解决Kotlin 类在实现多个接口,覆写多个接口中相同方法冲突的问题

package net.println.kotlin.chapter4

/**
 * @author:wangdong
 * @description:类实现接口的冲突问题
 */

interface B{
  fun x(): Int = 1
}

interface C{
  fun x(): Int = 0
}

/**一个类实现了两个接口，两个接口中的方法相同，这个类在覆写的时候就会出现冲突*/
class D: B,C{
  //当下面两个方法同时存在的时候，就会报方法相同的冲突
  override fun x(): Int {
    return super<B>.x()
  }

  override fun x(): Int {
    return super<C>.x()
  }
}

package net.println.kotlin.chapter4

/**
 * @author:wangdong
 * @description:类继承类，实现接口的方法冲突问题
 * 接口方法可以有默认的实现
 * 签名一致且返回值相同的冲突
 * 子类（实现类）必须覆写冲突方法
 * super<[父类（接口）名]>.[方法名]([参数列表])
 */

abstract class A{
  open fun x(): Int = 5
}

interface B{
  fun x(): Int = 1
}

interface C{
  fun x(): Int = 0
}

/**一个类实现了两个接口，两个接口中的方法相同，这个类在覆写的时候就会出现冲突*/
/**采用分支模式解决冲突问题*/
class D(var y: Int = 0):A() ,B,C{

  //返回值一定要一样啊，例如：一定要是Int
  override fun x(): Int {
    println("call x(): Int in D")
    if (y > 0){
      return y
    }else if (y < -200){
      return super<C>.x()
    }else if (y < -100){
      return super<B>.x()
    }else{
      return super<A>.x()
    }
  }
}

fun main(args: Array<String>) {
  println(D(3).x())
  println(D(-10).x())
  println(D(-110).x())
  println(D(-230).x())
}
/**输出的结果*/
call x(): Int in D

call x(): Int in D

call x(): Int in D

call x(): Int in D

public class Java extends Language 
  implements JVMRunnable{  
  ...
}

public class Kotlin extends Language 
  implements JVMRunnable, FERunnable{  
  ...
}

public class Java extends Language 
  implements JVMRunnable{  
  public void runOnJVM(){    
    ...
  }
}

public class Kotlin extends Language 
  implements JVMRunnable, FERunnable{  
  public void runOnJVM(){    
    ...
  }  
  
  public void runOnFE(){    
    ...
  }
}

public abstract class JVMLanguage{  
  public void runOnJVM(){    
    ...
  }
}
    
public class Java extends JVMLanguage{

}

public class Kotlin extends JVMLanguage 
  implements FERunnable{  
  
  public void runOnFE(){    
    ...
  }
}

public interface JVMRunnable{
  default void runOnJVM(){    
    ...
  }
}
    
public class Java extends Language 
  implements JVMRunnable{

}
  
public class Kotlin extends Language 
  implements JVMRunnable, FERunnable{  
  public void runOnFE(){    
    ...
  }
}

abstract class Languageinterface JVMRunnable{  
  fun runOnJVM()
}

class DefaultJVMRunnable : JVMRunnable {  
  override fun runOnJVM() {
    println("running on JVM!")
  }
}

class Java(jvmRunnable: JVMRunnable) 
  : Language(), JVMRunnable by jvmRunnable

class Kotlin(jvmRunnable: JVMRunnable) 
  : Language(), JVMRunnable by jvmRunnable, FERunnable{  
  fun runOnFE(){    
    ...
  }
}