activity與fragment的交互（一個activity跳轉到另一個fragment）

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        switchFragment(new HeadlinesFragment());
    }
    private void switchFragment(Fragment f) {
        FragmentManager fragmentM = getSupportFragmentManager();//管理對象
        FragmentTransaction trans = fragmentM.beginTransaction();//切換碎片
        trans.replace(R.id.activity_main, f);
        trans.commit();
    }

}