Java 无法从“活动”到“片段”获取字符串。请看详情

我已经经历了很多问题，虽然这个问题似乎是重复的，但它不是

我想将2个字符串从一个活动传递到一个片段，但未能传递到以下错误：

java.lang.NullPointerException:尝试调用虚拟方法'java.lang.String android.os.Bundle.getString（java.lang.String）'在com.abc.xyz.PostARequest$2$2.run（PostARequest.java:154）上的空对象引用上

下面是
PostARequest.java
（片段）文件的代码：

public class PostARequest extends Fragment {

    Bitmap bitmap;
    ImageView hPic;
    boolean hasDrawable;
    EditText hsDescription;
    TextView hPicTag, hLocationTag, currentCoordinatesTag, currentLat, currentLng;
    LinearLayout latContainer, lngContainer;
    Bundle b;
    TabHost tabHost;
    String latitude, longitude;

    private OnFragmentInteractionListener mListener;

    public PostARequest() {
        // Required empty public constructor
    }

    /**
     * Use this factory method to create a new instance of
     * this fragment using the provided parameters.
     *
     * @param param1 Parameter 1.
     * @param param2 Parameter 2.
     * @return A new instance of fragment PostARequest.
     */
    // TODO: Rename and change types and number of parameters
    public static PostARequest newInstance(String param1, String param2) {
        PostARequest fragment = new PostARequest();
        Bundle args = new Bundle();
        args.putString(ARG_PARAM1, param1);
        args.putString(ARG_PARAM2, param2);
        fragment.setArguments(args);
        return fragment;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (getArguments() != null) {
            mParam1 = getArguments().getString(ARG_PARAM1);
            mParam2 = getArguments().getString(ARG_PARAM2);
        }
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View rootView = inflater.inflate(R.layout.fragment_post_a_request, container, false);

        // check for location here

        currentCoordinatesTag = (TextView) rootView.findViewById(R.id.currentCoordinatesTag);
        latContainer = (LinearLayout) rootView.findViewById(R.id.latContainer);
        currentLat = (TextView) rootView.findViewById(R.id.currentLat);
        lngContainer = (LinearLayout) rootView.findViewById(R.id.lngContainer);
        currentLng = (TextView) rootView.findViewById(R.id.currentLng);

        currentCoordinatesTag.setVisibility(View.INVISIBLE);
        latContainer.setVisibility(View.INVISIBLE);
        currentLat.setVisibility(View.INVISIBLE);
        lngContainer.setVisibility(View.INVISIBLE);
        currentLng.setVisibility(View.INVISIBLE);

        tabHost = new TabHost(getContext());

        b = this.getArguments();

        hLocationTag = (TextView) rootView.findViewById(R.id.h_location_tag);
        hLocationTag.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent mapsIntent = new Intent(getContext(), MapsActivity.class);
                startActivity(mapsIntent);
                final Handler handler = new Handler();
                handler.postDelayed(new Runnable() {
                    @Override
                    public void run() {
                        homelessLocationTag.setVisibility(View.INVISIBLE);
                    }
                }, 500);

                final Handler handler2 = new Handler();
                handler2.postDelayed(new Runnable() {
                    @Override
                    public void run() {

                        currentCoordinatesTag.setVisibility(View.VISIBLE);
                        latContainer.setVisibility(View.VISIBLE);
                        currentLat.setVisibility(View.VISIBLE);
                        lngContainer.setVisibility(View.VISIBLE);
                        currentLng.setVisibility(View.VISIBLE);

                        latitude = b.getString("latitude");
                        longitude = b.getString("longitude");

                        currentLat.setText(latitude);
                        currentLng.setText(longitude);

                        tabHost.setCurrentTab(2);

                    }
                }, 15000);

