SCJP(OCPJP) 考古題解析 第１２題（Drag&Drop）

Add methods to the Beta class to make it compile correctly.

class Alpha {
      public void bar(int... x) {}

      public void bar(int x) {}
}

public class Beta extends Alpha {
      Place here　public void bar(int x){}                
      Place here　public int bar(String x){return 1; }
      Place here　public void bar(int x, int y){}       
}


Methods

private void bar(int x){}

public void bar(int x){}

public int bar(String x){return 1;}

public Alpha bar(int x){}

public void bar(int x, int y){}

public int bar(int x){return x;}

解析：

Ｘ  private void bar(int x){} － 繼承來的方法存取只能更開放：public>protected>(default)>private

Ｖ  public void bar(int x){} － Overriding

Ｖ  public int bar(String x){return 1;} － Overloading

Ｘ  public Alpha bar(int x){}  － Overriding不允許回傳不同型態 

Ｖ  public void bar(int x, int y){} －  Overloading  

Ｘ  public int bar(int x){return x;} － Overriding不允許回傳不同型態