【Kotlin】匿名类和伴生类

1 匿名类

        1）无继承

fun main() {var obj = object {var name: String = "zhang"override fun toString(): String {return name}}println(obj) // zhang
}

         2）有继承

fun main() {var obj = object: People {var name: String = "zhang"override fun play() {println("play, $name")}}obj.play() // play, zhang
}interface People {fun play()
}

2 单例

2.1 案例一

        1）object 单例

fun main() {var singleton = Singletonprintln(singleton)
}object Singleton {var name = "zhang"override fun toString(): String {return return name}
}

        2）对应的 java 类

        Singleton.java

public final class Singleton {private static String name;public static final Singleton INSTANCE;static {INSTANCE = new Singleton();name = "zhang";}private Singleton() {}public final String getName() {return name;}public final void setName(String var1) {name = var1;}public String toString() {return name;}
}

        java 中调用如下。

Singleton singleton = Singleton.INSTANCE;
System.out.println(singleton);

2.2 案例二

        1）object 单例

fun main() {var stu = Student.Tools.create("zhang")println(stu) // zhangprintln(Student.Tools.age) // 15
}class Student(var name: String) {object Tools {var age: Int = 15fun create(name: String): Student {return Student(name)}}override fun toString(): String {return name}
}

        2）对应的 java 类

        Student.java

public final class Student {private String name;public Student(String name) {this.name = name;}public final String getName() {return this.name;}public final void setName(String var1) {this.name = var1;}public String toString() {return this.name;}public static final class Tools {private static int age;public static final Tools INSTANCE;static {INSTANCE = new Tools();age = 15;}private Tools() {}public final Student create(String name) {return new Student(name);}public final int getAge() {return age;}public final void setAge(int var1) {age = var1;}}
}

        java 中调用如下。

Student stu = Student.Tools.INSTANCE.create("zhang");
System.out.println(stu);
System.out.println(Student.Tools.INSTANCE.getAge());

3 伴生类

        1）companion object

fun main() {var stu = Student.create("zhang")println(stu) // zhangprintln(Student.age) // 15
}class Student(var name: String) {companion object Tools {var age: Int = 15fun create(name: String): Student {return Student(name)}}override fun toString(): String {return name}
}

        2）对应的 java 类

        Student.java

public final class Student {private String name;private static int age = 15;public static final Tools Tools = new Tools(();public Student(String name) {this.name = name;}public final String getName() {return this.name;}public final void setName(String var1) {this.name = var1;}public String toString() {return this.name;}public static final class Tools {private Tools() {}public final Student create(String name) {return new Student(name);}public final int getAge() {return Student.age;}public final void setAge(int var1) {Student.age = var1;}}
}

         java 中调用如下。

Student stu = Student.Tools.create("zhang");
System.out.println(stu);
System.out.println(Student.Tools.getAge());