Iam在Dialog片段中收到运行时错误。在程序的运行时工作顺利，但当谈到对话框外观时，程序崩溃了...........有人告诉我错误在哪里我无法解决我的问题。
import android.content.Intent;
import android.content.SharedPreferences;
import android.graphics.Typeface;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Toast;
import java.util.Set;
public class MainActivity extends AppCompatActivity {
public static final String GUESSES = "settings_numberOfGuesses";
public static final String ANIMALS_TYPE = "settings_animalType";
public static final String QUIZ_BACKGROUND_COLOR = "settings_quiz_background_color";
public static final String QUIZ_FONT = "settings_quiz_font";
private boolean isSettingsChanged = false;
static Typeface azkiaDemo;
static Typeface chunkFive;
static Typeface fontleroyBrown;
static Typeface hauntedEyes;
static Typeface knightBrushDemo;
static Typeface wonderbarDemo;
MainActivityFragment myAnimalQuizFragment;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
azkiaDemo = Typeface.createFromAsset(getAssets(),"fonts/Azkia demo.otf");
chunkFive = Typeface.createFromAsset(getAssets(),"fonts/Chunkfive.otf");
fontleroyBrown = Typeface.createFromAsset(getAssets(),"fonts/FontleroyBrown.ttf");
hauntedEyes = Typeface.createFromAsset(getAssets(),"fonts/Haunted Eyes.otf");
knightBrushDemo = Typeface.createFromAsset(getAssets(),"fonts/Knight Brush Demo.otf");
wonderbarDemo = Typeface.createFromAsset(getAssets(),"fonts/Wonderbar Demo.otf");
PreferenceManager.setDefaultValues(this, R.xml.quiz_preferences, false);
PreferenceManager.getDefaultSharedPreferences(this).
registerOnSharedPreferenceChangeListener(settingsChangedListener);
myAnimalQuizFragment = (MainActivityFragment) getSupportFragmentManager().findFragmentById(R.id.animalQuizFragment);
myAnimalQuizFragment.modifyAnimalGuessRows(PreferenceManager.getDefaultSharedPreferences(this));
myAnimalQuizFragment.modifyTypeofAnimals(PreferenceManager.getDefaultSharedPreferences(this));
myAnimalQuizFragment.modifyQuizFont(PreferenceManager.getDefaultSharedPreferences(this));
myAnimalQuizFragment.modifyBackgroundColor(PreferenceManager.getDefaultSharedPreferences(this));
myAnimalQuizFragment.resetAnimalQuiz();
isSettingsChanged = false;
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
Intent preferencesIntent = new Intent(this,SettingsActivity.class);
startActivity(preferencesIntent);
return super.onOptionsItemSelected(item);
}
private SharedPreferences.OnSharedPreferenceChangeListener settingsChangedListener =
new SharedPreferences.OnSharedPreferenceChangeListener() {
@Override
public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
isSettingsChanged = true;
if (key.equals(GUESSES)){
myAnimalQuizFragment.modifyAnimalGuessRows(sharedPreferences);
myAnimalQuizFragment.resetAnimalQuiz();
}else if (key.equals(ANIMALS_TYPE)){
Set<String> animalTypes = sharedPreferences.getStringSet(ANIMALS_TYPE,null);
if (animalTypes != null && animalTypes.size() > 0){
myAnimalQuizFragment.modifyTypeofAnimals(sharedPreferences);
myAnimalQuizFragment.resetAnimalQuiz();
}else {
SharedPreferences.Editor editor = sharedPreferences.edit();
animalTypes.add(getString(R.string.default_animal_type));
editor.putStringSet(ANIMALS_TYPE, animalTypes); // here we provided default value also.......
