我在面对片段之间以及片段与我的活动之间的交互时遇到了一些困难，特别是在ClickListener方面。
我正在开发由2个片段组成的计算器应用程序：
Buttons（数字和运算符）TextViews（操作和结果）这里的目标是使这两个片段相互通信。我应该将字符和字符串发送到TextView，直到我单击“等于”按钮（在其上放置了ClickListener），但是我似乎既不使用其他按钮也不发送信息（它一直警告我，尽管有接口，但TextView为null）。
这是包含所有按钮和操作符的片段：
package fr.android.calculator.Fragments;
import android.content.Context;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.LinearLayout;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
import fr.android.calculator.R;
/**
* A simple {@link Fragment} subclass.
* Activities that contain this fragment must implement the
* {@link LowerCalculatorFragment.OnFragmentInteractionListener} interface
* to handle interaction events.
* Use the {@link LowerCalculatorFragment#newInstance} factory method to
* create an instance of this fragment.
*/
public class LowerCalculatorFragment extends Fragment {
// TODO: Rename parameter arguments, choose names that match
// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";
// TODO: Rename and change types of parameters
private String mParam1;
private String mParam2;
private OnFragmentInteractionListener mListener;
public LowerCalculatorFragment() {
// Required empty public constructor
}
/**
* Use this factory method to create a new instance of
* this fragment using the provided parameters.
*
* @param param1 Parameter 1.
* @param param2 Parameter 2.
* @return A new instance of fragment LowerCalculatorFragment.
*/
// TODO: Rename and change types and number of parameters
public static LowerCalculatorFragment newInstance(String param1, String param2) {
LowerCalculatorFragment fragment = new LowerCalculatorFragment();
Bundle args = new Bundle();
args.putString(ARG_PARAM1, param1);
args.putString(ARG_PARAM2, param2);
fragment.setArguments(args);
return fragment;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mParam1 = getArguments().getString(ARG_PARAM1);
mParam2 = getArguments().getString(ARG_PARAM2);
}
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view = inflater.inflate(R.layout.fragment_lower_calculator, container, false);
Button button = new Button(getContext());
LinearLayout buttonContainer = view.findViewById(R.id.resultButtonFragment);
button.setText("=");
button.setLayoutParams(new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.MATCH_PARENT));
button.setId(R.id.buttonEqualsFragment);
buttonContainer.addView(button);
button.setOnClickListener(v -> onButtonPressed(v));
return view;
}
public void onViewCreated(View view, @Nullable Bundle savedInstanceState){
super.onViewCreated(view,savedInstanceState);
}
// TODO: Rename method, update argument and hook method into UI event
public void onButtonPressed(View view) {
if (mListener != null) {
mListener.lowerFragmentInteraction(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;
}
/**
* This interface must be implemented by activities that contain this
* fragment to allow an interaction in this fragment to be communicated
* to the activity and potentially other fragments contained in that
* activity.
* <p>
* See the Android Training lesson <a href=
* "http://developer.android.com/training/basics/fragments/communicating.html"
* >Communicating with Other Fragments</a> for more information.
*/
public interface OnFragmentInteractionListener {
// TODO: Update argument type and name
void lowerFragmentInteraction(View view);
}
}
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".Activities.CalculatorSecondActivity"
android:id="@+id/frameLayout">
<LinearLayout
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="match_parent" android:id="@+id/numberOperators" android:baselineAligned="false">
<LinearLayout
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent" android:id="@+id/numbers" android:layout_weight="1">
<LinearLayout
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_weight="1"
android:layout_height="match_parent" android:id="@+id/SevenToPlus">
<Button
android:text="7"
android:layout_width="0dp"
android:layout_height="match_parent" android:id="@+id/button18" android:layout_weight="1"
android:onClick="onButtonClick"/>
<Button
android:text="8"
android:layout_width="0dp"
android:onClick="onButtonClick"
android:layout_height="match_parent" android:id="@+id/button19" android:layout_weight="1"
/>
<Button
android:text="9"
android:layout_width="0dp"
android:onClick="onButtonClick"
android:layout_height="match_parent" android:id="@+id/button20" android:layout_weight="1"
/>
<Button
android:text="+"
android:layout_width="0dp"
android:onClick="onButtonClick"
android:layout_height="match_parent" android:id="@+id/button21" android:layout_weight="1"
/>
</LinearLayout>
<LinearLayout
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_weight="1"
android:layout_height="match_parent" android:id="@+id/FourToMinus">
<Button
android:text="4"
android:layout_width="0dp"
android:onClick="onButtonClick"
android:layout_height="match_parent" android:id="@+id/button22" android:layout_weight="1"
/>
<Button
android:text="5"
android:layout_width="0dp"
