[英]How do I override an attribute from a super class in a subclass?
我很確定我的代碼應該可以正常工作,但是我的學習平台中的測試失敗,說明我的子類中的構造函數“應該將描述設置為‘未分類’以外的值”
Parent Class
public class Rock
{
int sampleNumber;
String description;
double weight;
public Rock(int sampleNumber, double weight)
{
this.sampleNumber = sampleNumber;
this.description = "Unclassified";
this.weight = weight;
}
public void setSampleNumber( int sampleNumber ){
this.sampleNumber = sampleNumber;
}
public int getSampleNumber(){
return this.sampleNumber;
}
public void setDescription( String description ){
this.description = description;
}
public String getDescription(){
return this.description;
}
public void setWeight(double weight){
this.weight = weight;
}
public double getWeight() {
return this.weight;
}
public String toString()
{
return "The number of samples are: "+sampleNumber+
"\nThe weight of the rock is: "+ weight+
"\nThe description of rock type is: "+ description;
}
}
子類之一(有 3 個,它們幾乎相同)
public class SedimentaryRock extends Rock
{
public SedimentaryRock(int sampleNumber,int weight)
{
super(sampleNumber, weight);
}
public void setDescription( String description ){
super.description = description;
}
public String getDescription(){
return super.description;
}
}
這是主類
public class DemoRocks
{
public static void main(String[] args)
{
IgneousRock rock = new IgneousRock( 2, 200);
rock.setDescription("andesite");
System.out.println(rock.toString());
SedimentaryRock rock2= new SedimentaryRock( 3, 300);
rock2.setDescription("sandstone");
System.out.println(rock2.toString());
MetamorphicRock rock3=new MetamorphicRock( 4, 400);
rock3.setDescription("quartzite");
System.out.println(rock3.toString());
}
}
輸出是:
The number of samples are: 2
The weight of the rock is: 200.0
The description of rock type is: andesite
The number of samples are: 3
The weight of the rock is: 300.0
The description of rock type is: sandstone
The number of samples are: 4
The weight of the rock is: 400.0
The description of rock type is: quartzite
避免該問題的一種方法是將父類中的描述設置為“ ”而不是“未分類”,但需要將其設置為“未分類”。
我不知道是什么導致它的行為如此。
我懷疑測試希望你在下面做:
public SedimentaryRock(int sampleNumber,int weight) {
super(sampleNumber, weight);
super.setDescription("sedimentary");
}
我假設測試希望您覆蓋構造函數本身中的屬性而不是顯式設置它
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