如何解决Retrofit2接口空指针

Question

我尝试连接我的服务器，但在这里停留了大约 3 个小时。只需在另一个项目中使用它，但是......无论如何，这是我的接口和服务生成器。请帮帮我...

服务生成器

import retrofit2.Retrofit;
import retrofit2.converter.gson.GsonConverterFactory;


public class ServiceGenerator {
 private ServiceInterface serviceInterface;
 private String BASE_URL = "http://xxxxxxxxx.com/xxxxx/xxx/";

 public ServiceInterface init() {

          Retrofit retrofit = new Retrofit.Builder()
                 .addConverterFactory(GsonConverterFactory.create())
                 .baseUrl(BASE_URL)
                 .build();
         serviceInterface = retrofit.create(ServiceInterface.class);

     return serviceInterface;
 }

 public ServiceInterface getServiceInterface() {
     return serviceInterface;
 }

}

服务接口

import retrofit2.Call;
import retrofit2.http.GET;
import retrofit2.http.Query;


public interface ServiceInterface {

  @GET("login.php")
  Call<LoginResponse> login(@Query("UserName") String id,
                            @Query("Password") String pass,
                            @Query("token") String token
  );  


 }

xxxxxxApp

import android.app.Application;

    import com.xxxxxxxxxxxxx.network.ServiceGenerator;
    import com.xxxxxxxxxxxxx.network.ServiceInterface;

    public class xxxxxxApp extends Application {
    private static xxxxxxApp instance;
    private ServiceGenerator serviceGenerator = new ServiceGenerator();

    public static xxxxxxApp getInstance() {
        return instance;
    }

    @Override
    public void onCreate() {
        super.onCreate();
        instance = this;
        serviceGenerator.init();

    }

    public ServiceInterface getServiceInterface() {
    return serviceGenerator.getServiceInterface();
    }



}

LoginAct.java

public class LoginAct extends BaseActivity {

SharedPreferences preferences;

Button btn_login;
EditText edt_username;
EditText edt_pass;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.act_login);

    btn_login = findViewById(R.id.login_btn_login);
    edt_username = findViewById(R.id.lgn_et_username);
    edt_pass = findViewById(R.id.lgn_et_pass);

    btn_login.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            xxxxxxApp.getInstance().getServiceInterface().login(edt_username.getText().toString(),edt_pass.getText().toString(),"").enqueue(new Callback<LoginResponse>() {
                @Override
                public void onResponse(Call<LoginResponse> call, Response<LoginResponse> response) {
                    if (response.isSuccessful()){
                        LoginAct.super.showToast(LoginAct.this," UserID : "+response.body().getUsers().get(0).getUser_ıd());
                    }
                }

                @Override
                public void onFailure(Call<LoginResponse> call, Throwable t) {

                }
            });
        }
    });

}
}

如果你喜欢我的网址没有 SSL 它的 http:// 。我的错误说：

java.lang.NullPointerException: Attempt to invoke virtual method 'com.xxxxxxxxxxxxxxxx.network.ServiceInterface com.xxxxxxxxxxxxxxxx.xxxxxxApp.getServiceInterface()' on a null object reference
    at com.xxxxxxxxxxxxxxxx.ui.LoginAct$1.onClick(LoginAct.java:40)

我不知道如何解决这个问题，我尽我所能。请帮忙。

。 . . . . . . .

Answer 1

将您的基本网址设置为

 private String BASE_URL = "http://xxxxxxxxx.com/xxxxx";

和接口进入

 @GET("/xxx/login.php")
  Call<LoginResponse> login(@Query("UserName") String id,
                            @Query("Password") String pass,
                            @Query("token") String token
  );