            }
        });
}

public class MapsActivity extends FragmentActivity implements OnMapReadyCallback {

    private GoogleMap mMap;
    FloatingActionButton addLocationFab;
    Double latitude, longitude;
    LatLng userCurrentPosition;
    String coordl1, coordl2;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_maps);
        // Obtain the SupportMapFragment and get notified when the map is ready to be used.
        SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
                .findFragmentById(R.id.map);
        mapFragment.getMapAsync(this);

        addLocationFab = (FloatingActionButton) findViewById(R.id.addLocationFAB);

    }

    /**
     * Manipulates the map once available.
     * This callback is triggered when the map is ready to be used.
     * This is where we can add markers or lines, add listeners or move the camera. In this case,
     * we just add a marker near Sydney, Australia.
     * If Google Play services is not installed on the device, the user will be prompted to install
     * it inside the SupportMapFragment. This method will only be triggered once the user has
     * installed Google Play services and returned to the app.
     */
    @Override
    public void onMapReady(final GoogleMap googleMap) {
        mMap = googleMap;

        googleMap.setMyLocationEnabled(true);

        addLocationFab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                latitude = googleMap.getMyLocation().getLatitude();
                longitude = googleMap.getMyLocation().getLongitude();

                coordl1 = latitude.toString();
                coordl2 = longitude.toString();

                Log.d("latitude", coordl1);
                Log.d("longitude", coordl2);

                final Handler handler = new Handler();
                handler.postDelayed(new Runnable() {
                    @Override
                    public void run() {
                        Bundle bundle = new Bundle();
                        bundle.putString("latitude", coordl1);
                        bundle.putString("longitude", coordl2);
                        PostARequest postARequest = new PostARequest();
                        postARequest.setArguments(bundle);
                    }
                }, 5000);
            }
        });

    }

}

下面是
MapsaActivity.java
（活动）文件的代码：

public class PostARequest extends Fragment {

    Bitmap bitmap;
    ImageView hPic;
    boolean hasDrawable;
    EditText hsDescription;
    TextView hPicTag, hLocationTag, currentCoordinatesTag, currentLat, currentLng;
    LinearLayout latContainer, lngContainer;
    Bundle b;
    TabHost tabHost;
    String latitude, longitude;

    private OnFragmentInteractionListener mListener;

    public PostARequest() {
        // Required empty public constructor
    }

    /**
     * Use this factory method to create a new instance of
     * this fragment using the provided parameters.
     *
     * @param param1 Parameter 1.
     * @param param2 Parameter 2.
     * @return A new instance of fragment PostARequest.
     */
    // TODO: Rename and change types and number of parameters
    public static PostARequest newInstance(String param1, String param2) {
        PostARequest fragment = new PostARequest();
        Bundle args = new Bundle();
        args.putString(ARG_PARAM1, param1);
        args.putString(ARG_PARAM2, param2);
        fragment.setArguments(args);
        return fragment;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (getArguments() != null) {
            mParam1 = getArguments().getString(ARG_PARAM1);
            mParam2 = getArguments().getString(ARG_PARAM2);
        }
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View rootView = inflater.inflate(R.layout.fragment_post_a_request, container, false);

        // check for location here

        currentCoordinatesTag = (TextView) rootView.findViewById(R.id.currentCoordinatesTag);
        latContainer = (LinearLayout) rootView.findViewById(R.id.latContainer);
        currentLat = (TextView) rootView.findViewById(R.id.currentLat);
        lngContainer = (LinearLayout) rootView.findViewById(R.id.lngContainer);
        currentLng = (TextView) rootView.findViewById(R.id.currentLng);

        currentCoordinatesTag.setVisibility(View.INVISIBLE);
        latContainer.setVisibility(View.INVISIBLE);
        currentLat.setVisibility(View.INVISIBLE);
        lngContainer.setVisibility(View.INVISIBLE);
        currentLng.setVisibility(View.INVISIBLE);

        tabHost = new TabHost(getContext());

        b = this.getArguments();

        hLocationTag = (TextView) rootView.findViewById(R.id.h_location_tag);
        hLocationTag.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent mapsIntent = new Intent(getContext(), MapsActivity.class);
                startActivity(mapsIntent);
                final Handler handler = new Handler();
                handler.postDelayed(new Runnable() {
                    @Override
                    public void run() {
                        homelessLocationTag.setVisibility(View.INVISIBLE);
                    }
                }, 500);

                final Handler handler2 = new Handler();
                handler2.postDelayed(new Runnable() {
                    @Override
                    public void run() {

