MainActivity

package com.code.source.toolbartitelcenter;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.Toolbar;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        TextView toolbarText = (TextView)
                findViewById(R.id.toolbar_text);
        if (toolbarText != null && toolbar != null) {
            toolbarText.setText("source code indonesia"); //bisa di ubah
          //  toolbarText.setText(getTitle());    // tidak bisa di ubah
            setSupportActionBar(toolbar);
        }
    }
}