java - 无法显示 Cheat Toast 并且按下后退按钮时应用程序不会返回上一个屏幕

Question

我正在关注 The Big Nerd Ranch book for Android, 2nd edition 中的一些编码教程。我已遵循所有示例，但无法在 QuizActivity.java 文件中显示judgement_toast。此外，当按下应用程序时，不会返回主问题屏幕。

请查看下面所有 3 个类中的所有代码......非常感谢任何帮助。

package uk.co.sbworrallgmail.geoquiz;

import android.app.Activity;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ImageButton;
import android.widget.TextView;
import android.widget.Toast;

    public class QuizActivity extends AppCompatActivity {

    private static final String TAG = "QuizActivity";
    private static final String KEY_INDEX = "index";

    private static final int REQUEST_CODE_CHEAT = 0;

    private boolean mIsCheater;

    private Button mTrueButton;
    private Button mFalseButton;
    private Button mCheatButton;

    private ImageButton mNextButton;
    private ImageButton mPrevButton;

    private TextView mQuestionTextView;

    private int mCurrentIndex = 0;

    private Question[] mQuestionsBank = new Question[]{
            new Question(R.string.question_oceans, true),
            new Question(R.string.question_mideast, false),
            new Question(R.string.question_africa, false),
            new Question(R.string.question_americas, true),
            new Question(R.string.question_asia, true),
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        Log.d(TAG, "onCreate(Bundle) called");
        setContentView(R.layout.activity_quiz);

        mQuestionTextView = (TextView) findViewById(R.id.question_text_view);

        mTrueButton = (Button) findViewById(R.id.true_button);
        mTrueButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                checkAnswer(true);
            }
        });
        mFalseButton = (Button) findViewById(R.id.false_button);
        mFalseButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                checkAnswer(false);
            }
        });
        mNextButton = (ImageButton) findViewById(R.id.next_button);
        mNextButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                mCurrentIndex = (mCurrentIndex + 1) % mQuestionsBank.length;
                mIsCheater = false;
                updateQuestion();
            }
        });
        mPrevButton = (ImageButton) findViewById(R.id.prev_button);
        mPrevButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                mCurrentIndex = (mCurrentIndex -1) % mQuestionsBank.length;
                updateQuestion();
            }
        });
        mCheatButton = (Button) findViewById(R.id.cheat_button);
        mCheatButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                //  Start CheatActivity
                boolean answerIsTrue = mQuestionsBank[mCurrentIndex].isAnswerTrue();
                Intent intent = CheatActivity.newIntent(QuizActivity.this, answerIsTrue);
                startActivityForResult(intent, REQUEST_CODE_CHEAT);
            }
        });
        mQuestionTextView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                mCurrentIndex = (mCurrentIndex + 1) % mQuestionsBank.length;
                updateQuestion();
            }
        });
        if (savedInstanceState != null) {
            mCurrentIndex = savedInstanceState.getInt(KEY_INDEX, 0);
        }
        updateQuestion();
    }

    @Override
    public void onSaveInstanceState(Bundle savedInstanceState) {
        super.onSaveInstanceState(savedInstanceState);
        Log.i(TAG, "onSaveInstanceState");
        savedInstanceState.putInt(KEY_INDEX, mCurrentIndex);
    }

    @Override
    public void onStart() {
        super.onStart();
        Log.d(TAG, "onStart() called");
    }

    @Override
    public void onPause() {
        super.onPause();
        Log.d(TAG, "onPause() called");
    }
    @Override

    public void onResume() {
        super.onResume();
        Log.d(TAG, "onResume() called");
    }

