public class MainActivity extends Activity {    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);                //[1]获取Fragment的管理者        FragmentManager fragmentManager = getFragmentManager();        //[2]开启事物         FragmentTransaction transaction = fragmentManager.beginTransaction();        //[3]动态替换        transaction.replace(R.id.ll1, new Fragment1(),"f1");        transaction.replace(R.id.ll2, new Fragment2(),"f2");                //[4]最后一步 记得commit        transaction.commit();                    }}

public class Fragment1 extends Fragment {    @Override    public View onCreateView(LayoutInflater inflater, ViewGroup container,            Bundle savedInstanceState) {        View view = inflater.inflate(R.layout.fragment1, null);        //[1]找到按钮设置点击事件         view.findViewById(R.id.button1).setOnClickListener(new OnClickListener() {                        @Override            public void onClick(View v) {                Toast.makeText(getActivity(), "jagjajgl", 1).show();                //[2]修改Fragment2里面textview的值                 Fragment2 f2 = (Fragment2) getActivity().getFragmentManager().findFragmentByTag("f2");                f2.setText("haahha");                            }        });                return view;    }}

public class Fragment2 extends Fragment {    private TextView tView;    @Override    public View onCreateView(LayoutInflater inflater, ViewGroup container,            Bundle savedInstanceState) {        View view = inflater.inflate(R.layout.fragment2, null);                tView = (TextView) view.findViewById(R.id.tv);                return view;    }            //修改textview值的方法    public void setText(String content){        tView.setText(content);    }}