                        currentCoordinatesTag.setVisibility(View.VISIBLE);
                        latContainer.setVisibility(View.VISIBLE);
                        currentLat.setVisibility(View.VISIBLE);
                        lngContainer.setVisibility(View.VISIBLE);
                        currentLng.setVisibility(View.VISIBLE);

                        latitude = b.getString("latitude");
                        longitude = b.getString("longitude");

                        currentLat.setText(latitude);
                        currentLng.setText(longitude);

                        tabHost.setCurrentTab(2);

                    }
                }, 15000);

            }
        });
}

public class MapsActivity extends FragmentActivity implements OnMapReadyCallback {

    private GoogleMap mMap;
    FloatingActionButton addLocationFab;
    Double latitude, longitude;
    LatLng userCurrentPosition;
    String coordl1, coordl2;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_maps);
        // Obtain the SupportMapFragment and get notified when the map is ready to be used.
        SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
                .findFragmentById(R.id.map);
        mapFragment.getMapAsync(this);

        addLocationFab = (FloatingActionButton) findViewById(R.id.addLocationFAB);

    }

    /**
     * Manipulates the map once available.
     * This callback is triggered when the map is ready to be used.
     * This is where we can add markers or lines, add listeners or move the camera. In this case,
     * we just add a marker near Sydney, Australia.
     * If Google Play services is not installed on the device, the user will be prompted to install
     * it inside the SupportMapFragment. This method will only be triggered once the user has
     * installed Google Play services and returned to the app.
     */
    @Override
    public void onMapReady(final GoogleMap googleMap) {
        mMap = googleMap;

        googleMap.setMyLocationEnabled(true);

        addLocationFab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                latitude = googleMap.getMyLocation().getLatitude();
                longitude = googleMap.getMyLocation().getLongitude();

                coordl1 = latitude.toString();
                coordl2 = longitude.toString();

                Log.d("latitude", coordl1);
                Log.d("longitude", coordl2);

                final Handler handler = new Handler();
                handler.postDelayed(new Runnable() {
                    @Override
                    public void run() {
                        Bundle bundle = new Bundle();
                        bundle.putString("latitude", coordl1);
                        bundle.putString("longitude", coordl2);
                        PostARequest postARequest = new PostARequest();
                        postARequest.setArguments(bundle);
                    }
                }, 5000);
            }
        });

    }

}

我真的不知道这里出了什么问题

请让我知道

若问题状态不好，请配合，我仍在学习发布好的问题。
您并没有在片段中调用newInstance（）

使用

在片段中设置这些全局变量：

this.latitude = latitude;
this.longitude = longitude;

尝试初始化字符串以将数据从活动传递到片段：将此代码放在任意位置Bundle=new Bundle（）；bundle.putString（“KEY_NAME1”、“Abrakadabra”）；bundle.putString（“KEY_NAME2”、“Kadabra”）；MyFragment MyFragment=新的MyFragment（）；setArguments（bundle）；然后在片段的onCreateView方法中添加此代码束args=getArguments（）；String stringdata1=args.getString（“KEY_NAME1”）；String stringdata2=args.getString（“KEY_NAME2”）；我注意到的一件事是，您试图通过bundle将数据发送到再次创建的相同片段。我必须做同样的一次，因为我必须销毁/删除片段的前一个实例，然后执行您所做的过程。在调用函数发送数据之前，只需删除片段。或者，如果您不想销毁该片段，则必须使用我上面回答的界面。@suku您能简单回答一下吗？描述整个过程，整个事情。如何在没有任何错误的情况下将字符串从活动获取到片段。请问，我应该在哪里加这个？