获取欧氏距离的 Java 方法
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Java methods getting euclidean distance
提问by user3444564
public class Point
{
// Placeholders for xcoordinate, ycoordinate, and quadrants
int xcoord = 0;
int ycoord =0;
double distance = 0.0;
String quadrant = ("NW");
//moveUp changes the y coordinate
void moveUp (int x) {
int moveUp = ycoord + x;
ycoord= moveUp;
System.out.println(moveUp);
}
// moveDown changes the y coordinate
void moveDown (int y){
int moveDown = ycoord - y;
ycoord =moveDown;
System.out.println(moveDown);}
// moveLeft changes the x coordinate
void moveLeft (int f){
int moveLeft = xcoord -f ;
xcoord = moveLeft;
System.out.println(moveLeft);}
// moveRight changes the x coordinate
void moveRight (int h) {
int moveRight = xcoord +h ;
xcoord = moveRight;
System.out.println(moveRight);}
// This takes the y coordinate and the xcoordinate and places it into a quadrant. Then it returns the quadrant.
String quadrant () {
if (xcoord >= 0 && ycoord >=0){
return quadrant = ("NE"); }
else if ( xcoord < 0 && ycoord < 0 ) {
return quadrant = ("SW");}
else if (xcoord <0 && ycoord >0 ){
return quadrant = ("NW");}
else if (xcoord >0 && ycoord <0){
return quadrant = ("SE");}
else {
return quadrant = ("Origin");}
}
//euclidean distance (?)
Point distance (Point other) {
Point result = new Point();
result.ycoord = Math.abs (ycoord - other.ycoord);
result.xcoord = Math.abs (xcoord- other.xcoord);
result.distance = Math.sqrt((result.ycoord)*(result.ycoord) +(result.xcoord)*(result.xcoord));
System.out.println(result);
return result;
}
}
Here is the whole code. What I'm having trouble with is for some reason my distance method isn't working properly and I don't know why. It returns Point@24a42c89, instead of any number. Please let me know why it is returning this instead of a number. Thanks so much. I'm a beginner and have little knowledge on Java.
这是整个代码。我遇到的问题是由于某种原因我的距离方法不能正常工作，我不知道为什么。它返回Point@24a42c89，而不是任何数字。请让我知道为什么它返回这个而不是一个数字。非常感谢。我是初学者，对Java知之甚少。
采纳答案by Daniel Ribeiro Moreira
Your method returns a Point because you return resultwhich is an instance of Point. If you want a double (value) for the distance you should do it this way:
您的方法返回一个 Point，因为您返回的result是 Point 的一个实例。如果你想要一个双倍（值）的距离，你应该这样做：
//euclidean distance (?)
double distance (Point other) {
Point result = new Point();
result.ycoord = Math.abs (ycoord - other.ycoord);
result.xcoord = Math.abs (xcoord- other.xcoord);
result.distance = Math.sqrt((result.ycoord)*(result.ycoord) +(result.xcoord)*(result.xcoord));
System.out.println(result);
return result.distance;
}
}
回答by Kick Buttowski
In you distance function
在你距离函数
Point distance (Point other) {
...
rest of your code
...
System.out.println(result); <-- you have tired to print out the object
return result;
}
to rectify your issue you need to print out the filed of the object that you are looking for which is distance
要纠正您的问题，您需要打印出您正在寻找的对象的字段 distance
System.out.println(result.distance);
One suggestion
一个建议
you can change return type distancefunction from Pointto int
您可以将返回类型distance函数从更改Point为int
why?
为什么？
Because return the object Pointdoes not represent the value of distance
因为返回的对象Point不代表距离的值
回答by Code-Apprentice
You are getting a Pointas a result because you are returning a Pointobject. There is no reason to declare a Pointobject when calculating the distance between two points. The results of all calculations here are numbers, so declare all variables as double:
你得到一个Point结果是因为你正在返回一个Point对象。Point在计算两点之间的距离时，没有理由声明一个对象。这里所有计算的结果都是数字，因此将所有变量声明为double：
double distance (Point other) {
double deltaX = ycoord - other.ycoord;
double deltaY = xcoord - other.xcoord;
double result = Math.sqrt(deltaX*deltaX + deltaY*deltaY);
return result;
}
Note there is no need for Math.abs()since squaring two numbers always results in a non-negative number.
请注意，没有必要，Math.abs()因为将两个数字平方总是导致非负数。
This also removes the need of storing a distancevalue in every point. This should make sense because a point is a pair of (x, y) coordinates, but does nothave an inherent distance. Rather "distance" is a relationship between two points.
这也消除了distance在每个点存储值的需要。这应该是有意义，因为一个点是一对（X，Y）坐标，但不具有内在的距离。相反，“距离”是两点之间的关系。
