继承自 v7.app.AppCompatActivity;的activity去掉标题栏

import android.support.v7.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {

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

    }
}