Question

运行应用程序时，我收到错误消息“无法实例化活动ComponentInfo”，并且应用程序崩溃。代码与教程非常相似。我真的不知道如何解决此问题。关于这个问题，请您多加注意。有关用户登录和从Rails服务器检索令牌的代码。这是代码。

#Main Activity
    public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    Retrofit.Builder builder = new Retrofit.Builder()
            .baseUrl("https://teamdronex.com/")
            .addConverterFactory(GsonConverterFactory.create());

    Retrofit retrofit = builder.build();
    UserClient userClient = retrofit.create(UserClient.class);

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        findViewById(R.id.btn_login).setOnClickListener(this);
        findViewById(R.id.btn_secret).setOnClickListener(this);
    }
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.btn_login:
                login();
                break;
            case R.id.btn_secret:
                getSecret();
                break;
        }

    }

    private static String token;

    private void login() {
        Login login = new Login("johndoe@example.com", "aaaaaa");
        Call<User> call = userClient.login(login);

        call.enqueue(new Callback<User>() {
            @Override
            public void onResponse(Call<User> call, Response<User> response) {
                if (response.isSuccessful()) {
                    Toast.makeText(MainActivity.this, response.body().getToken(), Toast.LENGTH_SHORT).show();
                    token = response.body().getToken();
                } else {
                    Toast.makeText(MainActivity.this, "login not correct", Toast.LENGTH_SHORT).show();

                }
            }

            @Override
            public void onFailure(Call<User> call, Throwable t) {
                Toast.makeText(MainActivity.this, "error", Toast.LENGTH_SHORT).show();
            }
        });
    }

    private void getSecret() {
        Call<ResponseBody> call = userClient.getSecret(token);

        call.enqueue(new Callback<ResponseBody>() {
            @Override
            public void onResponse(Call<ResponseBody> call, Response<ResponseBody> response) {
                if (response.isSuccessful()) {
                    try {
                        Toast.makeText(MainActivity.this, response.body().string(), Toast.LENGTH_SHORT).show();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                } else {
                    Toast.makeText(MainActivity.this, "token is not correct", Toast.LENGTH_SHORT).show();

                }
            }

            @Override
            public void onFailure(Call<ResponseBody> call, Throwable t) {
                Toast.makeText(MainActivity.this, "error", Toast.LENGTH_SHORT).show();

            }
        });
    }


}

#UserClient

public abstract class UserClient {
@POST("sign_in")
abstract Call<User> login(@Body Login login);

@GET("secretinfo")
abstract Call<ResponseBody> getSecret(@Header("Authorization") String authToken);

}

#Manifest.xml
    <?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.login_retro">
    <uses-permission android:name="android.permission.INTERNET"></uses-permission>
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".Api.model.MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

#Logcat Error


at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2548)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
    at android.app.ActivityThread.-wrap12(ActivityThread.java)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
    at android.os.Handler.dispatchMessage(Handler.java:102)
    at android.os.Looper.loop(Looper.java:154)
    at android.app.ActivityThread.main(ActivityThread.java:6077)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)
 Caused by: java.lang.IllegalArgumentException: API declarations must be interfaces.
    at retrofit2.Utils.validateServiceInterface(Utils.java:309)
    at retrofit2.Retrofit.create(Retrofit.java:128)
    at com.example.login_retro.Api.model.MainActivity.<init>(MainActivity.java:27)
    at java.lang.Class.newInstance(Native Method)
    at android.app.Instrumentation.newActivity(Instrumentation.java:1078)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2538)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707) 
    at android.app.ActivityThread.-wrap12(ActivityThread.java) 
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460) 
    at android.os.Handler.dispatchMessage(Handler.java:102) 
    at android.os.Looper.loop(Looper.java:154) 
    at android.app.ActivityThread.main(ActivityThread.java:6077) 
    at java.lang.reflect.Method.invoke(Native Method) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)

Answer 1

问题：您必须在Java接口（而不是Java抽象类）中定义HTTP API。

解决方案：从{p>更改UserClient

public abstract class UserClient {

    @POST("sign_in")
    abstract Call<User> login(@Body Login login);

    @GET("secretinfo")
    abstract Call<ResponseBody> getSecret(@Header("Authorization") String authToken);
}

到

public interface UserClient {

    @POST("sign_in")
    Call<User> login(@Body Login login);

    @GET("secretinfo")
    Call<ResponseBody> getSecret(@Header("Authorization") String authToken);
}

无法实例化活动ComponentInfo（应用程序不断停止）

1 个答案: