JAVA basics/Lesson 24th: What does THIS mean in classes and objects/JAVA? Passing parameter xiangjie and java xiangjie

JAVA basics/Lesson 24th: What does THIS mean in classes and objects/JAVA? Passing parameter xiangjie and java xiangjie

1. the keyword "this" is equivalent to "I" in Mandarin, for example:

When James says "I have eaten", "I" represents James
When Xiaohong says "I have eaten", "I" represents Xiaohong.
"I" represents the current character.

1. this indicates the current object:

Public class Hero {String name; // float hp; // float armor; // armor int moveSpeed; // moving speed // print the virtual address in the memory public void showAddressInMemory () {System. out. println ("print the virtual address this saw:" + this);} public static void main (String [] args) {Hero garen = new Hero (); garen. name = "galun"; // print the object directly. The virtual address of the object in the memory is displayed. // format: Hero @ c17164 c17164: virtual address, the obtained address is not necessarily the same as that of System. out. println ("the virtual address seen by the Print Object:" + garen); // call showAddressInMemory to print this of the object and display the same virtual address garen. showAddressInMemory (); Hero teemo = new Hero (); teemo. name = "Timo"; System. out. println ("the virtual address seen by the Print Object:" + teemo); teemo. showAddressInMemory ();}}

2. Access the attributes of an object using the this keyword:

Public class Hero {String name; // float hp; // float armor; // armor int moveSpeed; // moving speed // The same parameter name and attribute name // In the method body, only the parameter name public void setName1 (String name) {name = name;} can be accessed ;} // to avoid problems in setName1, the parameter name must use other variable names public void setName2 (String heroName) {name = heroName ;} // use this to access the public void setName3 (String name) {// name indicates the parameter name // this. name indicates the property name this. name = name;} public static void main (String [] args) {Hero h = new Hero (); h. setName1 ("teemo"); System. out. println (h. name); h. setName2 ("garen"); System. out. println (h. name); h. setName3 ("Dead song"); System. out. println (h. name );}}

3. Use this to call other constructor methods:

To call another constructor in one constructor, you can use this ()

Public class Hero {String name; // float hp; // float armor; // armor int moveSpeed; // moving speed // The construction method with one parameter public Hero (String name) {System. out. println ("constructor of a parameter"); this. name = name;} // constructor with two parameters: public Hero (String name, float hp) {this (name); System. out. println ("constructor of Two Parameters"); this. hp = hp;} public static void main (String [] args) {Hero teemo = new Hero ("Timo", 383); System. out. println (teemo. name );}}

2. There are two types of variables: basic type and class type. parameters are also variables. Therefore, passing parameters can be divided into basic type parameters and class type parameters:

1. input parameters of the basic type:

The basic type parameter outside the method cannot be modified within the Method

Public class Hero {String name; // float hp; // float armor; // armor int moveSpeed; // movement speed public Hero () {}// blood return public void huixue (int xp) {hp = hp + xp; // after blood return, the blood bottle = 0 xp = 0;} public Hero (String name, float hp) {this. name = name; this. hp = hp;} public static void main (String [] args) {Hero teemo = new Hero ("Timo", 383); // blood bottle, the value is 100 int xueping = 100; // Timo uses this blood bottle to restore teemo. huixue (xueping); System. out. println (xueping );}}

2. Reference and =

If a variable is of the basic type, such as int hp = 50, we directly take over the variable named hp, and = indicates the meaning of the value assignment.
If a variable is of the class type, for example, Hero h = new Hero (); we call h a reference.

= No longer the meaning of the value assignment, = indicates the meaning of the point:

For example, Hero h = new Hero (); References h and points to a Hero object.

3. Passing parameters of the class type:

The class type is also called reference.
The references of row 24th are different from those of row 17th hero.
By calling garen. attack (teemo, 100); both references point to the same object
Therefore, the hpvalue of this object is changed in Row 3 hero. hp = hero. hp-damage;
Therefore, in Row 3, The hpvalue of the object is the changed value.

Public class Hero {String name; // float hp; // float armor; // armor int moveSpeed; // public Hero (String name, float hp) {this. name = name; this. hp = hp;
} // Attack a Hero and let him lose the blood of the damage point public void attack (hero, int damage) {Hero. hp = hero. hp-damage;} public static void main (String [] args) {Hero teemo = new Hero ("Timo", 383); Hero garen = new Hero ("galun ", 616); garen. attack (teemo, 100); System. out. println (teemo. hp );}}