editor.apply();
Toast.makeText(MainActivity.this, R.string.default_animalType_message, Toast.LENGTH_SHORT).show();
}
}else if (key.equals(QUIZ_FONT)){
myAnimalQuizFragment.modifyQuizFont(sharedPreferences);
myAnimalQuizFragment.resetAnimalQuiz();
}else if (key.equals(QUIZ_BACKGROUND_COLOR)){
myAnimalQuizFragment.modifyBackgroundColor(sharedPreferences);
myAnimalQuizFragment.resetAnimalQuiz();
}
Toast.makeText(MainActivity.this, R.string.toast_message , Toast.LENGTH_SHORT).show();
}
};
public void showDialog(){
ExampleDialog exampleDialog = new ExampleDialog();
exampleDialog.setCancelable(false);
exampleDialog.show(getFragmentManager(),"Animal_Quiz_Result");
}
}
import android.animation.Animator;
import android.content.SharedPreferences;
import android.content.res.AssetManager;
import android.graphics.Color;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.os.Handler;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewAnimationUtils;
import android.view.ViewGroup;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.TextView;
import java.io.IOException;
import java.io.InputStream;
import java.security.SecureRandom;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Set;
public class MainActivityFragment extends Fragment {
public static final int NUMBER_OF_ANIMALS_INCLUDED_IN_QUIZ = 10;
private List<String> allAnimalsNameList;
private List<String> animalNamesQuizList;
private Set<String> animalTypesInQuiz;
private String correctAnimalsAnswer;
public static int numberOfAllGuesses;
private int numberOfAnimalGuessRows;
private int numberOfRightAnswers;
private SecureRandom secureRandomNumber;
private Handler handler;
private Animation wrongAnswerAnimation;
private LinearLayout animalQuizLinearLayout;
private TextView txtQuestionNumber;
private ImageView imgAnimal;
private LinearLayout[] rowsOfGuessButtonsInAnimalQuiz;
private TextView txtAnswer;
public MainActivityFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_main, container, false);
allAnimalsNameList = new ArrayList<>();
animalNamesQuizList = new ArrayList<>();
secureRandomNumber = new SecureRandom();
handler = new Handler();
wrongAnswerAnimation = AnimationUtils.loadAnimation(getActivity(), R.anim.wrong_animation);
wrongAnswerAnimation.setRepeatCount(1);
animalQuizLinearLayout = view.findViewById(R.id.animalQuizLinearLayout);
txtQuestionNumber = view.findViewById(R.id.txtQuestionNumber);
imgAnimal = view.findViewById(R.id.imgAnimal);
rowsOfGuessButtonsInAnimalQuiz = new LinearLayout[3];
rowsOfGuessButtonsInAnimalQuiz[0] = view.findViewById(R.id.firstRowLinearLayout);
rowsOfGuessButtonsInAnimalQuiz[1] = view.findViewById(R.id.secondRowLinearLayout);
rowsOfGuessButtonsInAnimalQuiz[2] = view.findViewById(R.id.thirdRowLinearLayout);
txtAnswer = view.findViewById(R.id.txtAnswer);
for (LinearLayout row : rowsOfGuessButtonsInAnimalQuiz) {
for (int column = 0; column < row.getChildCount(); column++) {
Button btnGuess = (Button) row.getChildAt(column);
btnGuess.setOnClickListener(btnGuessListener);
btnGuess.setTextSize(24);
}
}
txtQuestionNumber.setText(getString(R.string.question_text, 1, NUMBER_OF_ANIMALS_INCLUDED_IN_QUIZ));
// getString is extends fragment...........
return view;
}
private View.OnClickListener btnGuessListener = new View.OnClickListener() {
@Override
public void onClick(View view) {
Button btnGuess = ((Button) view);
String guessValue = btnGuess.getText().toString();
String answerValue = getTheExactAnimalName(correctAnimalsAnswer);
++numberOfAllGuesses;
if (guessValue.equals(answerValue)) {
++numberOfRightAnswers;
txtAnswer.setText(answerValue + " ! " + " RIGHT");
disableQuizGuessButton();
if (numberOfRightAnswers == NUMBER_OF_ANIMALS_INCLUDED_IN_QUIZ) {
MainActivity mainActivity = new MainActivity();
mainActivity.showDialog();
} else {
handler.postDelayed(new Runnable() {
@Override
public void run() {
animateAnimalQuiz(true);
}
}, 1000); //1000 milliseconds for 1 second delay.......
