java - 问题 Android Studio 1.0.2 : Fatal Exception: main Process java. lang.NullPointerException

Question

所以，我正在做这个项目，其中包括一个介绍 Activity ，该 Activity 切换到带有抽屉导航的菜单 Activity 。几天前，我在从简介切换到菜单( Android Studio 1.0.2: java.lang.RuntimeException: Unable to start activity ComponentInfo: java.lang.NullPointerException )时遇到了问题，通过更改 name="AppTheme"parent="Theme.AppCompat.Light.DarkActionBar" to name="AppTheme"parent="android:Theme.Holo.Light.DarkActionBar" 感谢 goonerdroid 在我之前的链接中的建议。我现在遇到的问题是，我试图在操作栏右上角的抽屉导航旁边添加一个搜索操作，以便它可以搜索我将添加的不同的 future Activity 和 java。当我运行该程序时，它毫无问题地进入介绍 Activity 。当我单击按钮进入菜单 Activity 时，它显示以下错误:

FATAL EXCEPTION: main
Process: com.wlodsgn.bunbunup, PID: 916
java.lang.NullPointerException
        at com.wlodsgn.bunbunup.MenuActivity.onPrepareOptionsMenu(MenuActivity.java:181)
        at android.app.Activity.onPreparePanel(Activity.java:2556)
        at android.support.v4.app.FragmentActivity.onPrepareOptionsPanel(FragmentActivity.java:469)
        at android.support.v7.app.ActionBarActivity.superOnPrepareOptionsPanel(ActionBarActivity.java:284)
        at android.support.v7.app.ActionBarActivityDelegate.onPrepareOptionsPanel(ActionBarActivityDelegate.java:204)
        at android.support.v7.app.ActionBarActivity.onPrepareOptionsPanel(ActionBarActivity.java:256)
        at android.support.v4.app.FragmentActivity.onPreparePanel(FragmentActivity.java:458)
        at android.support.v7.app.ActionBarActivity.superOnPreparePanel(ActionBarActivity.java:280)
        at android.support.v7.app.ActionBarActivityDelegate$1.onPreparePanel(ActionBarActivityDelegate.java:84)
        at android.support.v7.app.ActionBarActivityDelegateBase.preparePanel(ActionBarActivityDelegateBase.java:1006)
        at android.support.v7.app.ActionBarActivityDelegateBase.doInvalidatePanelMenu(ActionBarActivityDelegateBase.java:1182)
        at android.support.v7.app.ActionBarActivityDelegateBase.access$100(ActionBarActivityDelegateBase.java:79)
        at android.support.v7.app.ActionBarActivityDelegateBase$1.run(ActionBarActivityDelegateBase.java:118)
        at android.os.Handler.handleCallback(Handler.java:733)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:136)
        at android.app.ActivityThread.main(ActivityThread.java:5017)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:515)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
        at dalvik.system.NativeStart.main(Native Method)

这是我更新的 MenuActivity.java:

import java.util.ArrayList;

import android.support.v4.view.MenuItemCompat;
import android.support.v4.view.MenuItemCompat.OnActionExpandListener;
import android.support.v7.app.ActionBar;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.widget.SearchView;
import android.support.v7.widget.SearchView.OnQueryTextListener;
import android.widget.TextView;
import android.widget.Toast;


import android.app.Fragment;
import android.app.FragmentManager;
import android.content.res.Configuration;
import android.content.res.TypedArray;
import android.os.Bundle;
import android.support.v4.app.ActionBarDrawerToggle;
import android.support.v4.widget.DrawerLayout;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListView;

/**
 * Created by WiLo on 2/13/2015.
 */
public class MenuActivity extends ActionBarActivity implements OnQueryTextListener, OnActionExpandListener{

    private TextView texto;

    private DrawerLayout mDrawerLayout;
    private ListView mDrawerList;
    private ActionBarDrawerToggle mDrawerToggle;

