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Java 如何修复膨胀类android.support.design.widget.BottomNavigationView的错误

java android xml

Java 如何修复膨胀类android.support.design.widget.BottomNavigationView的错误,java,android,xml,Java,Android,Xml,尝试使用BottomNavigationView启动活动时遇到异常 当onCreate（）时，我遇到了一个异常，它一直工作得很好，直到现在，它突然开始抛出异常，问题似乎出在BottomNavigationView上，我继续尝试删除每一行并运行代码以找出问题所在，所以当我删除第40行时：app:menu=“@menu/navigation”，它工作了，但是它抛出了另一个异常（如下所述），尽管这个特定的行对于视图来说是必不可少的 我在网上发现，如果在build.gradle中，实现（'com.and

尝试使用BottomNavigationView启动活动时遇到异常

当
onCreate（）
时，我遇到了一个异常，它一直工作得很好，直到现在，它突然开始抛出异常，问题似乎出在BottomNavigationView上，我继续尝试删除每一行并运行代码以找出问题所在，所以当我删除第40行时：
app:menu=“@menu/navigation”
，它工作了，但是它抛出了另一个异常（如下所述），尽管这个特定的行对于视图来说是必不可少的

我在网上发现，如果在build.gradle中，实现（
'com.android.support:design'
）和（
'com.android.support:appcompat-v7'
）应该是相同的版本，那么它们完全是相同的版本，但尽管android Studio向我显示了appcompat实现行的一个错误

MainAppActivity.java

package com.example.myapplication;

import android.Manifest;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.ServiceConnection;
import android.content.SharedPreferences;
import android.content.pm.PackageManager;
import android.location.Location;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.IBinder;
import android.support.annotation.NonNull;
import android.support.design.widget.BottomNavigationView;
import android.support.v4.app.ActivityCompat;
import android.support.v4.app.Fragment;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.MenuItem;
import android.view.View;
import android.widget.FrameLayout;
import android.widget.ProgressBar;
import android.widget.TextView;

import com.example.myapplication.Users.User;
import com.google.android.gms.location.FusedLocationProviderClient;
import com.google.android.gms.location.LocationCallback;
import com.google.android.gms.location.LocationRequest;
import com.google.android.gms.location.LocationResult;
import com.google.android.gms.location.LocationServices;
import com.google.firebase.firestore.GeoPoint;
import java.util.List;

public class MainAppActivity extends AppCompatActivity {

    public static final String TAG = "MainApp";
    public static final int REQUEST_CODE_LAST_LOCATION = 123;

    Fragment selectedFragment;
    private Activity mainActivity = this;
    private Location thisLocation;
    private LocationRequest locationRequest;
    private LocationCallback locationCallback;
    private boolean shouldStartLocationUpdates = false;
    private FusedLocationProviderClient fusedLocationProviderClient;
    private MyDBService myService;
    private MyDBService.MyLocalBinder binder;
    private Boolean isBound;
    private ServiceConnection serviceConnection;
    private ProgressBar progressBar;
    private TextView progressLbl;
    private List<User> nearbyUsers;
    private User currentUser;


    private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener = new BottomNavigationView.OnNavigationItemSelectedListener() {
        @Override
        public boolean onNavigationItemSelected(@NonNull MenuItem item) {
            FrameLayout mainFrame = findViewById(R.id.mainFrame);
            Bundle bundle = new Bundle();
            switch (item.getItemId()) {
                case R.id.nav_home:
                    mainActivity.setTitle(R.string.online);
                    selectedFragment = new OnlineFragment();
                    bundle.putBinder("binder", binder);
                    if(!shouldStartLocationUpdates){
                        startLocationUpdates();
                    }
                    break;
                case R.id.nav_chat:
                    mainActivity.setTitle(R.string.messages);
                    selectedFragment = new MessagesFragment();
                    bundle.putBinder("binder", binder);
                    if(shouldStartLocationUpdates){
                        stopLocationUpdates();
                    }
                    break;
                case R.id.nav_favs:
                    mainActivity.setTitle(R.string.favourites);
                    selectedFragment = new FavouritesFragment();
                    bundle.putBinder("binder", binder);
                    if(shouldStartLocationUpdates){
                        stopLocationUpdates();
                    }
                    break;
            }
            selectedFragment.setArguments(bundle);
            getSupportFragmentManager().beginTransaction().replace(R.id.mainFrame, selectedFragment).commit();
            return true;
        }
    };