}
} else {
imgAnimal.startAnimation(wrongAnswerAnimation);
txtAnswer.setText(R.string.wrong_answer_message);
btnGuess.setEnabled(false);
}
}
};
public static String getTheExactAnimalName(String animalName) {
return animalName.substring(animalName.indexOf('-') + 1).replace('_', ' ');
}// this method changes the actual name of image for example removes or starts after tame_animal- through index of method
// and after that removes _ between the names of animals...........
private void disableQuizGuessButton() {
for (int row = 0; row < numberOfAnimalGuessRows; row++) {
LinearLayout guessRowLinearLayout = rowsOfGuessButtonsInAnimalQuiz[row];
for (int buttonIndex = 0; buttonIndex < guessRowLinearLayout.getChildCount(); buttonIndex++) {
guessRowLinearLayout.getChildAt(buttonIndex).setEnabled(false);
}
}
}
public void resetAnimalQuiz() {
AssetManager assets = getActivity().getAssets();
allAnimalsNameList.clear();
try {
for (String animalType : animalTypesInQuiz) {
String[] animalImagePathsInQuiz = assets.list(animalType);
for (String animalImagePathInQuiz : animalImagePathsInQuiz) {
allAnimalsNameList.add(animalImagePathInQuiz.replace(".png", ""));
}
}
} catch (IOException e) {
Log.e("AnimalQuiz", "Error", e);
}
numberOfRightAnswers = 0; // this variable holds the right guesses must be 0 because we reset the game.
numberOfAllGuesses = 0; // this variable holds no. of all guesses whether it is right or wrong have to be 0.
animalNamesQuizList.clear(); // this variable holds randomly generated quiz paths must be 0 to generate new paths......
int counter = 1;
int numberOfAvailableAnimal = allAnimalsNameList.size();// this variable holds number of available animals or the size or length of paths
while (counter <= NUMBER_OF_ANIMALS_INCLUDED_IN_QUIZ) {
int randomIndex = secureRandomNumber.nextInt(numberOfAvailableAnimal);
String animalImageName = allAnimalsNameList.get(randomIndex);
if (!animalNamesQuizList.contains(animalImageName)) {
animalNamesQuizList.add(animalImageName);
++counter;
}
}
showNextAnimal();
}
private void animateAnimalQuiz(boolean animateOutAnimalImage) {
if (numberOfRightAnswers == 0) {
return;
}
int xTopLeft = 0;
int yTopLeft = 0;
int xBottomRight = animalQuizLinearLayout.getLeft() + animalQuizLinearLayout.getRight();
int yBottomRight = animalQuizLinearLayout.getTop() + animalQuizLinearLayout.getBottom();
//Here is max value for radius
int radius = Math.max(animalQuizLinearLayout.getWidth(), animalQuizLinearLayout.getHeight());
Animator animator;
if (animateOutAnimalImage) {
animator = ViewAnimationUtils.createCircularReveal(animalQuizLinearLayout, xBottomRight, yBottomRight, radius, 0);
animator.addListener(new Animator.AnimatorListener() {
@Override
public void onAnimationStart(Animator animation) {
}
@Override
public void onAnimationEnd(Animator animation) {
showNextAnimal();
}
@Override
public void onAnimationCancel(Animator animation) {
}
@Override
public void onAnimationRepeat(Animator animation) {
}
});
} else {
animator = ViewAnimationUtils.createCircularReveal(animalQuizLinearLayout, xTopLeft, yTopLeft, 0, radius);
}
animator.setDuration(700);
animator.start();
}
private void showNextAnimal() {
String nextAnimalImageName = animalNamesQuizList.remove(0);
correctAnimalsAnswer = nextAnimalImageName;
txtAnswer.setText("");
txtQuestionNumber.setText(getString(R.string.question_text, (numberOfRightAnswers + 1), NUMBER_OF_ANIMALS_INCLUDED_IN_QUIZ));
String animalType = nextAnimalImageName.substring(0, nextAnimalImageName.indexOf("-")); // it holds the animal type whether it is
// Tame animal or Wild Animal
AssetManager assets = getActivity().getAssets();
try (InputStream stream = assets.open(animalType + "/" + nextAnimalImageName + ".png")) {
