Working on a Java application I am finding the following problem related to inheritance.
I have the following situation:
1) I defined an abstract class named TrendFromExcelAbstract. This class contains some basic fields common to other classes which extend it and represent different tabs of an Excel file (but this is not important now):
public abstract class TrendFromExcelAbstract {
private Long id;
private String date;
private String time;
private String excelDocumentName;
private String excelDocumentSheet;
public TrendFromExcelAbstract() {
super();
}
public TrendFromExcelAbstract(Long id, String date, String time, String excelDocumentName,
String excelDocumentSheet) {
super();
this.id = id;
this.date = date;
this.time = time;
this.excelDocumentName = excelDocumentName;
this.excelDocumentSheet = excelDocumentSheet;
}
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GETTER AND SETTER METHODS
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}
Then I have a class named CompVibrAndTempDTO extending the previous abstract class:
public class CompVibrAndTempDTO extends TrendFromExcelAbstract {
// Temperature reading point
private String tempReadingPointA;
private String tempReadingPointB;
private String tempReadingPointC;
private String tempReadingPointD;
private String tempReadingPointE;
private String tempReadingPointF;
private String tempReadingPointG;
private String tempReadingPointH;
private String tempReadingPointI;
private String tempReadingPointJ;
private String tempReadingPointK;
private String tempReadingPointL;
private String tempReadingPointM;
private String tempReadingPointN;
private String tempReadingPointO;
private String tempReadingPointP;
// Vibration reading point
private String vibrReadingPointA;
private String vibrReadingPointB;
private String vibrReadingPointC;
private String vibrReadingPointD;
private String vibrReadingPointE;
private String vibrReadingPointF;
private String vibrReadingPointG;
private String vibrReadingPointH;
private String vibrReadingPointI;
private String vibrReadingPointJ;
private String vibrReadingPointK;
private String vibrReadingPointL;
public CompVibrAndTempDTO() {
super();
}
public CompVibrAndTempDTO(Long id, String date, String time, String excelDocumentName, String excelDocumentSheet,
String tempReadingPointA, String tempReadingPointB, String tempReadingPointC, String tempReadingPointD,
String tempReadingPointE, String tempReadingPointF, String tempReadingPointG, String tempReadingPointH,
String tempReadingPointI, String tempReadingPointJ, String tempReadingPointK, String tempReadingPointL,
String tempReadingPointM, String tempReadingPointN, String tempReadingPointO, String tempReadingPointP,
String vibrReadingPointA, String vibrReadingPointB, String vibrReadingPointC, String vibrReadingPointD,
String vibrReadingPointE, String vibrReadingPointF, String vibrReadingPointG, String vibrReadingPointH,
String vibrReadingPointI, String vibrReadingPointJ, String vibrReadingPointK, String vibrReadingPointL) {
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}
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GETTER AND SETTER METHODS
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}
Then I have another DTO class named ExcelTabGeneralInfoDTO like this:
public class ExcelTabGeneralInfoDTO {
private String excelDocumentName;
private String excelSheetName;
private List<TrendFromExcelAbstract> trendOfTabList;
public ExcelTabGeneralInfoDTO() {
super();
}
public ExcelTabGeneralInfoDTO(String excelDocumentName, String excelSheetName,
List<TrendFromExcelAbstract> trendOfTabList) {
super();
this.excelDocumentName = excelDocumentName;
this.excelSheetName = excelSheetName;
this.trendOfTabList = trendOfTabList;
}
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GETTER AND SETTER METHODS
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}
As you can see this class contains this list field:
private List<TrendFromExcelAbstract> trendOfTabList;
The idea is that this field represents a list of any objects that derive from TrendFromExcelAbstract
The problem is that in another class I am trying to do something like this:
public List<ExcelTabGeneralInfoDTO> getCompVibrAndTempTab() {
List<CompVibrAndTempDTO> tabTrendList = excelRepo.findCompVibrAndTempTab();
String excelDocumentName;
String excelSheetName;
if(tabTrendList.size() >=0 ) {
excelDocumentName = tabTrendList.get(0).getExcelDocumentName();
excelSheetName = tabTrendList.get(0).getExcelDocumentSheet();
}
ExcelTabGeneralInfoDTO result = new ExcelTabGeneralInfoDTO(excelDocumentName, excelSheetName, tabTrendList);
return result;
}
So basically at this line:
ExcelTabGeneralInfoDTO result = new ExcelTabGeneralInfoDTO(excelDocumentName, excelSheetName, tabTrendList);
I am trying to create a new ExcelTabGeneralInfoDTO, passing to it the tabTrendList list having type List.
I get the following error message:
Description Resource Path Location Type
The constructor ExcelTabGeneralInfoDTO(String, String, List<CompVibrAndTempDTO>) is undefined ExcelServiceImpl.java /energy-prg-be/src/main/java/com/springboot/excelapi/services line 425 Java Problem
Description Resource Path Location Type
Type mismatch: cannot convert from List<ExcelTabGeneralInfoDTO> to List<CompVibrAndTempDTO> ExcelResource.java /energy-prg-be/src/main/java/com/springboot/excelapi/resources line 167 Java Problem
My idea is that I can use the more general type (ExcelTabGeneralInfoDTO) and then pass the child type (CompVibrAndTempDTO). But it seems that my assumption is false. What is wrong? What am I missing? Why can't I do something like this? How can I fix it?