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

        serviceConnection = new ServiceConnection() {
            @Override
            public void onServiceConnected(ComponentName name, IBinder service) {
                binder = (MyDBService.MyLocalBinder) service;
                myService = binder.getService();
                isBound = true;
            }

            @Override
            public void onServiceDisconnected(ComponentName name) {
                isBound = false;
            }
        };

        Intent intent = new Intent(MainAppActivity.this, MyDBService.class);
        bindService(intent, serviceConnection, Context.BIND_AUTO_CREATE);

        locationCallback = new LocationCallback(){

            @Override
            public void onLocationResult(LocationResult locationResult) {
                List<Location> locationList = locationResult.getLocations();
                if (locationList.size() > 0) {
                    //The last location in the list is the newest
                    Location location = locationList.get(locationList.size() - 1);
                    Log.i(TAG, "Location: " + location.getLatitude() + " " + location.getLongitude());
                    thisLocation = location;
                    SharedPreferences sharedPreferences = getSharedPreferences("user", MODE_PRIVATE);
                    String id = sharedPreferences.getString("firestore_uid_db", null);
                    sharedPreferences.edit().putString("location", thisLocation.getLatitude() + "," + thisLocation.getLongitude()).commit();

                }
                if (selectedFragment == null) {
                    selectedFragment = new OnlineFragment();
                    Bundle bundle = new Bundle();
                    bundle.putBinder("binder", binder);
                    selectedFragment.setArguments(bundle);
                    getSupportFragmentManager().beginTransaction().replace(R.id.mainFrame, selectedFragment).commit();
                }
            }
        };

        BottomNavigationView navigation = (BottomNavigationView) findViewById(R.id.navigation);
        progressBar = findViewById(R.id.progressBarFragments);
        progressLbl = findViewById(R.id.progressLbl);
        navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);

        fusedLocationProviderClient = LocationServices.getFusedLocationProviderClient(this);
        getLocation();



    }

    private void getLocation() {
        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED &&
                ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
            // TODO: Consider calling
            //    ActivityCompat#requestPermissions
            // here to request the missing permissions, and then overriding
            //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
            //                                          int[] grantResults)
            // to handle the case where the user grants the permission. See the documentation
            // for ActivityCompat#requestPermissions for more details.

            ActivityCompat.requestPermissions(this,
                    new String[]{
                            Manifest.permission.ACCESS_COARSE_LOCATION,
                            Manifest.permission.ACCESS_FINE_LOCATION
                    },
                    REQUEST_CODE_LAST_LOCATION);

        }else {
            createLocationRequest();
            startLocationUpdates();
            new UpdateDBField().execute(thisLocation);
        }
    }
    private void createLocationRequest() {
        if (locationRequest == null)
            locationRequest = LocationRequest.create();
        locationRequest.setInterval(5000);
        locationRequest.setFastestInterval(5000);
        locationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
    }
    @SuppressLint("MissingPermission")
    private void startLocationUpdates() {
        shouldStartLocationUpdates = true;
        fusedLocationProviderClient.requestLocationUpdates(locationRequest, locationCallback, null);
    }

    private void stopLocationUpdates() {
        shouldStartLocationUpdates = false;
        fusedLocationProviderClient.removeLocationUpdates(locationCallback);
    }

    @Override
    public void onPause() {
        super.onPause();
        stopLocationUpdates();
    }

    @Override
    public void onStop() {
        super.onStop();
        stopLocationUpdates();
        // Unbind from the service
        if (isBound) {
            unbindService(serviceConnection);
            isBound = false;
        }
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        stopLocationUpdates();
    }

    @Override
    public void onResume() {
        super.onResume();
        if (shouldStartLocationUpdates)
            startLocationUpdates();
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        if (requestCode == REQUEST_CODE_LAST_LOCATION) {
            if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                getLocation();
            }
        }
    }

    public class UpdateDBField extends AsyncTask<Location, Integer, Void>{

        @Override
        protected void onPreExecute() {
            progressBar.setVisibility(View.VISIBLE);
            progressLbl.setVisibility(View.VISIBLE);
        }

