我在互联网上找到了以下代码。我认为类型转换存在问题 我试图解决其中一些问题，但仍有一些问题无法解决。
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
public class Cluster {
public List points;
public Point centroid;
public int id;
//Creates a new Cluster
public Cluster(int id) {
this.id = id;
this.points = new ArrayList();
this.centroid = null;
}
public List getPoints() {
return points;
}
public void addPoint(Point point) {
points.add(point);
}
public void setPoints(List points) {
this.points = points;
}
public Point getCentroid() {
return centroid;
}
public void setCentroid(Point centroid) {
this.centroid = centroid;
}
public int getId() {
return id;
}
public void clear() {
points.clear();
}
public void plotCluster() {
System.out.println("[Cluster: " + id+"]");
System.out.println("[Centroid: " + centroid + "]");
System.out.println("[Points: \n");
for(Point p : points) {
System.out.println(p);
}
System.out.println("]");
}
}
public class Point {
private double x = 0;
private double y = 0;
private int cluster_number = 0;
public Point(double x, double y)
{
this.setX(x);
this.setY(y);
}
public void setX(double x) {
this.x = x;
}
public double getX() {
return this.x;
}
public void setY(double y) {
this.y = y;
}
public double getY() {
return this.y;
}
public void setCluster(int n) {
this.cluster_number = n;
}
public int getCluster() {
return this.cluster_number;
}
//Calculates the distance between two points.
protected static double distance(Point p, Point centroid) {
return Math.sqrt(Math.pow((centroid.getY() - p.getY()), 2) + Math.pow((centroid.getX() - p.getX()), 2));
}
//Creates random point
protected static Point createRandomPoint(int min, int max) {
Random r = new Random();
double x = min + (max - min) * r.nextDouble();
double y = min + (max - min) * r.nextDouble();
return new Point(x,y);
}
protected static List createRandomPoints(int min, int max, int number) {
List points = new ArrayList(number);
for(int i = 0; i < number; i++) {
points.add(createRandomPoint(min,max));
}
return points;
}
public String toString() {
return "("+x+","+y+")";
}
}
public class KMeans {
//Number of Clusters. This metric should be related to the number of points
private int NUM_CLUSTERS = 3;
//Number of Points
private int NUM_POINTS = 15;
//Min and Max X and Y
private static final int MIN_COORDINATE = 0;
private static final int MAX_COORDINATE = 10;
private List points;
private List clusters;
public KMeans() {
this.points = new ArrayList();
this.clusters = new ArrayList();
}
public static void main(String[] args) {
KMeans kmeans = new KMeans();
kmeans.init();
kmeans.calculate();
}
//Initializes the process
public void init() {
//Create Points
points = Point.createRandomPoints(MIN_COORDINATE,MAX_COORDINATE,NUM_POINTS);
//Create Clusters
//Set Random Centroids
for (int i = 0; i < NUM_CLUSTERS; i++) {
Cluster cluster = new Cluster(i);
Point centroid = Point.createRandomPoint(MIN_COORDINATE,MAX_COORDINATE);
cluster.setCentroid(centroid);
clusters.add(cluster);
}
//Print Initial state
plotClusters();
}
private void plotClusters() {
for (int i = 0; i < NUM_CLUSTERS; i++) {
Cluster c = clusters.get(i);
c.plotCluster();
}
}
//The process to calculate the K Means, with iterating method.
public void calculate() {
boolean finish = false;
int iteration = 0;
// Add in new data, one at a time, recalculating centroids with each new one.
while(!finish) {
//Clear cluster state
clearClusters();
List lastCentroids = getCentroids();
//Assign points to the closer cluster
assignCluster();
//Calculate new centroids.
