安卓片段崩溃

Question

应用程序甚至无法打开。上次通过实现片段交互侦听器修复。我相信这个错误与我的onAnswerFragmentInteractionListener和我的OnFragmentInteractionListener有关。在它们都被称为相同的东西之前，但我查看了我的类示例，发现其中一个被更改了，所以我去将答案片段中的所有"OnFragmentInteractionListener"更改为"onAnswerFragmentINteractionListener"。

他们的问题也可能是我试图在每个片段之间传递数据。我只是要测试一些方法，看看它们是否有效，但我无法让它毫无防备地工作。

这是代码

主要活动.java

package com.example.nick.assignment4;
import android.net.Uri;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentTransaction;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.TextView;
public abstract class MainActivity extends AppCompatActivity implements AnswerFragment.onAnswerFragmentInteractionListener, FlashcardFragment.OnFragmentInteractionListener {
static String correctOp;
static String selectedOp;
static int correct;
static TextView textCorrect;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

}
@Override
public void onAnswerFragmentInteractionListener(int op) {

}
public static void getCorrectOp(String op){
correctOp = op;
}
}

抽认卡片段：

package com.example.nick.assignment4;
import android.content.Context;
import android.net.Uri;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.TextureView;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import java.util.Random;

/**
* A simple {@link Fragment} subclass.
* Activities that contain this fragment must implement the
* {@link FlashcardFragment.OnFragmentInteractionListener} interface
* to handle interaction events.
*/
public class FlashcardFragment extends Fragment {
private OnFragmentInteractionListener mListener;
Random rand;
int answer;
String[] ops = {"+","-","*"};
public FlashcardFragment() {
// Required empty public constructor
}


@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View flashfrag = inflater.inflate(R.layout.fragment_flashcard, container, false);
// Setting up the flash cards
TextView textNum1 = (TextView) flashfrag.findViewById(R.id.tv_num1);
TextView textNum2 = (TextView) flashfrag.findViewById(R.id.tv_num2);
TextView textAnswer = (TextView) flashfrag.findViewById(R.id.tv_answer);
TextView textOp = (TextView) flashfrag.findViewById(R.id.tv_opp);

// Getting random numbers for Flashcard.
rand = new Random();
int Number1 = rand.nextInt((100 - 1) + 1);
textNum1.setText(""+Number1);
int Number2 = rand.nextInt((Number1 - 1) + 1);
textNum2.setText(""+Number2);
// Getting random operator.
String op = ops[rand.nextInt(3)];
textOp.setText("?");

if(op == "+")
answer = Number1 + Number2;
if(op == "-")
answer = Number1 - Number2;
if(op == "*")
answer = Number1 * Number2;
textAnswer.setText(""+answer);
return flashfrag;
}
// TODO: Rename method, update argument and hook method into UI event
public void onButtonPressed(Uri uri) {
if (mListener != null) {
mListener.onFragmentInteraction(uri);
}
}
@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;
}
public interface OnFragmentInteractionListener {
// TODO: Update argument type and name
void onFragmentInteraction(Uri uri);
}
}

答案片段

package com.example.nick.assignment4;
import android.content.Context;
import android.net.Uri;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;

/**
* A simple {@link Fragment} subclass.
* Activities that contain this fragment must implement the
* {@link AnswerFragment.onAnswerFragmentInteractionListener} interface
* to handle interaction events.
*/
public class AnswerFragment extends Fragment {
private onAnswerFragmentInteractionListener mListener;
public final static int OP_ADD = 0;
public final static int OP_SUB = 1;
public final static int OP_MUL = 2;
public AnswerFragment() {
// Required empty public constructor
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View ansfrag = inflater.inflate(R.layout.fragment_answer, container, false);
// Get buttons
Button addButton = (Button) ansfrag.findViewById(R.id.bt_add);
Button subButton = (Button) ansfrag.findViewById(R.id.bt_sub);
Button mulButton = (Button) ansfrag.findViewById(R.id.bt_mul);
addButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//onButtonPressed(OP_ADD);
//MainActivity.checkAnswer("+");
}
});
subButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//onButtonPressed(OP_SUB);
//MainActivity.checkAnswer("-");
}
});
mulButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//onButtonPressed(OP_MUL);
//MainActivity.checkAnswer("*");
}
});
return ansfrag;
}
// TODO: Rename method, update argument and hook method into UI event
public void onButtonPressed(int op) {
if (mListener != null) {
mListener.onAnswerFragmentInteractionListener(op);
}
}
@Override
public void onAttach(Context context) {
super.onAttach(context);
if (context instanceof onAnswerFragmentInteractionListener) {
mListener = (onAnswerFragmentInteractionListener) context;
} else {
throw new RuntimeException(context.toString()
+ " must implement onAnswerFragmentInteraction");
}
}
@Override
public void onDetach() {
super.onDetach();
mListener = null;
}
public interface onAnswerFragmentInteractionListener {
// TODO: Update argument type and name
void onAnswerFragmentInteractionListener(int op);
}
}