        @Override
        protected void onProgressUpdate(Integer... ints) {
            switch (ints[0]){
                case 1:
                    progressLbl.setText("Getting location updates...");
                    break;
                case 2:
                    progressLbl.setText("Preparing users' info...");
                    break;
                case 3:
                    progressLbl.setText("Preparing nearby users...");
                    break;
            }
        }

        @Override
        protected Void doInBackground(Location... locations) {
            publishProgress(1);
            Log.d(TAG, "doInBackground: published 1");
            updateLocationInDB(locations[0]);

            publishProgress(2);
            Log.d(TAG, "doInBackground: published 2");
            defineCurrentUser();

            publishProgress(3);
            Log.d(TAG, "doInBackground: published 3");
            defineNearbyUsers();
            return null;
        }

        private void updateLocationInDB(Location location1) {
            if(location1 == null){
                try {
                    Thread.sleep(5000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                updateLocationInDB(thisLocation);
            }else{
                myService.updateLocationFieldInUsersTokens("latlng", new GeoPoint(location1.getLatitude(), location1.getLongitude()));
            }
        }

        private void defineCurrentUser() {
            currentUser = myService.getCurrentUser();
            if(currentUser == null){
                try {
                    Thread.sleep(5000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                defineCurrentUser();
            }
        }

        private void defineNearbyUsers() {
            nearbyUsers = myService.getNearbyUsers();
            if(nearbyUsers == null){
                try {
                    Thread.sleep(5000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                defineNearbyUsers();
            }
        }

        @Override
        protected void onPostExecute(Void aVoid) {
            progressBar.setVisibility(View.GONE);
            progressLbl.setVisibility(View.GONE);
        }
    }


}
build.gradle（模块：应用程序）

显示错误

菜单/navigation.xml

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">

    <item
        android:id="@+id/nav_home"
        android:icon="@drawable/ic_online"
        android:title="@string/online" />

    <item
        android:id="@+id/nav_chat"
        android:icon="@drawable/ic_chat_light_24dp"
        android:title="@string/messages" />

    <item
        android:id="@+id/nav_favs"
        android:icon="@drawable/ic_star_light_24dp"
        android:title="@string/favourites" />

</menu>
我看到了。我认为您的问题在于
UpdateDBField
类的
onPreExecute（）
部分代码。可能是两个

progressBar.setVisibility(View.VISIBLE);
progressLbl.setVisibility(View.VISIBLE);
是空的。确保从xml设置了正确的视图id，以避免空指针异常

编辑：

检查代码的这一部分：

progressBar = findViewById(R.id.progressBarFragments);
progressLbl = findViewById(R.id.progressLbl);
根据
onCreate（）
方法，检查用于此活动的xml字段中是否存在
progressBarFragments
和
progressLbl
ID，该xml字段为
R.layout.activity\u main\u app
。

