接口中具有多态性的消费者

Question

最后我自己解决了问题 事实证明，消费者可以改变 并通过接口让我的xxx_dialogs和Compulsory使用openDialog函数。

产品、客户的数据 bean 开始

public class Prod extends MyBean { 
    private String P_NO = "";       
    private setP_NO(String p_no){
        P_NO= p_no;
    }
    private String getP_NO(){
        return P_NO;
    }
}   

public class Cust extends MyBean { 
    private String CUST_NO = "";   
....
}   

public class MyView{
　　TextField textFieldP_NO;
　　Button btnProd;
　　Button btnCust;
　　public MyView (){
      //...constructor...
    }
    btnProd.addClickListener(e -> {
        Prod_Dialog p_dlg = new Prod_Dialog();
        //fix before
        //p_dlg.openDialog(p -> textFieldP_NO.setValue(p.getP_NO()));
        //fix after
        p_dlg.openDialog(p -> textFieldP_NO.setValue(((PROD_Dialog.Prod) p).getP_NO()));
    });
    btnCust.addClickListener(e -> {
        Cust_Dialog c_dlg = new Cust_Dialog();
        //fix before
        //c_dlg.openDialog(c -> textFieldP_NO.setValue(c.getCUST_NO()));
        //fix after
        c_dlg.openDialog(c -> textFieldP_NO.setValue(((CUST_Dialog.Cust) c).getCUST_NO()));
    }); 
} 

[接口] 修复参数消费者可以多态

public interface BaseDialog {
    //fix before just for prodct. That's bad....
    //public abstract void openDialog(Consumer<Prod> selectionAction);
    
    //fix after that can service any MyBean...
    public abstract void openDialog(Consumer<? extends MyBean> selectionAction);
}

[Dialog] with Prod_Dialog and cust_Dialog thougth clickok method pass Consumer＜Prod＞ or Consumer＜Cust＞

//fix before
//public class Prod_Dialog {
//fix after 
public class Prod_Dialog implements BaseDialog{
  private Button btnOk;  
  ...
  //fix before
  //public void openDialog(Consumer<Prod> selectionAction) {
  //fix after     
  public void openDialog(Consumer<? extends MyBean> selectionAction) {
      btnOk.addClickListener(e -> {
        //fix before
        // Prod sel_prod = grid.asSingleSelect().getValue();
        // String p_no = sel_prod.getP_NO(); //get user selected p_no
        
        // Prod prod = new Prod();
        // prod.setP_NO(p_no);        
        // selectionAction.accept(prod);
        
        //fix after that is magic point for me, by Consumer Transformation
        clickOK((Consumer<Prod>) selectionAction); 
      }
  }
  public void clickOK(Consumer<Prod> selectionAction) {
    Prod sel_prod = grid.asSingleSelect().getValue();
    String p_no = sel_prod.getP_NO(); //get user selected p_no
    
    Prod prod = new Prod();
    prod.setP_NO(p_no);        
    selectionAction.accept(prod); 
  }
}   

public class Cust_Dialog implements BaseDialog{
    private Button btnOk;  
    ...
    public void openDialog(Consumer<? extends MyBean> selectionAction) {
      btnOk.addClickListener(e -> {
        //fix before
        // Cust sel_cust = grid.asSingleSelect().getValue();
        // String c_no = sel_cust.getCUST_NO(); //get user selected p_no
        
        // Cust cust = new Cust();
        // Cust.setCUST_NO(c_no);        
        // selectionAction.accept(cust); 
        //fix after
        clickOK((Consumer<Cust>) selectionAction); //that is magic point for me, by Consumer Transformation
      }
    }
  
    public void clickOK(Consumer<Cust> selectionAction) {
    Prod sel_cust = grid.asSingleSelect().getValue();
    String c_no = sel_prod.getCUST_NO(); //get user selected p_no
    
    Cust cust = new Cust();
    cust.setCUST_NO(c_no);        
    selectionAction.accept(cust); //that is magic point for me  
    }
}   

Answer 1

你的工作实现类代码方法签名

public void openDialog(Consumer<PROD> selectionAction)

与接口签名不同

public abstract void openDialog(Consumer<? extends MyBean> selectionAction);

不要在接口签名声明中写abstract（默认是public和abstract）！

方法的参数将/必须/是 - 也总是相同的！

实现类代码方法签名应该在接口上几乎完全一致，如果没有，完全一致。