Java Chapter III Hands-on brain

public class Initializeblockdemo {

/**

* @param args

*/

public static void Main (string[] args) {

Initializeblockclass obj=new Initializeblockclass ();

System.out.println (Obj.field);

Obj=new Initializeblockclass (300);

System.out.println (Obj.field);

}

}

Class initializeblockclass{

The following sentence affects the initial value of the Field field before and after the initialization block

public int field=100;

{

field=200;

}

public int field=100;

public initializeblockclass (int value) {

This.field=value;

}

Public Initializeblockclass () {

}

}

The result is 100 300; it is obvious that the initialization block of a class in Java will run first only once, and if the variable is assigned a value in the class, it will change the value of the variable, including the Call function assignment.

Package demo;

Public class In extends father{

Public Static void Main (string[] args) {

TODO auto-generated Method stub

In x;

x = new in ();

}

}

class father{

{

int i = 100;

System. out. println (i);

}

}

The result is 100 shows that when there is an inheritance relationship between multiple classes, creating a subclass object causes the parent class to initialize the block's execution

Package demo;

Public class in{

Static int n = 10;

Public Static void Main (string[] args) {

Stac s = new Stac ();

N = S.fuzhi ();

S.Output(n);

}

}

class stac{

int a = 20;

int Fuzhi () {

int x;

x = A;

return x;

}

Static void Output (int b) {

System. out. println (b);

}

}

Result is 20

Using static methods to access instance members of a class is to assign an instance variable of the class to a static variable and then output it with a static method.

Java Chapter III Hands-on brain