试图从片段中调用我的活动中的方法。我想要片段给方法数据,并在方法返回时获得数据。我想实现类似于对静态方法的调用,但不使用静态,因为它会在活动中产生问题。
新的片段,所以我需要一个简单的和教学的解释!
谢谢!
试图从片段中调用我的活动中的方法。我想要片段给方法数据,并在方法返回时获得数据。我想实现类似于对静态方法的调用,但不使用静态,因为它会在活动中产生问题。
新的片段,所以我需要一个简单的和教学的解释!
谢谢!
当前回答
对于Kotlin,请尝试一下
class DataForm : Fragment() {
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
Tasks(this).getData()
}
fun getResponse(response: String) {
// code
}
}
class Tasks(private val context: Any) {
fun getData() {
val getContext = (context as DataForm).activity
val getFragment = (context as DataForm)
val responseListener = Response.Listener<String> { response ->
getFragment.getResponse(response)
}
val errorListener = Response.ErrorListener { error ->
error.printStackTrace();
}
val stringRequest = StringRequest(Request.Method.GET, url, responseListener, errorListener)
Volley.newRequestQueue(getContext).add(stringRequest)
}
}
其他回答
以下是我的做法:
首先制作接口
interface NavigationInterface {
fun closeActivity()
}
接下来确保activity实现了接口并覆盖了接口方法
class NotesActivity : AppCompatActivity(), NavigationInterface {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_notes)
setSupportActionBar(findViewById(R.id.toolbar))
}
override fun closeActivity() {
this.finish()
}
}
然后确保在片段中创建接口侦听器
private lateinit var navigationInterface: NavigationInterface
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
//establish interface communication
activity?.let {
instantiateNavigationInterface(it)
}
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_notes_info, container, false)
}
private fun instantiateNavigationInterface(context: FragmentActivity) {
navigationInterface = context as NavigationInterface
}
然后你就可以这样打电话了:
view.findViewById<Button>(R.id.button_second).setOnClickListener {
navigationInterface.closeActivity()
}
对于Kotlin,请尝试一下
class DataForm : Fragment() {
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
Tasks(this).getData()
}
fun getResponse(response: String) {
// code
}
}
class Tasks(private val context: Any) {
fun getData() {
val getContext = (context as DataForm).activity
val getFragment = (context as DataForm)
val responseListener = Response.Listener<String> { response ->
getFragment.getResponse(response)
}
val errorListener = Response.ErrorListener { error ->
error.printStackTrace();
}
val stringRequest = StringRequest(Request.Method.GET, url, responseListener, errorListener)
Volley.newRequestQueue(getContext).add(stringRequest)
}
}
谢谢@BIJAY_JHA和@Manaus。我使用Kotlin版本来调用我的signIn()方法,该方法存在于活动中,并且我从一个片段中调用。我在Android中使用导航架构,所以监听器接口模式不在片段中:
(activity as MainActivity).signIn()
对于通过fragment访问Activity中声明的函数,请使用接口,如marco的回答所示。
如果你没有标签或id,你可以通过活动访问Fragment中声明的函数
private void setupViewPager(ViewPager viewPager) {
//fragmentOne,fragmentTwo and fragmentThree are all global variables
fragmentOne= new FragmentOne();
fragmentTwo= new FragmentTwo();
fragmentThree = new FragmentThree();
viewPagerAdapteradapter = new ViewPagerAdapter(getSupportFragmentManager());
viewPagerAdapteradapter.addFragment(fragmentOne, "Frag1");
viewPagerAdapteradapter.addFragment(fragmentTwo, "Frag2");
viewPagerAdapteradapter.addFragment(fragmentThree, "Frag3");
//viewPager has to be instantiated when you create the activity:
//ViewPager viewPager = (ViewPager)findViewById(R.id.pager);
//setupViewPager(viewPager);
//Where R.id.pager is the id of the viewPager defined in your activity's xml page.
viewPager.setAdapter(viewPagerAdapteradapter);
//frag1 and frag2 are also global variables
frag1 = (FragmentOne)viewPagerAdapteradapter.mFragmentList.get(0);
frag2 = (FragmentTwo)viewPagerAdapteradapter.mFragmentList.get(1);;
//You can use the variable fragmentOne or frag1 to access functions declared in FragmentOne
}
这是ViewpagerAdapterClass
class ViewPagerAdapter extends FragmentPagerAdapter {
public final List<Fragment> mFragmentList = new ArrayList<>();
private final List<String> mFragmentTitleList = new ArrayList<>();
public ViewPagerAdapter(FragmentManager manager) {
super(manager);
}
@Override
public Fragment getItem(int position) {
return mFragmentList.get(position);
}
@Override
public int getCount() {
return mFragmentList.size();
}
public void addFragment(Fragment fragment, String title) {
mFragmentList.add(fragment);
mFragmentTitleList.add(title);
}
@Override
public CharSequence getPageTitle(int position) {
return mFragmentTitleList.get(position);
}
}
这个答案是给像我这样的新手的。祝你有愉快的一天。
我认为在片段初始化时传递活动实例是一个更好的方法。我像下面这样传递实例:
class FragmentSignUp : Fragment() {
private lateinit var authActivity: AuthenticateActivity
...
companion object {
fun newInstance(a: AuthenticateActivity): FragmentSignUp {
val fragment = FragmentSignUp()
fragment.authActivity = a
return fragment
}
}
}
现在,您可以使用传递的活动实例初始化片段,也可以调用活动中的任何公共方法。像下图:
val fragmentManager = supportFragmentManager
val fragment = FragmentSignUp.newInstance(this)
fragmentManager.beginTransaction().replace(R.id.authenticate_fragment, fragment, FragmentSignUp::class.java.simpleName)
.commit()
你现在可以在你的片段中访问你的activity公共方法;就像我的例子:
authactivity.goToLogInFragment()
在Java中,你的片段类应该是:
public class FragmentSignUp extends Fragment {
private AuthenticateActivity authActivity;
public static FragmentSignUp newInstance(AuthenticateActivity a) {
FragmentSignUp fragment = new FragmentSignUp();
fragment.authActivity = a;
return fragment;
}
}
注意:我们也可以将活动直接注入到片段构造函数中。但在大多数情况下,我们应该避免这样做,因为它会导致一些运行时问题。