电子邮件验证导致应用程序崩溃

Question

am试图集成Quick Email Verification API以在用户输入真实电子邮件地址时对其进行验证。因此，请遵循其文档和示例代码。在我添加他们的验证代码段之前，我的应用程序运行良好。现在，在我按下注册按钮后，它就停止工作了。 编码是新手，我知道错误在哪里。帮助赞赏！ TIA！

这是我的btn_register代码：

btn_register.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            String username = et_username.getText().toString();
            String password = et_password.getText().toString();
            String confirm_password = et_cpassword.getText().toString();
            String email = et_email.getText().toString();
            String mobile = et_mobile.getText().toString();

            if (username.equals("") || password.equals("") || confirm_password.equals("") || 
 email.isEmpty() || mobile.isEmpty()) {
                Toast.makeText(getApplicationContext(), "Fields Required", 
 Toast.LENGTH_SHORT).show();
            } else if (!isValidEmail(et_email.getText().toString())) {
                Toast.makeText(getApplicationContext(), "Email is not valid", 
 Toast.LENGTH_SHORT).show();
            } else if (!password.equals(confirm_password)) {
                Toast.makeText(getApplicationContext(), "Password does not match", 
 Toast.LENGTH_SHORT).show();
            } else if (!isValidNumber(et_mobile.getText().toString())) {
                Toast.makeText(getApplicationContext(), "Input valid number", 
 Toast.LENGTH_SHORT).show();
            }
            Intent intent = new Intent(getApplicationContext(), MainActivity.class);
            startActivity(intent);
            Toast.makeText(getApplicationContext(), "User registered", Toast.LENGTH_SHORT).show();
            insertUser();
        }
        private boolean isValidEmail(String email) {
            try {
                new QevSingleAPI().http.sendGet();
            } catch (Exception e) {
                e.printStackTrace();
            }
        return Boolean.parseBoolean(email);
        }
        private boolean isValidNumber(String mobile) {
            return Patterns.PHONE.matcher(mobile).matches();
        }
    });
 }

这是Qev类：

public class QevSingleAPI extends Registration {
    QevSingleAPI http = new QevSingleAPI();

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_registration);
    try {
        http.sendGet();
    } catch (Exception e) {
        e.printStackTrace();
    }
}

 void sendGet() throws Exception {
    String API_KEY = "apiKey";
    String EMAIL = et_email.getText().toString();

    String url = "http://api.quickemailverification.com/v1/verify?email="+EMAIL+"&apikey="+API_KEY;

    URL obj = new URL(url);
    HttpURLConnection con = (HttpURLConnection) obj.openConnection();

    // optional default is GET
    con.setRequestMethod("GET");

    int responseCode = con.getResponseCode();
    System.out.println("\nSending 'GET' request to URL : " + url);
    System.out.println("Response Code : " + responseCode);

    BufferedReader in = new BufferedReader(
            new InputStreamReader(con.getInputStream()));
    String inputLine;
    StringBuilder response = new StringBuilder();

    while ((inputLine = in.readLine()) != null) {
        response.append(inputLine);
    }
    in.close();
    Toast.makeText(getApplicationContext(), response.toString(), Toast.LENGTH_SHORT).show();
}
}