Drawable animalImage = Drawable.createFromStream(stream, nextAnimalImageName);
imgAnimal.setImageDrawable(animalImage);
animateAnimalQuiz(false);
} catch (IOException e) {
Log.e("AnimalQuiz", "There is an Error Getting" + nextAnimalImageName, e);
}
Collections.shuffle(allAnimalsNameList); // this method is a predefined method in java which helps to shuffle the list of data
int correctAnimalNameIndex = allAnimalsNameList.indexOf(correctAnimalsAnswer);
String correctAnimalName = allAnimalsNameList.remove(correctAnimalNameIndex);
allAnimalsNameList.add(correctAnimalName);
for (int row = 0; row < numberOfAnimalGuessRows; row++) {
for (int column = 0; column < rowsOfGuessButtonsInAnimalQuiz[row].getChildCount(); column++) {
Button btnGuess = (Button) rowsOfGuessButtonsInAnimalQuiz[row].getChildAt(column);
btnGuess.setEnabled(true);
String animalImageName = allAnimalsNameList.get((row * 2) + column);
btnGuess.setText(getTheExactAnimalName(animalImageName));
}
}
int row = secureRandomNumber.nextInt(numberOfAnimalGuessRows);
int column = secureRandomNumber.nextInt(2);
LinearLayout randomRow = rowsOfGuessButtonsInAnimalQuiz[row];
String correctAnimalImageName = getTheExactAnimalName(correctAnimalsAnswer);
((Button) randomRow.getChildAt(column)).setText(correctAnimalImageName);
}
public void modifyAnimalGuessRows(SharedPreferences sharedPreferences){
final String NUMBER_OF_GUESS_OPTION = sharedPreferences.getString(GUESSES,null);
numberOfAnimalGuessRows = Integer.parseInt(NUMBER_OF_GUESS_OPTION)/2;
for (LinearLayout horizontalLinearLayout : rowsOfGuessButtonsInAnimalQuiz){
horizontalLinearLayout.setVisibility(View.GONE);
}
for (int row = 0; row < numberOfAnimalGuessRows; row++){
rowsOfGuessButtonsInAnimalQuiz[row].setVisibility(View.VISIBLE);
}
}
public void modifyTypeofAnimals(SharedPreferences sharedPreferences){
animalTypesInQuiz = sharedPreferences.getStringSet(ANIMALS_TYPE,null);
}
public void modifyQuizFont(SharedPreferences sharedPreferences){
String fontStringValue = sharedPreferences.getString(QUIZ_FONT,null);
switch (fontStringValue){
case "Chunkfive.otf":
for (LinearLayout row : rowsOfGuessButtonsInAnimalQuiz){
for (int column = 0; column < row.getChildCount(); column++) {
Button button = (Button) row.getChildAt(column);
button.setTypeface(chunkFive);
}
}
break;
case "Azkia demo.otf":
for (LinearLayout row : rowsOfGuessButtonsInAnimalQuiz){
for (int column = 0; column < row.getChildCount(); column++) {
Button button = (Button) row.getChildAt(column);
button.setTypeface(azkiaDemo);
}
}
break;
case "FontleroyBrown.otf":
for (LinearLayout row : rowsOfGuessButtonsInAnimalQuiz){
for (int column = 0; column < row.getChildCount(); column++) {
Button button = (Button) row.getChildAt(column);
button.setTypeface(fontleroyBrown);
}
}
break;
case "Haunted Eyes.otf":
for (LinearLayout row : rowsOfGuessButtonsInAnimalQuiz){
for (int column = 0; column < row.getChildCount(); column++) {
Button button = (Button) row.getChildAt(column);
button.setTypeface(hauntedEyes);
}
}
break;
case "Knight Brush Demo.otf":
for (LinearLayout row : rowsOfGuessButtonsInAnimalQuiz){
for (int column = 0; column < row.getChildCount(); column++) {
Button button = (Button) row.getChildAt(column);
button.setTypeface(knightBrushDemo);
}
}
break;
case "Wonderbar Demo.otf":
for (LinearLayout row : rowsOfGuessButtonsInAnimalQuiz){
for (int column = 0; column < row.getChildCount(); column++) {
Button button = (Button) row.getChildAt(column);
button.setTypeface(wonderbarDemo);
}
}
break;
}
}
public void modifyBackgroundColor(SharedPreferences sharedPreferences){
String backgroundColor = sharedPreferences.getString(QUIZ_BACKGROUND_COLOR,null);
switch (backgroundColor){
case "White":
animalQuizLinearLayout.setBackgroundColor(Color.WHITE);