    // nav drawer title
    private CharSequence mDrawerTitle;

    // used to store app title
    private CharSequence mTitle;

    // slide menu items
    private String[] navMenuTitles;
    private TypedArray navMenuIcons;

    private ArrayList<NavDrawerItem> navDrawerItems;
    private NavDrawerListAdapter adapter;

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

        texto = (TextView) findViewById(R.id.texto);

        mTitle = mDrawerTitle = getTitle();

        // load slide menu items
        navMenuTitles = getResources().getStringArray(R.array.nav_drawer_items);

        // nav drawer icons from resources
        navMenuIcons = getResources()
                .obtainTypedArray(R.array.nav_drawer_icons);

        mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
        mDrawerList = (ListView) findViewById(R.id.list_slidermenu);

        navDrawerItems = new ArrayList<NavDrawerItem>();

        // agregar un nuevo item al menu deslizante
        // Favoritos
        navDrawerItems.add(new NavDrawerItem(navMenuTitles[0], navMenuIcons.getResourceId(0, -1)));
        // Pedidos
        navDrawerItems.add(new NavDrawerItem(navMenuTitles[1], navMenuIcons.getResourceId(1, -1)));
        // Catologo
        //navDrawerItems.add(new NavDrawerItem(navMenuTitles[2], navMenuIcons.getResourceId(2, -1), true, "Estrenos"));
        // Contacto
        //navDrawerItems.add(new NavDrawerItem(navMenuTitles[3], navMenuIcons.getResourceId(3, -1)));

        // Recycle the typed array
        navMenuIcons.recycle();

        mDrawerList.setOnItemClickListener(new SlideMenuClickListener());

        // setting the nav drawer list adapter
        adapter = new NavDrawerListAdapter(getApplicationContext(),
                navDrawerItems);
        mDrawerList.setAdapter(adapter);

        // enabling action bar app icon and behaving it as toggle button
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        getSupportActionBar().setHomeButtonEnabled(true);

        mDrawerToggle = new ActionBarDrawerToggle(this, mDrawerLayout,
                R.drawable.ic_drawer, //nav menu toggle icon
                R.string.app_name, // nav drawer open - description for accessibility
                R.string.app_name // nav drawer close - description for accessibility
        ) {
            public void onDrawerClosed(View view) {
                getSupportActionBar().setTitle(mTitle);
                // calling onPrepareOptionsMenu() to show action bar icons
                invalidateOptionsMenu();
            }

            public void onDrawerOpened(View drawerView) {
                getSupportActionBar().setTitle(mDrawerTitle);
                // calling onPrepareOptionsMenu() to hide action bar icons
                invalidateOptionsMenu();
            }
        };
        mDrawerLayout.setDrawerListener(mDrawerToggle);

        if (savedInstanceState == null) {
            // on first time display view for first nav item
            displayView(0);
        }
    }

    @Override
    public boolean onMenuItemActionExpand(MenuItem menuItem) {
        Toast.makeText(getApplicationContext(), "Abriendo Busqueda", Toast.LENGTH_SHORT).show();
        return true;
    }

    @Override
    public boolean onMenuItemActionCollapse(MenuItem menuItem) {
        Toast.makeText(getApplicationContext(), "Cerrando Busqueda", Toast.LENGTH_SHORT).show();
        return true;
    }

    @Override
    public boolean onQueryTextSubmit(String s) {
        texto.setText("Buscando...\n\n" + s);
        return false;
    }

    @Override
    public boolean onQueryTextChange(String s) {
        texto.setText("Que buscas? \n\n" + s);
        return false;
    }

    /**
     * Slide menu item click listener
     * */
    private class SlideMenuClickListener implements
            ListView.OnItemClickListener {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position,
                                long id) {
            // display view for selected nav drawer item
            displayView(position);
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu, menu);

        MenuItem searchItem = menu.findItem(R.id.menu3_buscar);

