, when the valueOf() method is called to obtain the corresponding objects of these values, the objects that already exist in the cache are actually returned instead of newly created objects. This caching mechanism can improve performance and save memory.

   For example, when we call the valueOf() method to obtain a corresponding object with a value ranging from -128 to 127, it will be obtained from the cache:

   Short shortObj1 = Short.valueOf(10);
   Short shortObj2 = Short.valueOf(10);
   
   System.out.println(shortObj1 == shortObj2);  // 输出true

   In the above code, shortObj1 and shortObj2 actually reference the Short object in the same cache, so they are equal.

It should be noted that when the incoming parameters exceed the cache range, the valueOf() method will still create a new Short object.

In summary, the valueOf() method of the Short class can convert a short type value into a corresponding Short object. It can be implemented through value conversion or automatic boxing, and also uses caching mechanisms to improve performance. The code example is as follows:

public class ShortExample {
    public static void main(String[] args) {
        short num = 10;
        
        // 值的转换
        Short shortObj = Short.valueOf(num);
        System.out.println("Value of shortObj: " + shortObj);
        
        // 自动装箱
        Short shortObj2 = num;
        System.out.println("Value of shortObj2: " + shortObj2);
        
        // 缓存机制
        Short shortObj3 = Short.valueOf(10);
        Short shortObj4 = Short.valueOf(10);
        System.out.println(shortObj3 == shortObj4);  // 输出 true
    }
}

The above is the functional analysis and code example of the valueOf() method of the Short class. This method is very useful when processing short type data. I hope it will be helpful to you!

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