筆記

抽象abstract

1抽象類關(guān)鍵字墅拭，修飾類和方法可以放在訪問權(quán)限符public的前面或后面，一般放在后面

2抽象方法的個(gè)數(shù)沒有限制掀序，可以有也可以沒有普通的方法

3抽象類必有抽象的方法爹脾，反抽象方法的一定的是抽象類

案例：

package Demo02;

public abstract class Door {
   public abstract void open();
   public abstract void close();
}

子類一

package edu.xcdq.Demo01;

/**
 * @qvthor liuwenzheng
 * @date 2021/4/29 16:44
 */
public class KeypadDoor extends Door{

    public void open(){
        System.out.println("輸入密碼開門");
    }
    public void close(){
        System.out.println("輕輕關(guān)上");
    }

}

子類二

package edu.xcdq.Demo01;

/**
 * @qvthor liuwenzheng
 * @date 2021/4/29 16:45
 */
public class PowerDoor extends Door{
    public void open(){
        System.out.println("遙控開門");
    }
    public void close(){
        System.out.println("遙控關(guān)門");
    }
}

測試

package edu.xcdq.Demo01;

import Demo02.Door;

/**
 * @qvthor liuwenzheng
 * @date 2021/4/29 16:45
 */
public class Demo01 {
    public static void main(String[] args) {
        KeypadDoor keypadDoor = new KeypadDoor();
        keypadDoor.open();
        keypadDoor.close();


        PowerDoor powerDoor = new PowerDoor();
        powerDoor.close();
        powerDoor.open();
        Demo02.Door door = new Door() {
            @Override
            public void open() {
                System.out.println("臨時(shí)實(shí)現(xiàn)開門");
            }

            @Override
            public void close() {
                System.out.println("臨時(shí)實(shí)現(xiàn)關(guān)門");
            }
        };
        door.open();
        door.close();


    }
}

接口

1關(guān)鍵字interface，實(shí)現(xiàn)類的關(guān)鍵字implements

2接口中定義方法的聲明坡疼，沒有方法的方法體

3接口中的方法必須是公有的

package Demo03;

/**
 * @qvthor liuwenzheng
 * @date 2021/4/29 17:31
 */
public interface Door {
    public void open();
    public void close();
}

package Demo03;

/**
 * @qvthor liuwenzheng
 * @date 2021/4/29 17:33
 */
public class KeypadDoor implements Door{
    @Override
    public void close() {
        System.out.println("鍵盤開門");
    }

    @Override
    public void open() {
        System.out.println("鍵盤關(guān)門");
    }
}

package Demo03;

/**
 * @qvthor liuwenzheng
 * @date 2021/4/29 17:32
 */
public class PowerDoor implements Door{
    @Override
    public void open() {
        System.out.println("開門");
    }

    @Override
    public void close() {
        System.out.println("關(guān)門");
    }
}

調(diào)用

package Demo03;

/**
 * @qvthor liuwenzheng
 * @date 2021/4/29 17:43
 */
public class Demo03 {
    public static void main(String[] args) {
        KeypadDoor keypadDoor = new KeypadDoor();
        keypadDoor.open();
        keypadDoor.close();

        //可以用接口的類型  接受實(shí)現(xiàn)類創(chuàng)建的對象
        Door powerDoor = new PowerDoor();
        powerDoor.open();
        powerDoor.close();
    }
}

接口中的靜態(tài)常量

由于接口是規(guī)范的彬呻，實(shí)現(xiàn)類必須包含其中的屬性和方法，因此屬性public static final原本的屬性變成了靜態(tài)常量

public interface Door {
    //接口的靜態(tài)常量
    String desc = "是個(gè)門注意安全";
  //  public static final String desc = "是個(gè)門注意安全";
    public void open();
    public void close();
}

接口的兩個(gè)例外

默認(rèn)方法柄瑰，只能通過實(shí)現(xiàn)類的對象調(diào)用keypadDoor.test01();

靜態(tài)方法闸氮，只能通過接口名的方式調(diào)用Door.test02();

package Demo03;

/**
 * @qvthor liuwenzheng
 * @date 2021/4/29 17:31
 */
//接口， 定義門的規(guī)范
public interface Door {
    //接口的靜態(tài)常量
    String desc = "是個(gè)門注意安全";
  //  public static final String desc = "是個(gè)門注意安全";
    public void open();
    public void close();

    public default void test01(){
        System.out.println("接口中的靜態(tài)方法");
    }
    public static void test02(){
        System.out.println("接口中的靜態(tài)方法");
    }
}

keypadDoor.test01();
Door.test02();

