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改造1.9如何从回调中启动新活动

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我只是提问，我认为很简单:)我无法从Retrofit中的CallBack方法启动新的Activity，我遇到的问题就像

" android.util.AndroidRuntimeException: Calling startActivity() from outside of an Activity context requires the FLAG_ACTIVITY_NEW_TASK flag. Is this really what you want?"

sign_in_button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            String userEmail = email.getText().toString();
            String userPassword = password.getText().toString();

            final LoginService loginService = RetrofitClient.createService(LoginService.class, userEmail, userPassword);
            loginService.basicLogin(new Callback<User>() {
                @Override
                public void success(User user, Response response) {
                    Toast.makeText(getApplicationContext(),"You are Logged", Toast.LENGTH_SHORT).show();

                    Intent intent = new Intent(getApplicationContext(), BetweenActivity.class);
                    startActivity(intent);





                }

                @Override
                public void failure(RetrofitError error) {
                    Toast.makeText(getApplicationContext(),"Something went wrong", Toast.LENGTH_SHORT).show();

                }
            });

这是我的日志：

致命异常：主要进程：com.example.bunzlau.retrofit，PID：18138 java.lang.RuntimeException：无法启动活动ComponentInfo {com.example.bunzlau.retrofit / com.example.bunzlau.retrofit.BetweenActivity}：java . lang.NullPointerException：尝试调用虚拟方法“android.view.View android.widget.Button.findViewById（INT）”上在android.app.ActivityThread.performLaunchActivity（ActivityThread.java:3253）空对象引用在android.app .ActivityThread.handleLaunchActivity（ActivityThread.java:3349）在android.app.ActivityThread.access $ 1100（ActivityThread.java:221）在android.app.ActivityThread $ H.handleMessage（ActivityThread.java:1794）在android.os.Handler .dispatchMessage（Handler.java:102）位于android.app.Looper.loop（Looper.java:158）的android.app.ActivityThread.main（ActivityThread.java:7225），位于java.lang.reflect.Method.invoke（本地方法）com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:1230）at com.android.internal.os.ZygoteInit.main（Zy） goteInit.java:1120）引起：java.lang.NullPointerException：尝试在com.example.bunzlau.retrofit上的空对象引用上调用虚方法'android.view.View android.widget.Button.findViewById（int）' .BetweenActivity.onCreate（BetweenActivity.java:18）在android.app.Activity.performCreate（Activity.java:6876）在android.app.Instrumentation.callActivityOnCreate（Instrumentation.java:1135）在android.app.ActivityThread.performLaunchActivity（ ActivityThread.java:3206）在android.app.ActivityThread.handleLaunchActivity（ActivityThread.java:3349）在android.app.ActivityThread.access $ 1100（ActivityThread.java:221）在android.app.ActivityThread $ H.handleMessage（ActivityThread . java：1794）在android.os.Handler.dispatchMessage（Handler.java:102）的android.app.Looper.loop（Looper.java:158）android.app.ActivityThread.main（ActivityThread.java:7225）at java.lang.reflect.Method.invoke（Native Method）位于com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:1230）的com.and roid.internal.os.ZygoteInit.main（ZygoteInit.java:1120）

java android callback retrofit

1 回答

  • 0

    您从Callback范围内调用startActivity（），而不是活动范围 . 您需要获取当前活动的引用，并使用它来启动下一个活动 .

    private Context context = this;

sign_in_button.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View view) {
        String userEmail = email.getText().toString();
        String userPassword = password.getText().toString();

        final LoginService loginService = RetrofitClient.createService(LoginService.class, userEmail, userPassword);
        loginService.basicLogin(new Callback<User>() {
            @Override
            public void success(User user, Response response) {
                Toast.makeText(getApplicationContext(),"You are Logged", Toast.LENGTH_SHORT).show();

                Intent intent = new Intent(getApplicationContext(), BetweenActivity.class);
                context.startActivity(intent);





            }

            @Override
            public void failure(RetrofitError error) {
                Toast.makeText(getApplicationContext(),"Something went wrong", Toast.LENGTH_SHORT).show();

            }
        });
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