我在onNavigationItemSelected内部使用了以下调用:

HomeActivity.this.setTitle(item.getTitle());

ActionBar actionBar = getSupportActionBar();
actionBar.setTitle(getString(R.string.titolo));
actionBar.setIcon(R.mipmap.ic_launcher);
actionBar.setDisplayShowHomeEnabled(true);

我在onNavigationItemSelected内部使用了以下调用:

HomeActivity.this.setTitle(item.getTitle());

我得到了非静态方法setTitle(CharSequence)不能从静态上下文错误中引用，因为我在静态PlaceholderFragment类中使用了setTitle()。我通过使用getActivity(). getactionbar()来解决它。setTitle(“新标题”);

为此，可以采用两种方式:XML或Java。看这里:如何更改操作栏上的文本

So:

XML:

<activity android:name=".Hello_World"
              android:label="This is the Hello World Application">
</activity>

Java:

public class TitleBar extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);

       final boolean customTitleSupported = requestWindowFeature(Window.FEATURE_CUSTOM_TITLE);

       setContentView(R.layout.main);


       if ( customTitleSupported ) {
           getWindow().setFeatureInt(Window.FEATURE_CUSTOM_TITLE, R.layout.titlebar);
           }

       final TextView myTitleText = (TextView) findViewById(R.id.myTitle);
       if ( myTitleText != null ) {
           myTitleText.setText("NEW TITLE");

           // user can also set color using "Color" and then "Color value constant"
          // myTitleText.setBackgroundColor(Color.GREEN);
       }
 }
}

您只需要添加这3行代码。将图标替换为您自己的图标。如果你想生成图标，使用这个

getSupportActionBar().setHomeAsUpIndicator(R.drawable.icon_back_arrow);
getActionBar().setHomeButtonEnabled(true);
getActionBar().setDisplayHomeAsUpEnabled(true);