        SearchView searchView = (SearchView) MenuItemCompat.getActionView(searchItem);
        searchView.setOnQueryTextListener(this);

        MenuItemCompat.setOnActionExpandListener(searchItem, this);

        return super.onCreateOptionsMenu(menu);
    }

    /* *
     * Called when invalidateOptionsMenu() is triggered
     */
    @Override
    public boolean onPrepareOptionsMenu(Menu menu) {
        // if nav drawer is opened, hide the action items
        boolean drawerOpen = mDrawerLayout.isDrawerOpen(mDrawerList);
        menu.findItem(R.id.action_settings).setVisible(!drawerOpen);
        return super.onPrepareOptionsMenu(menu);
    }

    /**
     * Diplaying fragment view for selected nav drawer list item
     * */
    private void displayView(int position) {
        // update the main content by replacing fragments
        Fragment fragment = null;
        switch (position) {
            case 0:
                fragment = new FmMenu();
                break;
            case 1:
                fragment = new FmContacto();
                break;

            default:
                break;
        }

        if (fragment != null) {
            FragmentManager fragmentManager = getFragmentManager();
            fragmentManager.beginTransaction()
                    .replace(R.id.frame_container, fragment).commit();

            // update selected item and title, then close the drawer
            mDrawerList.setItemChecked(position, true);
            mDrawerList.setSelection(position);
            setTitle(navMenuTitles[position]);
            mDrawerLayout.closeDrawer(mDrawerList);
        } else {
            // error in creating fragment
            Log.e("BunBunUp", "MenuActivity - Error cuando se creo el fragment");
        }
    }

    @Override
    public void setTitle(CharSequence title) {
        mTitle = title;
        getSupportActionBar().setTitle(mTitle);
    }

    /**
     * When using the ActionBarDrawerToggle, you must call it during
     * onPostCreate() and onConfigurationChanged()...
     */

    @Override
    protected void onPostCreate(Bundle savedInstanceState) {
        super.onPostCreate(savedInstanceState);
        // Sync the toggle state after onRestoreInstanceState has occurred.
        mDrawerToggle.syncState();
    }

    @Override
    public void onConfigurationChanged(Configuration newConfig) {
        super.onConfigurationChanged(newConfig);
        // Pass any configuration change to the drawer toggls
        mDrawerToggle.onConfigurationChanged(newConfig);
    }

}

还有我的 styles.xml:

<resources>

<!-- Base application theme. -->
<style name="AppTheme" parent="Theme.AppCompat">
    <!-- Customize your theme here. -->
</style>


</resources>

更新了 IntroActivity.java

import android.app.Activity;
import android.content.Intent;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.Window;

/**
 * Created by WiLo on 2/13/2015.
 */
public class IntroActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        getWindow().requestFeature(Window.FEATURE_ACTION_BAR);
        /*getActionBar().hide();*/
        setContentView(R.layout.activity_intro);
        Log.i("BunBunUp", "MainActivity Created");
    }

    /**@Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_intro, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }**/

    public void startMenuActivity(View v){
        Intent intent = new Intent(IntroActivity.this, MenuActivity.class);
        startActivity(intent);
    }

    protected void onResume(){
        super.onResume();
        Log.i("BunBunUp", "IntroActivity Resumed");
    }

    protected void onPause(){
        super.onPause();
        Log.i("BunBunUp", "IntroActivity Paused");
    }

    protected void onStop(){
        super.onStop();
        Log.i("BunBunUp", "IntroActivity Stopped");
    }
}

如果您需要调试或任何其他信息，请告诉我。任何帮助将不胜感激。

Answer 1

您正在将 MenuActivity 扩展为 ActionBarActivity，这就是它要求您使用 Theme.AppCompat 的原因。它与您的目标 API 级别无关。请记住 ActionBarActivity 依赖于 Theme.AppCompat 。如果不应用Theme.AppCompat，您就无法使用它。