Java object-oriented construction code block entry example

1. Basic Concepts

　　1. Construct a code block to initialize all objects.

　　2. Constructor, which only initializes the corresponding object.

　　3. Local code blocks, which control the life cycle of local variables.

2. Example code

1  class Person
 2  {
 3      private  int age;
 4      // Construct the code block. Initialize all objects. 
5      {
 6          System.out.println("Construction code block..." );
 7      }
 8      
9      // The constructor only initializes the corresponding object. 
10      Person ()
 11      {
 12          System.out.println("person..." );
 13      }
 14      Person ( int age)
 15      {
 16          this .age = age;
 17         System.out.println("person(age)..." );
 18      }
 19      // General function. Executed when called. 
20      public  void code()
 21      {
 22          int x = 8 ;
 23          System.out.println("x="+ x);
 24      }
 25  }
 26  class CodeDemo
 27  {
 28      public  static  void main(String[] args)
 29      {
 30          Person p1 = new Person();
 31          Person p2 = newPerson(4 );
 32              
33          // Local code block, which controls the life cycle of local variables. 
34          {
 35              int x = 5 ;
 36              System.out.println("x="+ x);
 37          }
 38          p1.code();
 39      }
 40 }

3. Code running