高新技术之类加载器，出现空指针异常，求解 - 黑马程序员技术交流社区

import java.io.FileInputStream;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.Properties;
public class ReflectTest2 {
public static void main(String[] args)throws Exception {
InputStream ips = ReflectTest2.class.getClass().getClassLoader().getResourceAsStream("cn/itcast/day1/config.properties");
//这里为什么报NullPointerException？？？
Properties props = new Properties();
props.load(ips);
ips.close();
String className = props.getProperty("className");
Collection collections =(Collection) Class.forName(className).newInstance();
ReflectPoint pt1 = new ReflectPoint(3,3);
ReflectPoint pt2 = new ReflectPoint(5,5);
ReflectPoint pt3 = new ReflectPoint(3,3);
collections.add(pt1);
collections.add(pt2);
collections.add(pt3);
collections.add(pt1);
System.out.println(collections.size());
}
}
class ReflectPoint {
private int x;
public int y;
public int getX() {
return x;
}
public void setX(int x) {
this.x = x;
}
public int getY() {
return y;
}
public void setY(int y) {
this.y = y;
}
public ReflectPoint(int x, int y) {
super();
this.x = x;
this.y = y;
}
}

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ReflectTest2.class.getClass().getClassLoader().getResourceAsStream("cn/itcast/day1/config.properties");

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ReflectTest2.class.getClassLoader().getResourceAsStream("cn/itcast/day1/config.properties");

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