總代碼

Demo01

package edu.xcdq.Demo01;

import Demo02.Door;

/**
 * @qvthor liuwenzheng
 * @date 2021/4/29 16:45
 */
public class Demo01 {
    public static void main(String[] args) {
        KeypadDoor keypadDoor = new KeypadDoor();
        keypadDoor.open();
        keypadDoor.close();


        PowerDoor powerDoor = new PowerDoor();
        powerDoor.close();
        powerDoor.open();
        Demo02.Door door = new Door() {
            @Override
            public void open() {
                System.out.println("臨時(shí)實(shí)現(xiàn)開門");
            }

            @Override
            public void close() {
                System.out.println("臨時(shí)實(shí)現(xiàn)關(guān)門");
            }
        };
        door.open();
        door.close();


    }
}

Door

package edu.xcdq.Demo01;

public class Door {
    public void Door(){
        System.out.println("開門");
    }
   public void close(){
       System.out.println("關(guān)門");
   }

}

KeypadDoor

package edu.xcdq.Demo01;

/**
 * @qvthor liuwenzheng
 * @date 2021/4/29 16:44
 */
public class KeypadDoor extends Door{

    public void open(){
        System.out.println("輸入密碼開門");
    }
    public void close(){
        System.out.println("輕輕關(guān)上");
    }

}

PowerDoor

package edu.xcdq.Demo01;

/**
 * @qvthor liuwenzheng
 * @date 2021/4/29 16:45
 */
public class PowerDoor extends Door{
    public void open(){
        System.out.println("遙控開門");
    }
    public void close(){
        System.out.println("遙控關(guān)門");
    }
}

Demo02.Demo.1

package Demo02;

/**
 * @qvthor liuwenzheng
 * @date 2021/4/29 16:45
 */
public class Demo01 {
    public static void main(String[] args) {
        KeypadDoor keypadDoor = new KeypadDoor();
        keypadDoor.open();
        keypadDoor.close();

        PowerDoor powerDoor = new PowerDoor();
        powerDoor.close();
        powerDoor.open();


    }
}

Door

package Demo02;

public abstract class Door {
   public abstract void open();
   public abstract void close();

   public void test(){
      System.out.println("可以有普通的方法");
   }
}

KeypadDoor

package Demo02;

/**
 * @qvthor liuwenzheng
 * @date 2021/4/29 16:44
 */
public class KeypadDoor extends Door {
    public void open(){
        System.out.println("");
    }
    public void close(){
        System.out.println("");
    }
}

PowerDoor

package Demo02;

/**
 * @qvthor liuwenzheng
 * @date 2021/4/29 16:45
 */
public class PowerDoor extends Door {
    public void open(){
        System.out.println("");
    }
    public void close(){
        System.out.println("");
    }
}

Demo03.Demo01接口

package Demo03;

/**
* @qvthor liuwenzheng
* @date 2021/4/29 17:43
*/
public class Demo01 {
   public static void main(String[] args) {
       KeypadDoor keypadDoor = new KeypadDoor();
       keypadDoor.open();
       keypadDoor.close();

       //可以用接口的類型  接受實(shí)現(xiàn)類創(chuàng)建的對象
       Door powerDoor = new PowerDoor();
       powerDoor.open();
       powerDoor.close();

       keypadDoor.test01();
       Door.test02();
   }
}

Door

package Demo03;

/**
 * @qvthor liuwenzheng
 * @date 2021/4/29 17:31
 */
//接口教沾， 定義門的規(guī)范
public interface Door {
    //接口的靜態(tài)常量
    String desc = "是個(gè)門注意安全";
  //  public static final String desc = "是個(gè)門注意安全";
    public void open();
    public void close();

    public default void test01(){
        System.out.println("接口中的靜態(tài)方法");
    }
    public static void test02(){
        System.out.println("接口中的靜態(tài)方法");
    }
}

KeypadDoor

package Demo03;

/**
 * @qvthor liuwenzheng
 * @date 2021/4/29 17:33
 */
public class KeypadDoor implements Door{
    @Override
    public void close() {
        System.out.println("鍵盤開門");
    }

    @Override
    public void open() {
        System.out.println("鍵盤關(guān)門");
    }
}

PowerDoor

package Demo03;

/**
 * @qvthor liuwenzheng
 * @date 2021/4/29 17:32
 */
public class PowerDoor implements Door{
    @Override
    public void open() {
        System.out.println("開門");
    }

    @Override
    public void close() {
        System.out.println("關(guān)門");
    }
}