import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Scanner;
import java.util.Map.Entry;
import java.util.Set;
public class TeachClass {
public static void main(String[] args) {
String[]pro={"tom,corejava","john,oracle","susan,oracle","jerry,jdbc","jim,unix","kevin,jsp","lucy,jsp"};
Map<String,String>map=new HashMap<String,String>();
for(String s:pro){
String[]v=s.split(",");
map.put(v[0],v[1]);
}
map.put("allen", "jdbc");
map.put("lucy", "corejava");
Set<Map.Entry<String, String>>set=map.entrySet();
for(Entry<String, String> i:set){
System.out.println(i);
}
Scanner s=new Scanner(System.in);
System.out.println("请输入课程");
String c=s.next();
Set<String>sset=map.keySet();
for(String i:sset){
if(map.containsValue(c)){
if(map.get(i).equals(c)){
System.out.println(i);
}
}else{
System.out.println("没有这门课");
}
}
}
}