android:onClick="onButtonClick"
android:layout_height="match_parent" android:id="@+id/button23" android:layout_weight="1"
/>
<Button
android:text="6"
android:layout_width="0dp"
android:layout_height="match_parent" android:id="@+id/button24" android:layout_weight="1"
/>
<Button
android:text="-"
android:layout_width="0dp"
android:onClick="onButtonClick"
android:layout_height="match_parent" android:id="@+id/button25" android:layout_weight="1"
/>
</LinearLayout>
<LinearLayout
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="match_parent" android:layout_weight="1" android:id="@+id/OneToAsterix">
<Button
android:text="1"
android:layout_width="0dp"
android:onClick="onButtonClick"
android:layout_height="match_parent" android:id="@+id/button26" android:layout_weight="1"
/>
<Button
android:text="2"
android:layout_width="0dp"
android:onClick="onButtonClick"
android:layout_height="match_parent" android:id="@+id/button27" android:layout_weight="1"
/>
<Button
android:text="3"
android:layout_width="0dp"
android:onClick="onButtonClick"
android:layout_height="match_parent" android:id="@+id/button28" android:layout_weight="1"
/>
<Button
android:text="*"
android:layout_width="0dp"
android:onClick="onButtonClick"
android:layout_height="match_parent" android:id="@+id/button29" android:layout_weight="1"
/>
</LinearLayout>
<LinearLayout
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="match_parent" android:layout_weight="1">
<Button
android:text="0"
android:layout_width="0dp"
android:onClick="onButtonClick"
android:layout_height="match_parent" android:id="@+id/button32" android:layout_weight="1"
/>
<Button
android:text="/"
android:layout_width="0dp"
android:onClick="onButtonClick"
android:layout_height="match_parent" android:id="@+id/button33" android:layout_weight="1"
/>
</LinearLayout>
</LinearLayout>
<LinearLayout
android:layout_margin="10dp"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/resultButtonFragment" android:layout_weight="4" android:orientation="vertical"
>
</LinearLayout>
</LinearLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
这是包含两个TextViews的片段：
package fr.android.calculator.Fragments;
import android.content.Context;
import android.os.Bundle;
import android.widget.TextView;
import androidx.fragment.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import fr.android.calculator.R;
/**
* A simple {@link Fragment} subclass.
* Activities that contain this fragment must implement the
* {@link UpperCalculatorFragment.OnFragmentInteractionListener} interface
* to handle interaction events.
* Use the {@link UpperCalculatorFragment#newInstance} factory method to
* create an instance of this fragment.
*/
public class UpperCalculatorFragment extends Fragment {
// TODO: Rename parameter arguments, choose names that match
// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";
// TODO: Rename and change types of parameters
private String mParam1;
private String mParam2;
private TextView resultDisplay;
private TextView operations;
private OnFragmentInteractionListener mListener;
public UpperCalculatorFragment() {
// Required empty public constructor
}
/**
* Use this factory method to create a new instance of
* this fragment using the provided parameters.
*
* @param param1 Parameter 1.
* @param param2 Parameter 2.
* @return A new instance of fragment UpperCalculatorFragment.
*/
// TODO: Rename and change types and number of parameters
public static UpperCalculatorFragment newInstance(String param1, String param2) {
UpperCalculatorFragment fragment = new UpperCalculatorFragment();
Bundle args = new Bundle();
args.putString(ARG_PARAM1, param1);
args.putString(ARG_PARAM2, param2);
fragment.setArguments(args);
return fragment;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mParam1 = getArguments().getString(ARG_PARAM1);
mParam2 = getArguments().getString(ARG_PARAM2);
}
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view = inflater.inflate(R.layout.fragment_upper_calculator, container, false);
operations = view.findViewById(R.id.operationsFragment);
resultDisplay = view.findViewById(R.id.resultDisplayFragment);
return view;
}
public void setOperationsText(String operationsText){
operations.setText(operationsText);
}
public void setResultDisplayText(String resultDisplayText){
resultDisplay.setText(resultDisplayText);
}
// TODO: Rename method, update argument and hook method into UI event
public void onButtonPressed(String operations) {
if (mListener != null) {
mListener.operationsFragmentInteraction(operations);
}
}
@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;
}
/**
* This interface must be implemented by activities that contain this
* fragment to allow an interaction in this fragment to be communicated
* to the activity and potentially other fragments contained in that
* activity.
* <p>
* See the Android Training lesson <a href=
* "http://developer.android.com/training/basics/fragments/communicating.html"
* >Communicating with Other Fragments</a> for more information.