calculateCentroids();
iteration++;
List currentCentroids = getCentroids();
//Calculates total distance between new and old Centroids
double distance = 0;
for(int i = 0; i < lastCentroids.size(); i++) {
distance += Point.distance(lastCentroids.get(i),currentCentroids.get(i));
}
System.out.println("#################");
System.out.println("Iteration: " + iteration);
System.out.println("Centroid distances: " + distance);
plotClusters();
if(distance == 0) {
finish = true;
}
}
}
private void clearClusters() {
for(Cluster cluster : clusters) {
cluster.clear();
}
}
private List getCentroids() {
List centroids = new ArrayList(NUM_CLUSTERS);
for(Cluster cluster : clusters) {
Point aux = cluster.getCentroid();
Point point = new Point(aux.getX(),aux.getY());
centroids.add(point);
}
return centroids;
}
private void assignCluster() {
double max = Double.MAX_VALUE;
double min = max;
int cluster = 0;
double distance = 0.0;
for(Point point : points) {
min = max;
for(int i = 0; i < NUM_CLUSTERS; i++) {
Cluster c = clusters.get(i);
distance = Point.distance(point, c.getCentroid());
if(distance < min){
min = distance;
cluster = i;
}
}
point.setCluster(cluster);
clusters.get(cluster).addPoint(point);
}
}
private void calculateCentroids() {
for(Cluster cluster : clusters) {
double sumX = 0;
double sumY = 0;
List list = cluster.getPoints();
int n_points = list.size();
for(Point point : list) {
sumX += point.getX();
sumY += point.getY();
}
Point centroid = cluster.getCentroid();
if(n_points > 0) {
double newX = sumX / n_points;
double newY = sumY / n_points;
centroid.setX(newX);
centroid.setY(newY);
}
}
}
}
我得到了以下错误。如何解决它们：
java:45: warning: [unchecked] unchecked call to add(E) as a member of the raw type List
clusters.add(cluster);
^
where E is a type-variable:
E extends Object declared in interface List
/tmp/java_kmNqUn/KMeans.java:54: error: incompatible types: Object cannot be converted to Cluster
Cluster c = clusters.get(i);
^
/tmp/java_kmNqUn/KMeans.java:84: error: incompatible types: Object cannot be converted to Point
distance += Point.distance(lastCentroids.get(i),currentCentroids.get(i));
^
/tmp/java_kmNqUn/KMeans.java:98: error: incompatible types: Object cannot be converted to Cluster
for(Cluster cluster : clusters) {
^
/tmp/java_kmNqUn/KMeans.java:105: error: incompatible types: Object cannot be converted to Cluster
for(Cluster cluster : clusters) {
^
/tmp/java_kmNqUn/KMeans.java:108: warning: [unchecked] unchecked call to add(E) as a member of the raw type List
centroids.add(point);
^
where E is a type-variable:
E extends Object declared in interface List
/tmp/java_kmNqUn/KMeans.java:119: error: incompatible types: Object cannot be converted to Point
for(Point point : points) {
^
/tmp/java_kmNqUn/KMeans.java:122: error: incompatible types: Object cannot be converted to Cluster
Cluster c = clusters.get(i);
^
/tmp/java_kmNqUn/KMeans.java:130: error: cannot find symbol
clusters.get(cluster).addPoint(point);
^
symbol: method addPoint(Point)
location: class Object
/tmp/java_kmNqUn/KMeans.java:135: error: incompatible types: Object cannot be converted to Cluster
for(Cluster cluster : clusters) {
^
/tmp/java_kmNqUn/KMeans.java:141: error: incompatible types: Object cannot be converted to Point
for(Point point : list) {
^
/tmp/java_kmNqUn/Point.java:61: warning: [unchecked] unchecked call to add(E) as a member of the raw type List
points.add(createRandomPoint(min,max));
^
where E is a type-variable:
E extends Object declared in interface List
/tmp/java_kmNqUn/Cluster.java:27: warning: [unchecked] unchecked call to add(E) as a member of the raw type List
points.add(point);
^
where E is a type-variable:
E extends Object declared in interface List
/tmp/java_kmNqUn/Cluster.java:54: error: incompatible types: Object cannot be converted to Point
for(Point p : points) {
^
Note: Some messages have been simplified; recompile with -Xdiags:verbose to get full output
10 errors
4 warnings*
请指导我......
答案 0 :(得分：2)
您应该避免使用没有任何类型参数的类型List。您应该使用List<SomeType>（将SomeType替换为相关类型）。
答案 1 :(得分：0)
使用带有类型参数的强类型泛型List是执行此操作的最佳方式。但是，如果您被迫使用不支持泛型的旧版Java，则可以像这样强制转换集群对象：Cluster c = (Cluster)clusters.get(i);