What is the difference between Int and Integer in Java?

The differences are as follows:

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1. Int is a basic type and can store numerical values ​​directly. ; and integer is a reference data type.

2. The declaration of Int does not require instantiation, and the initial value after the variable is declared is 0; Integer is a class with an initial value of null and needs to be instantiated before the variable data can be processed.

3. The Integer class is a packaging class of int. In actual development, Integer is regarded as an object and can perform data conversion and other operations.

Example:

        Integer num1 = 200;   
        Integer num2 = 200;           
        System.out.println("num1==num2: "+(num1==num2));                    
        Integer num3 = 100;   
        Integer num4 = 100;   
        System.out.println("num3==num4: "+(num3==num4));

Output result:

num1==num2:false
num3==num4:true

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Analysis:

First of all, we must clarify the difference between the equal method and ==:

equals() compares whether the values ​​(contents) of the two objects are the same.

"==" compares whether the references (memory addresses) of two objects are the same, and is also used to compare whether the variable values ​​of two basic data types are equal.

java definition: During automatic boxing, for values ​​​​from –128 to 127, after they are boxed into Integer objects, they will be stored in memory and reused. There will always be only one object and if it exceeds If the value between –128 and 127 is specified, the boxed Integer object will not be reused, which is equivalent to creating a new Integer object each time it is boxed;

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