错误代码：

--------- beginning of crash
2018-09-25 19:13:09.405 13585-13585/? E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.nick.assignment4, PID: 13585
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.nick.assignment4/com.example.nick.assignment4.MainActivity}: android.view.InflateException: Binary XML file line #9: Binary XML file line #9: Error inflating class fragment
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2778)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2856)
at android.app.ActivityThread.-wrap11(Unknown Source:0)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1589)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6494)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
Caused by: android.view.InflateException: Binary XML file line #9: Binary XML file line #9: Error inflating class fragment
Caused by: android.view.InflateException: Binary XML file line #9: Error inflating class fragment
Caused by: java.lang.RuntimeException: com.example.nick.assignment4.MainActivity@ff6cb87 must implement OnFragmentInteractionListener
at com.example.nick.assignment4.AnswerFragment.onAttach(AnswerFragment.java:83)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1404)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1684)
at android.support.v4.app.FragmentManagerImpl.addFragment(FragmentManager.java:1930)
at android.support.v4.app.FragmentManagerImpl.onCreateView(FragmentManager.java:3745)
at android.support.v4.app.FragmentController.onCreateView(FragmentController.java:120)
at android.support.v4.app.FragmentActivity.dispatchFragmentsOnCreateView(FragmentActivity.java:405)
at android.support.v4.app.FragmentActivity.onCreateView(FragmentActivity.java:387)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:780)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:730)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:863)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:824)
at android.view.LayoutInflater.inflate(LayoutInflater.java:515)
at android.view.LayoutInflater.inflate(LayoutInflater.java:423)
at android.view.LayoutInflater.inflate(LayoutInflater.java:374)
at android.support.v7.app.AppCompatDelegateImpl.setContentView(AppCompatDelegateImpl.java:469)
at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:140)
at com.example.nick.assignment4.MainActivity.onCreate(MainActivity.java:13)
at android.app.Activity.performCreate(Activity.java:7009)
at android.app.Activity.performCreate(Activity.java:7000)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1214)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2731)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2856)
at android.app.ActivityThread.-wrap11(Unknown Source:0)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1589)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6494)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)

主 XML

<fragment
android:id="@+id/flash_fragment"
android:name="com.example.nick.assignment4.FlashcardFragment"
android:layout_width="369dp"
android:layout_height="276dp"
android:layout_marginStart="8dp"
android:layout_marginLeft="8dp"
android:layout_marginTop="4dp"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<fragment
android:id="@+id/answer_fragment"
android:name="com.example.nick.assignment4.AnswerFragment"
android:layout_width="361dp"
android:layout_height="209dp"
android:layout_marginStart="8dp"
android:layout_marginLeft="8dp"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
android:layout_marginBottom="4dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent" />

Answer 1

Caused by: java.lang.RuntimeException: com.example.nick.assignment4.MainActivity@ff6cb87 must implement OnFragmentInteractionListener

您确定您正在实现 OnFragmentInteractionListener 的所有方法吗？

Answer 2

如果以编程方式插入片段，它将解决错误。 当您从 xml 添加它时，当它添加到 ui 片段的 onAttach 上时，它找不到已实现接口的上下文。这就是为什么它显示错误

Answer 3

在MainActivity中添加此方法：

@Override
public void onFragmentInteraction(Uri uri){
}

Answer 4

在布局 xml 文件中，将android:name替换为如下所示name：

name="com.example.nick.assignment4.FlashcardFragment"

。

name="com.example.nick.assignment4.AnswerFragment"

因为安卓：名称是未知属性。