java constructor 24

Constructor

Constructor is part of the class.
Role: initialize an object and returns the address of the object.

	构造器的格式：
	        修饰符 类名(形参列表){
	        
	        }

• Modifiers: stage with all public.
• Class Name: The name of the constructor must be the name of the current class, otherwise an error!
• The constructor can not declare the return value type, default return address of an object reference.
• Parameter list: with the same method. (Data type parameter variable 1, variable data type parameter 2, ...)

Constructor Category:

1. No argument constructor.
2. There constructor parameter.

Action constructor : initialize an object and returns the address of the object.
Constructor initializes the object format : class name = new Object Name constructor;

Builder considerations:

• Just write a class, it will default comes with a no-argument constructor.
• But if he wrote a constructor have parameters, the default no-argument constructor disappeared at this time require the programmer to write a no-argument constructor to use it.

Examples of non-argument constructor:

public class ConstructorDemo01 {
    public static void main(String[] args) {
        // 初始化对象
        Wolf qpl = new Wolf();
        System.out.println(qpl);
    }
}

class Wolf{
    // 1.无参数构造器。
    public Wolf(){
        System.out.println("无参数构造器被触发指向，返回对象的地址~~");
    }
}

There is overloaded constructor:
can be provided with a constructor parameter can also provide a no-argument constructor for the class, we call them exist as overloaded constructor.

No role configuration parameters:
Object to initialize a class returns inside the member variables default values. ( In general programming device must be provided constructor with no arguments )

There are construction parameters of the role:
object initialization of a class returns can be assigned immediately to the member variable objects in the object initialization time. Animal taiTi = new Animal ( "Teddy", 2, 'male'); (immediate Assignment)

public class AnimalDemo {
    public static void main(String[] args) {
        // 1.调用无参数构造器初始化一个对象返回：对象都是采用默认值。
        Animal jinMao = new Animal();
        jinMao.setName("金毛");
        jinMao.setAge(2);
        jinMao.setSex('公');
        System.out.println(jinMao.getName());
        System.out.println(jinMao.getAge());
        System.out.println(jinMao.getSex());
        jinMao.run();

        // 2.调用有参数构造器初始化一个对象返回：对象都会直接赋值。
        Animal taiTi = new Animal("泰迪",2 ,  '公');
        System.out.println(taiTi.getName());
        System.out.println(taiTi.getAge());
        System.out.println(taiTi.getSex());
        taiTi.run();
    }
}

class Animal{
    // 1、成员变量（属性）: 建议私有。
    private String name ;
    private int age ;
    private char sex;

    // 3、无参数构造器默认的。（必须提供的）
    public Animal() {
        System.out.println("无参数构造器被执行~~~");
    }
    // 4、有参数构造器（建议提供）
    public Animal(String name, int age, char sex) {
        System.out.println("有参数构造器被触发执行~~~~");
        this.name = name;
        this.age = age;
        this.sex = sex;
    }

    // 5.普通方法
    public void run(){
        System.out.println("名字是："+name+",年龄是："+age+" , 性别是："+sex+" , 跑的贼溜~~~~~");
    }

    // 2、getter+setter方法：暴露成员变量的取值和赋值。（自动生成）。
    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public char getSex() {
        return sex;
    }

    public void setSex(char sex) {
        this.sex = sex;
    }
}

Note:
No argument constructor argument constructor and there is in the programming can be generated directly by the tool

Right-click -> select Generate-> select Constructor-> Hold down the Shift key and click on the last one-and-click direct all OK is generated there argument constructor, then click Select None is generated, no arguments constructor.