[英]How to modify string returned from super function
這是我在超類中的toString()函數。 我希望能夠在子類中重用此函數,但將其修改為改為“梯形坐標”而不是“四邊形坐標”。
我嘗試使用stringbuilder修改返回值,但是它沒有用,所以也許我濫用了stringbuilder。 我想做些什么嗎?還是應該將整個方法的代碼復制/粘貼到我的子類方法中,然后在那里修改文本?
public String toString(){ //this function returns a readable view of our quadrilateral object
String message = new String();
message = "Coordinates of Quadrilateral are:\n< " + this.point1.getX() + ", " + this.point1.getY() + " >, < "
+ this.point2.getX() + ", " + this.point2.getY() + " >, < "
+ this.point3.getX() + ", " + this.point3.getY() + " >, < "
+ this.point4.getX() + ", " + this.point4.getY() + " >\n";
return message;
}
這是我的子類
//this function returns a readable view of our trapezoid
public String toString(){
String modify = super.toString();
StringBuilder sb = new StringBuilder(modify);
sb.replace(16, 28, "Trapezoid");
return modify + "\nHeight is: " + getHeight() + "\nArea is: " + getArea();
}
代替
return modify + "\\nHeight is: " + getHeight() + "\\nArea is: " + getArea();
嘗試
return sb.toString() + "\nHeight is: " + getHeight() + "\nArea is: " + getArea();
順便說一句,而不是+
,最好使用StringBuilder.append()
,像這樣
String modify = super.toString();
StringBuilder sb = new StringBuilder(modify);
sb.replace(16, 28, "Trapezoid");
sb.append("\nHeight is: ").append(getHeight()); // etc.
比修改超類的輸出更好的是修改超類,以便子類可以提供適當的形狀名稱,例如
class Quadrilateral {
protected String getShapeName() {
return "Quadrilateral";
}
public String toString() {
String message = "Coordinates of " + getShapeName() + ...
...
}
}
class Trapezoid {
@Override
protected String getShapeName() {
return "Trapezoid";
}
}
主要好處是您擺脫了梯形的toString()對超類toString()確切措辭的依賴。 假設您將四邊形的toString()消息更改為“四邊形的坐標...”-如果這樣做,則必須修改梯形(以及其他子類)中的索引(16、28)或它的toString( )將顯示“ thelinesTrapezoideral ...”
采用
return sb.toString() + "\nHeight is: " + getHeight() + "\nArea is: " + getArea();
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.