通过清理项目解决了问题

Android Studio toolbar>Build>Clean Project

尝试替换Build.gradle中具有相同版本的这些行这可能会解决您的问题

    implementation 'com.android.support:appcompat-v7:27.1.1'
    implementation 'com.android.support:design:27.1.1'
    implementation 'com.jakewharton:butterknife:8.8.1'
    implementation 'com.android.support:support-v4:27.1.1'
Null与
MainAppActivity
的
getLocation（）
方法相关，在该方法中，在未初始化的文本视图上调用
setVisibility（）
，可以显示
MainAppActivity
code吗？@MetaSnarf将其添加到上述描述中，感谢您添加了答案。
progressLbl
每次返回Null，毫无理由，它在.xml和.java中都声明正确，请看我刚刚更新的xml代码。是的，这很奇怪。让我彻底检查一下，我们可能遗漏了一些琐碎的东西，您可以尝试在其他属性（如高度、宽度等）没有改变任何内容之前，先将id属性放在xml上吗 
E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.myapplication, PID: 21765
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.myapplication/com.example.myapplication.MainAppActivity}: android.view.InflateException: Binary XML file line #32: Binary XML file line #32: Error inflating class android.support.design.widget.BottomNavigationView
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2913)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3048)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1808)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:193)
        at android.app.ActivityThread.main(ActivityThread.java:6669)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
     Caused by: android.view.InflateException: Binary XML file line #32: Binary XML file line #32: Error inflating class android.support.design.widget.BottomNavigationView
     Caused by: android.view.InflateException: Binary XML file line #32: Error inflating class android.support.design.widget.BottomNavigationView
     Caused by: java.lang.reflect.InvocationTargetException
        at java.lang.reflect.Constructor.newInstance0(Native Method)
        at java.lang.reflect.Constructor.newInstance(Constructor.java:343)
        at android.view.LayoutInflater.createView(LayoutInflater.java:647)
        at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:790)
        at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:730)
        at android.view.LayoutInflater.rInflate(LayoutInflater.java:863)
        at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:824)
        at android.view.LayoutInflater.inflate(LayoutInflater.java:515)
        at android.view.LayoutInflater.inflate(LayoutInflater.java:423)
        at android.view.LayoutInflater.inflate(LayoutInflater.java:374)
        at android.support.v7.app.AppCompatDelegateImpl.setContentView(AppCompatDelegateImpl.java:469)
        at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:140)
        at com.example.myapplication.MainAppActivity.onCreate(MainAppActivity.java:98)
        at android.app.Activity.performCreate(Activity.java:7136)
        at android.app.Activity.performCreate(Activity.java:7127)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1271)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2893)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3048)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1808)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:193)
        at android.app.ActivityThread.main(ActivityThread.java:6669)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.view.View.setImportantForAccessibility(int)' on a null object reference
        at android.support.v4.view.ViewCompat.setImportantForAccessibility(ViewCompat.java:1027)
        at android.support.design.internal.BottomNavigationItemView.<init>(BottomNavigationItemView.java:93)
E/AndroidRuntime:     at android.support.design.internal.BottomNavigationItemView.<init>(BottomNavigationItemView.java:77)
        at android.support.design.internal.BottomNavigationItemView.<init>(BottomNavigationItemView.java:73)
        at android.support.design.internal.BottomNavigationMenuView.getNewItem(BottomNavigationMenuView.java:571)
        at android.support.design.internal.BottomNavigationMenuView.buildMenuView(BottomNavigationMenuView.java:507)
        at android.support.design.internal.BottomNavigationPresenter.updateMenuView(BottomNavigationPresenter.java:62)
        at android.support.design.widget.BottomNavigationView.inflateMenu(BottomNavigationView.java:254)
        at android.support.design.widget.BottomNavigationView.<init>(BottomNavigationView.java:187)
        at android.support.design.widget.BottomNavigationView.<init>(BottomNavigationView.java:114)
            ... 28 more

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.myapplication, PID: 23247
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.myapplication/com.example.myapplication.MainAppActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setVisibility(int)' on a null object reference
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2913)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3048)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1808)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:193)
        at android.app.ActivityThread.main(ActivityThread.java:6669)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setVisibility(int)' on a null object reference
        at com.example.myapplication.MainAppActivity$UpdateDBField.onPreExecute(MainAppActivity.java:240)
        at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:648)
        at android.os.AsyncTask.execute(AsyncTask.java:595)
        at com.example.myapplication.MainAppActivity.getLocation(MainAppActivity.java:175)
        at com.example.myapplication.MainAppActivity.onCreate(MainAppActivity.java:148)
        at android.app.Activity.performCreate(Activity.java:7136)
        at android.app.Activity.performCreate(Activity.java:7127)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1271)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2893)

progressBar.setVisibility(View.VISIBLE);
progressLbl.setVisibility(View.VISIBLE);

progressBar = findViewById(R.id.progressBarFragments);
progressLbl = findViewById(R.id.progressLbl);

    implementation 'com.android.support:appcompat-v7:27.1.1'
    implementation 'com.android.support:design:27.1.1'
    implementation 'com.jakewharton:butterknife:8.8.1'
    implementation 'com.android.support:support-v4:27.1.1'