*/
public interface OnFragmentInteractionListener {
// TODO: Update argument type and name
void operationsFragmentInteraction(String operations);
void resultDisplayFragmentInteraction(String resultDisplay);
}
}
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".Fragments.UpperCalculatorFragment"
>
<LinearLayout
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:background="@drawable/textview_border"
android:layout_marginRight="20dp"
android:layout_width="match_parent"
android:layout_height="match_parent" android:id="@+id/operationsFragment" android:layout_weight="2"/>
<TextView
android:background="@drawable/textview_border"
android:layout_width="match_parent"
android:layout_height="match_parent" android:id="@+id/resultDisplayFragment" android:layout_weight="3"/>
</LinearLayout>
</FrameLayout>
中间的活动本身就是这个：
package fr.android.calculator.Activities;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Handler;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;
import fr.android.calculator.Fragments.LowerCalculatorFragment;
import fr.android.calculator.Fragments.UpperCalculatorFragment;
import fr.android.calculator.R;
import org.mozilla.javascript.Context;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.Socket;
public class CalculatorSecondActivity extends AppCompatActivity implements LowerCalculatorFragment.OnFragmentInteractionListener, UpperCalculatorFragment.OnFragmentInteractionListener {
private LowerCalculatorFragment lowerCalculatorFragment;
private UpperCalculatorFragment upperCalculatorFragment;
private Context rhino = Context.enter(); // runtime environment
private TextView operations;
private Button value;
private String result;
private TextView resultDisplay;
private Handler handler;
private DataInputStream dataInputStream;
private DataOutputStream dataOutputStream;
private String resp;
private Socket socket;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_calculator_second);
lowerCalculatorFragment = LowerCalculatorFragment.newInstance("fragment", "you");
upperCalculatorFragment = UpperCalculatorFragment.newInstance("new fragment", "you 2");
getSupportFragmentManager().beginTransaction().add(R.id.lowerCalculator, lowerCalculatorFragment);
getSupportFragmentManager().beginTransaction().add(R.id.upperCalculator, upperCalculatorFragment);
getSupportFragmentManager().beginTransaction().commit();
}
@Override
public void operationsFragmentInteraction(String message) {
upperCalculatorFragment = (UpperCalculatorFragment) getSupportFragmentManager().findFragmentById(R.id.upperCalculator);
upperCalculatorFragment.setOperationsText(message);
}
@Override
public void resultDisplayFragmentInteraction(String message) {
upperCalculatorFragment = (UpperCalculatorFragment) getSupportFragmentManager().findFragmentById(R.id.upperCalculator);
upperCalculatorFragment.setResultDisplayText(message);
}
@Override
public void lowerFragmentInteraction(View view) {
value = view.findViewById(view.getId());
System.out.println("Value : " + value.getText());
if (value != view.findViewById(R.id.buttonEqualsFragment)) {
System.out.println("Value : " + value.getText());
operationsFragmentInteraction((String) value.getText());
} else {
// Avec Async
new AsyncTaskRunner().execute((String) operations.getText());
/* Avec Handler*/
//calculate((String) operations.getText());
}
}
public void onButtonClick(View view){
lowerCalculatorFragment.onButtonPressed(view);
}
public void calculate(String operations) {
Runnable runnable = () -> {
try {
socket = new Socket("10.0.2.2", 9876);
dataInputStream = new DataInputStream(socket.getInputStream());
dataOutputStream = new DataOutputStream(socket.getOutputStream());
dataOutputStream.writeUTF(operations);
result = dataInputStream.readUTF();
dataOutputStream.close();
dataInputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
handler.post(() -> resultDisplay.setText(result));
};
new Thread(runnable).start();
}
private class AsyncTaskRunner extends AsyncTask<String, String, String> {
@Override
protected String doInBackground(String... params) {
try {
socket = new Socket("10.0.2.2", 9876);
dataInputStream = new DataInputStream(socket.getInputStream());
dataOutputStream = new DataOutputStream(socket.getOutputStream());
dataOutputStream.writeUTF(params[0]);
result = dataInputStream.readUTF();
dataOutputStream.close();
dataInputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
publishProgress(params[0]); // Calls onProgressUpdate()
resp = "Slept for " + 5 + " seconds";
return resp;
}
protected void onProgressUpdate(String... text) {
resultDisplayFragmentInteraction(result);
}
}
}
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
tools:showIn="@layout/activity_calculator_second"
tools:context=".Activities.CalculatorSecondActivity">
<LinearLayout android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent" android:weightSum="5">
<fragment android:layout_width="match_parent" android:layout_height="119dp"
android:name="fr.android.calculator.Fragments.UpperCalculatorFragment"
android:id="@+id/upperCalculator"
tools:layout="@layout/fragment_upper_calculator"
android:layout_weight="1"/>
<fragment android:name="fr.android.calculator.Fragments.LowerCalculatorFragment"
android:layout_width="409dp" android:layout_height="413dp"
android:id="@+id/lowerCalculator" tools:layout="@layout/fragment_lower_calculator"
android:layout_weight="4"/>
</LinearLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
你们有什么想法吗？
谢谢，
票价。
问题是您试图在活动中而不是在片段中显示信息。尝试以下建议。
在您的UpperCalculatorFragment类中，将其放在顶部：
private Textview operations, results;
然后在onCreateView()中添加以下内容，以确保文本视图不为空：
operations = view.findViewById(R.id.operationsFragment);
results = view.findViewById(R.id.resultDisplayFragment);
接下来，您必须在此片段（UpperCalculatorFragment）中定义一个公共方法，该方法将处理来自Activity的信息。我只显示结果，您也需要另一个操作]
public void displayResult(String result){
results.setText(result);//this displays the result on textview
}
要显示结果/操作，您必须像这样从CalculatorSecondActivity调用该方法；
public void displayResultInFragment(String message) {
UpperCalculatorFragment upperFrag =
(UpperCalculatorFragment) getSupportFragmentManager()
.findFragmentById(R.id.upperCalculator);
//show the result here after all calculation
upperFrag.displayResult(message);
}