The construction order of Java classes

1. No object construction

public class Test {public      static int k = 0;     public static int n =;           public static int i = print ("i"); static {           print ("static block");       } {          print ("Building block");       } public int j = Print ("J");   Public Test (String str) {           System.out.println (++k) + ":" + str + "i=" + i + "n=" + N);          ++i;           ++n;       }    public static int print (String str) {           System.out.println ((++k) + ":" + str + "i=" + i + "n=" + N);          ++n;           return ++i;           }      public static void Main (string[] strings) {              }   }

Constructs static variables and static blocks of code when the class is loaded.

Order according to the defined order.

The result is:

1:i i=0 n=99
2: Static block I=1 n=100

Constructing objects in 2.main functions

public class Test {public      static int k = 0;     public static int n =;           public static int i = print ("i"); static {           print ("static block");       } {          print ("Building block");       } public int j = Print ("J");   Public Test (String str) {           System.out.println (++k) + ":" + str + "i=" + i + "n=" + N);          ++i;           ++n;       }    public static int print (String str) {           System.out.println ((++k) + ":" + str + "i=" + i + "n=" + N);          ++n;           return ++i;           }      public static void Main (string[] strings) {           Test t = new Test ("Init");       }   }

The first two ibid.

When constructing an object, the non-static variable in the object is constructed before the constructor is called.

Variables of non-static classes are constructed in the order defined.

The result is:

1:i i=0 n=99
2: Static block I=1 n=100
3: Construction block i=2 n=101
4:j i=3 n=102
5:init i=4 n=103

3. The class contains a static object

public class Test {public      static int k = 0;     public static int n = 99; public static Test T1 = new Test ("T1");                 public static int i = print ("i"); static {           print ("static block");       } {          print ("Building block");       } public int j = Print ("J");   public static Test t2 = new test ("T2"); Public Test (String str) {           System.out.println (++k) + ":" + str + "i=" + i + "n=" + N);          ++i;           ++n;       }    public static int print (String str) {           System.out.println ((++k) + ":" + str + "i=" + i + "n=" + N);          ++n;           return ++i;           }      public static void Main (string[] strings) {           Test t = new Test ("Init");       }   }

Static type variables, objects, and code blocks are constructed in the order defined.

When constructing a static object, because it is a construction object, as described in 2, a non-static variable is constructed before the constructor is called.

Results:

1: Construction block i=0 n=99
2:j I=1 n=100
3:t1 i=2 n=101
4:i i=3 n=102
5: Static block i=4 n=103
6: Construction block i=5 n=104
7:j i=6 n=105
8:t2 i=7 n=106
9: Construction Block i=8 n=107
10:j i=9 n=108
11:init i=10 n=109

4.static variable Initialization

public class Test {public      static int k = 0;     public static Test T1 = new Test ("T1");                 public static int i = print ("i"); public static int n = 99; static {           print ("static block");       } {          print ("Building block");       } public int j = Print ("J");   public static Test t2 = new test ("T2"); Public Test (String str) {           System.out.println (++k) + ":" + str + "i=" + i + "n=" + N);          ++i;           ++n;       }    public static int print (String str) {           System.out.println ((++k) + ":" + str + "i=" + i + "n=" + N);          ++n;           return ++i;           }      public static void Main (string[] strings) {           Test t = new Test ("Init");       }   }

The default initialization is then assigned.

Results:

1: Construction block i=0 n=0
2:j I=1 N=1
3:t1 i=2 n=2
4:i i=3 n=3
5: Static block i=4 n=99
6: Construction block i=5 n=100
7:j i=6 n=101
8:t2 i=7 n=102
9: Construction Block i=8 n=103
10:j i=9 n=104
11:init i=10 n=105