在BottomNavigationView中添加4个菜单（项目）时显示错误

Question

我是 android 新手 .. 试图构建在片段内具有 webview 的应用程序，并且在底部它在单击特定项目片段时具有 BottomNavigationView 根据 click 更改。

当我添加 4 个应用程序开始崩溃时，BottomNavigationView 中有 3 个项目时，一切正常。

错误是休耕 -

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: in.xparticle.digitalkabadi, PID: 23369
    java.lang.RuntimeException: Unable to start activity ComponentInfo{in.xparticle.digitalkabadi/in.xparticle.digitalkabadi.MainActivity}: android.view.InflateException: Binary XML file line #19 in in.xparticle.digitalkabadi:layout/activity_main: Binary XML file line #19 in in.xparticle.digitalkabadi:layout/activity_main: Error inflating class com.google.android.material.bottomnavigation.BottomNavigationView
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3270)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3409)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2016)
        at android.os.Handler.dispatchMessage(Handler.java:107)
        at android.os.Looper.loop(Looper.java:214)
        at android.app.ActivityThread.main(ActivityThread.java:7356)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:491)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:940)
     Caused by: android.view.InflateException: Binary XML file line #19 in in.xparticle.digitalkabadi:layout/activity_main: Binary XML file line #19 in in.xparticle.digitalkabadi:layout/activity_main: Error inflating class com.google.android.material.bottomnavigation.BottomNavigationView
     Caused by: android.view.InflateException: Binary XML file line #19 in in.xparticle.digitalkabadi:layout/activity_main: Error inflating class com.google.android.material.bottomnavigation.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:854)
        at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:1006)
        at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:961)
        at android.view.LayoutInflater.rInflate(LayoutInflater.java:1123)
        at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:1084)
        at android.view.LayoutInflater.inflate(LayoutInflater.java:682)
        at android.view.LayoutInflater.inflate(LayoutInflater.java:534)
        at android.view.LayoutInflater.inflate(LayoutInflater.java:481)
        at androidx.appcompat.app.AppCompatDelegateImpl.setContentView(AppCompatDelegateImpl.java:696)
        at androidx.appcompat.app.AppCompatActivity.setContentView(AppCompatActivity.java:170)
        at in.xparticle.digitalkabadi.MainActivity.onCreate(MainActivity.java:17)
        at android.app.Activity.performCreate(Activity.java:7824)
        at android.app.Activity.performCreate(Activity.java:7813)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1306)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3245)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3409)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2016)
        at android.os.Handler.dispatchMessage(Handler.java:107)
        at android.os.Looper.loop(Looper.java:214)
        at android.app.ActivityThread.main(ActivityThread.java:7356)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:491)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:940)
E/AndroidRuntime: Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.view.View.setImportantForAccessibility(int)' on a null object reference
        at androidx.core.view.ViewCompat.setImportantForAccessibility(ViewCompat.java:1119)
        at com.google.android.material.bottomnavigation.BottomNavigationItemView.<init>(BottomNavigationItemView.java:104)
        at com.google.android.material.bottomnavigation.BottomNavigationItemView.<init>(BottomNavigationItemView.java:87)
        at com.google.android.material.bottomnavigation.BottomNavigationItemView.<init>(BottomNavigationItemView.java:83)
        at com.google.android.material.bottomnavigation.BottomNavigationMenuView.getNewItem(BottomNavigationMenuView.java:606)
        at com.google.android.material.bottomnavigation.BottomNavigationMenuView.buildMenuView(BottomNavigationMenuView.java:538)
        at com.google.android.material.bottomnavigation.BottomNavigationPresenter.updateMenuView(BottomNavigationPresenter.java:67)
        at com.google.android.material.bottomnavigation.BottomNavigationView.inflateMenu(BottomNavigationView.java:344)
        at com.google.android.material.bottomnavigation.BottomNavigationView.<init>(BottomNavigationView.java:226)
        at com.google.android.material.bottomnavigation.BottomNavigationView.<init>(BottomNavigationView.java:133)
            ... 28 more

主活动.java

public class MainActivity extends AppCompatActivity {

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

        BottomNavigationView bottomNav = findViewById(R.id.bottom_navigation);
        bottomNav.setOnNavigationItemSelectedListener(navListener);

        getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,
                new HomeFragment()).commit();
    }

    private BottomNavigationView.OnNavigationItemSelectedListener navListener =
            new BottomNavigationView.OnNavigationItemSelectedListener() {
                @Override
                public boolean onNavigationItemSelected(@NonNull MenuItem item) {
                    Fragment selectedFragment = null;

                    switch (item.getItemId()){
                        case R.id.nav_home:
                            selectedFragment = new HomeFragment();
                            break;
                        case R.id.nav_scrape_price:
                            selectedFragment = new ScrapePriceFragment();
                            break;
                        case R.id.nav_aboutUs:
                            selectedFragment = new AboutUsFragment();
                            break;
                        case R.id.nav_scrape_Process:
                            selectedFragment = new AboutUsFragment();
                            break;

                    }
                    assert selectedFragment != null;
                    getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,
                            selectedFragment).commit();
                    return true;
                }

            };
}

Answer 1

试试这个 -->

public class MainActivity extends AppCompatActivity implements BottomNavigationView.OnNavigationItemSelectedListener {


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

    //loading the default fragment
    loadFragment(new FirstFragment());

    //getting bottom navigation view and attaching the listener
    BottomNavigationView navigation = findViewById(R.id.bottom_navigation);
    navigation.setOnNavigationItemSelectedListener(this);
}


@Override
public boolean onNavigationItemSelected(@NonNull MenuItem item) {
    Fragment fragment = null;

    switch (item.getItemId()) {
        case R.id.id1:
            fragment = new FirstFragment();
            break;

        case R.id.id2:
            fragment = new SecondFragment();
            break;

        case R.id.id3:
            fragment = new thirsFragment();
            break;

        case R.id.id4:
            fragment = new fourthFragment();
            break;
    }

    return loadFragment(fragment);
}

private boolean loadFragment(Fragment fragment) {
    //switching fragment
    if (fragment != null) {
        getSupportFragmentManager()
                .beginTransaction()
                .replace(R.id.fragment_container, fragment)
                .commit();
        return true;
    }
    return false;
}

}