我也看了这段视频,并阅读了以下问题:
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共享ViewModel以帮助片段和父活动之间的通信
从另一个片段调用fragmentMethod,但不能在ParentFragmentActivity的视图分页器中引用它们
“我的上帝”对这个问题的答复很有帮助,但我仍然不确定在我的情况下做什么是最好的事情,因为我有一个用户可以输入数据的片段,而相同的片段也应该查看数据作为输入的结果。(也许我的第一个错误是这样构建app?)
我提供了一些代码,以防有帮助。
public class AccuracyFragment extends Fragment {
EditText editTextLevel, editTextAccuracy;
private OnFragmentInteractionListener mListener;
public AccuracyFragment() {
// Required empty public constructor
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_accuracy, container, false);
editTextAccuracy = view.findViewById(R.id.text_accuracy_character);
editTextLevel = view.findViewById(R.id.text_level_character);
TextWatcher watcher = new TextWatcher() {
@Override
public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {
//Doing nothing
}
@Override
public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {
//Doing nothing
}
@Override
public void afterTextChanged(Editable editable) {
updateFragment(Float.valueOf(editTextLevel.getText().toString()), Float.valueOf(editTextAccuracy.getText().toString()));
}
};
editTextLevel.addTextChangedListener(watcher);
editTextAccuracy.addTextChangedListener(watcher);
return view;
}
@Override
public void onAttach(Context context) {
super.onAttach(context);
if (context instanceof OnFragmentInteractionListener) {
mListener = (OnFragmentInteractionListener) context;
} else {
throw new RuntimeException(context.toString()
+ " must implement OnFragmentInteractionListener");
}
}
@Override
public void onDetach() {
super.onDetach();
mListener = null; //I don’t know what this does
}
@Override
public void onResume() {
super.onResume();
// updateFragment(); //Should I have this?
}
public interface OnFragmentInteractionListener {
String[] onAccuracyFragmentInputChanged(float levelFromFragment, float accuracyFromFragment); }
public void updateFragment(float level, float accuracy) {
//Complicated method doing things with editTextLevel and editTextAccuracy. However, it doesn’t work when this method is called from outside AccuracyFragment – EditTexts are null
}
@Override
public void onDestroy() {
super.onDestroy();
}
@Override
public void onPause() {
super.onPause();
}
@Override
public void onDestroyView() {
super.onDestroyView();
}
@Override
public void onStop() {
super.onStop();
}
}
public class MainActivity extends AppCompatActivity implements AccuracyFragment.OnFragmentInteractionListener, AdapterView.OnItemSelectedListener {
AccuracyFragment accuracyFragment;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main_new);
selectedID = null;
textView1 = (TextView) findViewById(R.id.text_1);
textView2 = (TextView) findViewById(R.id.text_2);
// Check that the activity is using the layout version with
// the fragment_container FrameLayout
if (findViewById(R.id.fragment_container) != null) {
// However, if we're being restored from a previous state, then we don't need to do anything and should return or else we could end up with overlapping fragments.
if (savedInstanceState != null) {
return;
}
// Create a new Fragment to be placed in the activity layout
accuracyFragment = new AccuracyFragment();
}
}
//This is the core method which takes the value from two EditTexts in the Fragment, and two TextViews in the MainActivity
private String[] getRequiredAccuracy(float firstValueFromActivity, float secondValueFromActivity, float firstValueFromFragment, float secondValueFromFragment) {
//This methods uses parameters from the Activity, and two from the Fragment, and is intended to be called from both the Activity and from the Fragment itself
String returnValues[] = {s, q, r, c}; //This method is too complex to show, but it will end up outputting some values
return returnValues;
}
public void methodCalledUponClick(View view) {
//After showing a Dialog with some choices, I intend to call the method from fragment:
accuracyFragment.updateFragment();
}
@Override
public String[] onAccuracyFragmentInputChanged(float levelFromFragment, float accuracyFromFragment) {
String returnValues[] = {"0", "0", "0"};
if (selectedID != null) {
if (textView1.length() == 0 || textView2.length() == 0) {
//Do nothing if any of these are empty
} else {
returnValues = getRequiredAccuracy(Float.valueOf(textView1.getText().toString()), Float.valueOf(textView2.getText().toString()), levelFromFragment, accuracyFromFragment);
}
}
return returnValues;
}
}
}
您可以继续使用回调/接口来同时与片段和活动通信。
用于创建回调/接口:
public interface CallBackListener {
void onCallBack(String value);// pass any parameter in your onCallBack which you want to return
}
在片段类中:
public class AccuracyFragment extends Fragment {
private CallBackListener callBackListener;
@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
//getActivity() is fully created in onActivityCreated and instanceOf differentiate it between different Activities
if (getActivity() instanceof CallBackListener)
callBackListener = (CallBackListener) getActivity();
}
@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
EditText editText = (EditText) view.findViewById(R.id.edittext);
editText.addTextChangedListener(new TextWatcher() {
@Override
public void afterTextChanged(Editable s) {}
@Override
public void beforeTextChanged(CharSequence s, int start,
int count, int after) {
}
@Override
public void onTextChanged(CharSequence s, int start,
int before, int count) {
if(callBackListener != null)
callBackListener.onCallBack(s.toString());
}
});
}
}
public class MainActivity extends AppCompatActivity implements CallBackListener
{
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
@Override
public void onCallBack(String value) {
Toast.makeText(mContext,"onCallback Called",Toast.LENGTH_LONG).show();
}
}
在我的应用程序中,我使用了一个活动和两个片段。该应用程序使用带有容器的布局,因此片段是通过事务添加的。第一个片段包含列表视图,另一个片段包含列表视图项的详细视图。两个片段都使用setRetainInstance(true)。片段是通过替换事务添加的,并设置了addToBackStack(null)。列表片段包含一个实例变量,其中包含列表的一些信息。现在我正在切换到详细并按回,实例变量为null。我
我已经完成了导航,现在进入第一个片段。在第一个片段中有两个按钮,我需要通过按下这些按钮来切换到一个新的活动。我不明白如何正确地实施它。我犯了一个错误。 代码,eror
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我有个错误 //类别2是片段
先生/女士,我想使用android JAVA将一个片段回调到另一个片段。我试图找到问题,但没有找到解决方案。若我使用接口,它会向活动发送回调响应,这是我不想要的。非常感谢。