    @Override
    public void onStop() {
        super.onStop();
        Log.d(TAG, "onStop() called");
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        Log.d(TAG, "onDestroy called");
    }

    private void updateQuestion() {
        int question = mQuestionsBank[mCurrentIndex].getTextResId();
        mQuestionTextView.setText(question);
    }

    private void checkAnswer(boolean userPressedTrue) {
        boolean answerIsTrue = mQuestionsBank[mCurrentIndex].isAnswerTrue();

        int messageResId = 0;

        if (mIsCheater) {
            messageResId = R.string.judgment_toast;
        } else {
            if (userPressedTrue == answerIsTrue) {
                messageResId = R.string.correct_toast;
            } else {
                messageResId = R.string.incorrect_toast;
            }
        }
        Toast.makeText(this, messageResId, Toast.LENGTH_SHORT).show();
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (resultCode != Activity.RESULT_OK) {
            return;
        }
        if (requestCode == REQUEST_CODE_CHEAT) {
            if (data == null) {
                return;
            }
            mIsCheater = CheatActivity.wasAnswerShown(data);
        }
    }
}

和我的 CheatActivity.java 文件

package uk.co.sbworrallgmail.geoquiz;

import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class CheatActivity extends AppCompatActivity {

    private static final String EXTRA_ANSWER_IS_TRUE = "uk.co.sbworrallgmail.geoquiz.answer_is_true";
    private static final String EXTRA_ANSWER_IS_SHOWN = "uk.co.sbworrallgmail.geoquiz.answer_is_shown";

    private boolean mAnswerIsTrue;

    private TextView mAnswerTextView;

    private Button mShowAnswer;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_cheat);

        mAnswerIsTrue = getIntent().getBooleanExtra(EXTRA_ANSWER_IS_TRUE, false);

        mAnswerTextView = (TextView) findViewById(R.id.answer_Text_View);

        mShowAnswer = (Button) findViewById(R.id.show_Answer_Button);
        mShowAnswer.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if (mAnswerIsTrue) {
                    mAnswerTextView.setText(R.string.true_button);
                } else {
                    mAnswerTextView.setText(R.string.false_button);
                }
                setAnswerShownResult(true);
            }
        });
    }

    public static Intent newIntent(Context packageContext, boolean answerIsTrue) {
        Intent intent = new Intent(packageContext, CheatActivity.class);
        intent.putExtra(EXTRA_ANSWER_IS_TRUE, answerIsTrue);
        return intent;
    }

    private void setAnswerShownResult(boolean isAnswerShown) {
        Intent data = new Intent();
        data.putExtra(EXTRA_ANSWER_IS_SHOWN, isAnswerShown);
        setResult(RESULT_OK, data);
    }

    public static boolean wasAnswerShown(Intent result) {
        return result.getBooleanExtra(EXTRA_ANSWER_IS_SHOWN, false);
    }

}

和我的 Question.java 文件

package uk.co.sbworrallgmail.geoquiz;

public class Question {

    private int mTextResId;

    private boolean mAnswerTrue;

    public void setTextResId(int textResId) {
        mTextResId = textResId;
    }

    public void setAnswerTrue(boolean answerTrue) {
        mAnswerTrue = answerTrue;
    }

    public int getTextResId() {
        return mTextResId;
    }

    public boolean isAnswerTrue() {
        return mAnswerTrue;
    }

    public Question(int textResId, boolean answerTrue) {
        mTextResId = textResId;
        mAnswerTrue = answerTrue;
    }
}

和我的清单文件按要求：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="uk.co.sbworrallgmail.geoquiz">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity
            android:name=".QuizActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity
            android:name=".CheatActivity"
            android:label="@string/title_activity_cheat"
            android:theme="@style/AppTheme.NoActionBar">
        </activity>
    </application>

</manifest>

标签： javaandroid

Answer 1

您如何为后退按钮设置活动？显示您的清单。

然而...

您的 toast 很可能不起作用，因为 Toast 为第二个参数采用 String 值，您给它一个 int....

试试这个。

private void checkAnswer(boolean userPressedTrue) {
        boolean answerIsTrue = mQuestionsBank[mCurrentIndex].isAnswerTrue();

        String messageResId = "";

        if (mIsCheater) {
            messageResId = getResources().getString(R.string.judgment_toast);
        } else {
            if (userPressedTrue == answerIsTrue) {
                messageResId = getResources().getString(R.string.correct_toast);
            } else {
                messageResId = getResources().getString(R.string.incorrect_toast);
            }
        }
        Toast.makeText(QuizActivity.this, messageResId, Toast.LENGTH_SHORT).show();
    }