如何在Material Design中添加ActionBar？

Question

我要在应用程序中查看操作栏吗？

我可以在第一页中查看工具栏，但不能在第二页中显示。

我遇到了一些错误...

这是我的java代码

public class ContentPage extends ActionBarActivity implements FragmentDrawer.FragmentDrawerListener {

private static String TAG = MainActivity.class.getSimpleName();

private Toolbar mToolbar;
private FragmentDrawer drawerFragment;

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

    mToolbar = (Toolbar) findViewById(R.id.toolbar);

   setSupportActionBar(mToolbar);
   getSupportActionBar().setDisplayShowHomeEnabled(true);

    drawerFragment = (FragmentDrawer)
            getSupportFragmentManager().findFragmentById(R.id.fragment_navigation_drawer);
    drawerFragment.setUp(R.id.fragment_navigation_drawer, (DrawerLayout) findViewById(R.id.drawer_layout), mToolbar);
    drawerFragment.setDrawerListener(this);

    // display the first navigation drawer view on app launch
    displayView(0);
}


@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_main, 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);
}

@Override
public void onDrawerItemSelected(View view, int position) {
    displayView(position);
}

private void displayView(int position) {
    Fragment fragment = null;
    String title = getString(R.string.app_name);
    switch (position) {
        case 0:
            fragment = new HomeFragment();
            title = getString(R.string.title_home);
            break;
        default:
            break;
    }

    if (fragment != null) {
        FragmentManager fragmentManager = getSupportFragmentManager();
        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
        fragmentTransaction.replace(R.id.container_body, fragment);
        fragmentTransaction.commit();

        // set the toolbar title
        getSupportActionBar().setTitle(title);
    }
}

}

这是我看到的错误...

12-22 16:34:22.022 12457-12457/nextappsbd.testapplicationforhamza E/AndroidRuntime: FATAL EXCEPTION: main
                                                                                Process: nextappsbd.testapplicationforhamza, PID: 12457
                                                                                java.lang.RuntimeException: Unable to start activity ComponentInfo{nextappsbd.testapplicationforhamza/nextappsbd.testapplicationforhamza.ContentPage}: java.lang.NullPointerException
                                                                                    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2377)
                                                                                    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2440)
                                                                                    at android.app.ActivityThread.access$800(ActivityThread.java:151)
                                                                                    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1342)
                                                                                    at android.os.Handler.dispatchMessage(Handler.java:110)
                                                                                    at android.os.Looper.loop(Looper.java:193)
                                                                                    at android.app.ActivityThread.main(ActivityThread.java:5344)
                                                                                    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:860)
                                                                                    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:676)
                                                                                    at dalvik.system.NativeStart.main(Native Method)
                                                                                 Caused by: java.lang.NullPointerException
                                                                                    at android.support.v7.widget.ToolbarWidgetWrapper.<init>(ToolbarWidgetWrapper.java:98)
                                                                                    at android.support.v7.widget.ToolbarWidgetWrapper.<init>(ToolbarWidgetWrapper.java:91)
                                                                                    at android.support.v7.app.ToolbarActionBar.<init>(ToolbarActionBar.java:73)
                                                                                    at android.support.v7.app.AppCompatDelegateImplV7.setSupportActionBar(AppCompatDelegateImplV7.java:205)
                                                                                    at android.support.v7.app.AppCompatActivity.setSupportActionBar(AppCompatActivity.java:99)
                                                                                    at nextappsbd.testapplicationforhamza.ContentPage.onCreate(ContentPage.java:28)
                                                                                    at android.app.Activity.performCreate(Activity.java:5361)
                                                                                    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1088)
                                                                                    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2331)
                                                                                    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2440) 
                                                                                    at android.app.ActivityThread.access$800(ActivityThread.java:151) 
                                                                                    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1342) 
                                                                                    at android.os.Handler.dispatchMessage(Handler.java:110) 
                                                                                    at android.os.Looper.loop(Looper.java:193) 
                                                                                    at android.app.ActivityThread.main(ActivityThread.java:5344) 
                                                                                    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:860) 
                                                                                    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:676) 
                                                                                    at dalvik.system.NativeStart.main(Native Method) 

这是我的MainActivity ..

public class MainActivity extends ActionBarActivity implements FragmentDrawer.FragmentDrawerListener {

private static String TAG = MainActivity.class.getSimpleName();

private Toolbar mToolbar;
private FragmentDrawer drawerFragment;

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

    mToolbar = (Toolbar) findViewById(R.id.toolbar);

    setSupportActionBar(mToolbar);
    getSupportActionBar().setDisplayShowHomeEnabled(true);

    drawerFragment = (FragmentDrawer)
            getSupportFragmentManager().findFragmentById(R.id.fragment_navigation_drawer);
    drawerFragment.setUp(R.id.fragment_navigation_drawer, (DrawerLayout) findViewById(R.id.drawer_layout), mToolbar);
    drawerFragment.setDrawerListener(this);

    // display the first navigation drawer view on app launch
    displayView(0);
}


@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_main, 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);
}

@Override
public void onDrawerItemSelected(View view, int position) {
    displayView(position);
}

private void displayView(int position) {
    Fragment fragment = null;
    String title = getString(R.string.app_name);
    switch (position) {
        case 0:
            fragment = new HomeFragment();
            title = getString(R.string.title_home);
            break;
        default:
            break;
    }

    if (fragment != null) {
        FragmentManager fragmentManager = getSupportFragmentManager();
        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
        fragmentTransaction.replace(R.id.container_body, fragment);
        fragmentTransaction.commit();

        // set the toolbar title
        getSupportActionBar().setTitle(title);
    }
}

}

我在MainActivity中显示工具栏，但在ContentPage Activity中无法显示此工具栏。

我该如何解决？

Answer 1

从22.1.0版本开始 ，不推荐使用ActionBarActivity类。 您应该使用AppCompatActivity 。

public class ContentPage extends AppCompatActivity

然后

    @Override
    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_content_page);
    mToolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(mToolbar);

Answer 2

查看Android开发者网站

您也可以通过这个例子