The constructor InputStreamReader(InputStreamReader) is undefined 这是什么问题？哪里错了？

import java.io.*;

public class Test7 {


public static void main(String[] args) {
// TODO Auto-generated method stub
Dog dogs[]=new Dog[4];
//从控制台输入狗的信息
InputStreamReader isr=new InputStreamReader(isr);
BufferedReader br=new BufferedReader(isr);
for(int i=0;i<4;i++){
dogs[i]=new Dog();
System.out.println("请输入第"+(i+1)+"狗的名字：");
//从控制台读取狗名
String name=br.readLine();
dogs[i].setName(name);
System.out.println("请输入第"+i+"狗的体重：");
String s_weight=br.readLine();
float weight=Float.parseFloat(s_weight);
dogs[i].setWeigh(weight);
}
//计算平均体重
float allWeight=0;
for(int i=0;i<4;i++){
allWeight+=dogs[i].getWeigh();
}
float avgWeight=allWeight=allWeight/dogs.length;
System.out.println("总重="+allWeight+"平均重="+avgWeight);
}

}
class Dog{
private String name;
private float weigh;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public float getWeigh() {
return weigh;
}
public void setWeigh(float weigh) {
this.weigh = weigh;
}

}

当你的代码：InputStreamReader isr=new InputStreamReader(isr);执行的时候，会访问InputStreamReader类。
InputStreamReader 是一个类（class）的名字。你应该只拿了部分代码。
InputStreamReader那部分你没有复制到或者不在一个文件夹里

支持一下感觉挺不错的