for (LinearLayout row : rowsOfGuessButtonsInAnimalQuiz){
for (int column = 0; column < row.getChildCount(); column++){
Button button = (Button) row.getChildAt(column);
button.setBackgroundColor(Color.rgb(34,167,240));
button.setTextColor(Color.WHITE);
}
}
txtQuestionNumber.setTextColor(Color.BLACK);
txtAnswer.setTextColor(Color.rgb(34,167,240));
break;
case "Black":
animalQuizLinearLayout.setBackgroundColor(Color.BLACK);
for (LinearLayout row : rowsOfGuessButtonsInAnimalQuiz){
for (int column = 0; column < row.getChildCount(); column++){
Button button = (Button) row.getChildAt(column);
button.setBackgroundColor(Color.rgb(247,202,24));
button.setTextColor(Color.BLACK);
}
}
txtQuestionNumber.setTextColor(Color.WHITE);
txtAnswer.setTextColor(Color.WHITE);
break;
case "Green":
animalQuizLinearLayout.setBackgroundColor(Color.rgb(38,166,91));
for (LinearLayout row : rowsOfGuessButtonsInAnimalQuiz){
for (int column = 0; column < row.getChildCount(); column++){
Button button = (Button) row.getChildAt(column);
button.setBackgroundColor(Color.rgb(34,167,240));
button.setTextColor(Color.WHITE);
}
}
txtQuestionNumber.setTextColor(Color.rgb(247,202,24));
txtAnswer.setTextColor(Color.WHITE);
break;
case "Yellow":
animalQuizLinearLayout.setBackgroundColor(Color.rgb(247,202,24));
for (LinearLayout row : rowsOfGuessButtonsInAnimalQuiz){
for (int column = 0; column < row.getChildCount(); column++){
Button button = (Button) row.getChildAt(column);
button.setBackgroundColor(Color.BLACK);
button.setTextColor(Color.WHITE);
}
}
txtQuestionNumber.setTextColor(Color.BLACK);
txtAnswer.setTextColor(Color.BLACK);
break;
case "Red":
animalQuizLinearLayout.setBackgroundColor(Color.rgb(240,52,52));
for (LinearLayout row : rowsOfGuessButtonsInAnimalQuiz){
for (int column = 0; column < row.getChildCount(); column++){
Button button = (Button) row.getChildAt(column);
button.setBackgroundColor(Color.rgb(34,167,240));
button.setTextColor(Color.WHITE);
}
}
txtQuestionNumber.setTextColor(Color.WHITE);
txtAnswer.setTextColor(Color.WHITE);
break;
case "Blue":
animalQuizLinearLayout.setBackgroundColor(Color.rgb(34,167,240));
for (LinearLayout row : rowsOfGuessButtonsInAnimalQuiz){
for (int column = 0; column < row.getChildCount(); column++){
Button button = (Button) row.getChildAt(column);
button.setBackgroundColor(Color.rgb(240,52,52));
button.setTextColor(Color.WHITE);
}
}
txtQuestionNumber.setTextColor(Color.WHITE);
txtAnswer.setTextColor(Color.WHITE);
break;
}
}
}
import android.app.AlertDialog;
import android.app.Dialog;
import android.app.DialogFragment;
import android.content.DialogInterface;
import android.os.Bundle;
import static com.example.narayanmaity.app61animal_quiz.MainActivityFragment.numberOfAllGuesses;
/**
* Created by Narayan Maity on 12/14/2017.
*/
public class ExampleDialog extends DialogFragment {
MainActivityFragment myAnimalQuizFragment;
@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
builder.setMessage(getString(R.string.results_string_value, numberOfAllGuesses,
(1000 / (double) numberOfAllGuesses)));
builder.setPositiveButton(R.string.result_animal_quiz, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
myAnimalQuizFragment.resetAnimalQuiz();
}
});
return builder.create();
}
}
答案 0 :(得分：0)
问题在于此行。从代码
移除下面一行 MainActivity mainActivity = new MainActivity();
mainActivity.showDialog();
您永远不会使用new运算符创建Activity的实例。它的android Component类使用Intent自动初始化。 android中的所有活动必须经历一个生命周期，以便它们附加有效的上下文。阅读Activity。
解决此问题的方法。
if(getActivity()!=null){
((MainActivity)getActivity()).showDialog()
}
您在评论中提到的新问题。
您永远不会指定 myAnimalQuizFragment ，因此无论如何它都会为您提供NullPointerException。从您的MainActivity访问它。
((MainActivity)getActivity()).myAnimalQuizFragment.resetAnimalQuiz();
在MainActivity中将myAnimalQuizFragment设为公共。