如何在Java中将映射值转换为字符串

Question

我能够以这种格式打印我的输出,System.out.println(map.get("email"));//this is printing fine但是在将它分配到String变量后我无法打印相同的值.我试过:String email=(String) map.get("email"); System.out.println("Email--"+email);//But this is not printing
我如何将地图值转换为字符串？请帮我.

我的完整代码:

String url = "https://www.googleapis.com/oauth2/v1/userinfo?alt=json&access_token="
              + authResponse.accessToken; 
            final StringBuffer r = new StringBuffer(); 
            final URL u = new URL(url);
            final URLConnection uc = u.openConnection();
            final int end = 1000;
            InputStreamReader isr = null;
            BufferedReader br = null; 
            isr = new InputStreamReader(uc.getInputStream());
            br = new BufferedReader(isr);
            final int chk = 0; 
            String pat = "\"(.*)\": \"(.*)\",";
            Pattern pattern = Pattern.compile(pat);
            Matcher matcher = null;
            Map map = new HashMap();

            while ((url = br.readLine()) != null)
            {
                if ((chk >= 0) && ((chk < end))) {
                    matcher = pattern.matcher(url);
                    if(matcher.find()) {
                        map.put(matcher.group(1), matcher.group(2));
                    }
                    //r.append(url).append('\n');
                }
            }
              System.out.println(map.get("email")); 
              String email=(String) map.get("email"); 
              System.out.println(email);

Answer 1

在使用任何集合或Map时始终使用Generic类型,除非您使用的是旧版本的Java版本1.5.因此,将地图声明为: -

Map<String, String> map = new HashMap<String, String>();

然后你根本不需要类型转换.map.get("email")只会给你String输入结果.