Android学习第4天

代码

QuizActivaty.java

package com.bignerdranch.android.geoquiz;import android.os.Bundle;import android.support.v7.app.AppCompatActivity;import android.util.Log;import android.view.View;import android.widget.Button;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 Button mTrueButton;    private Button mFalseButton;    private Button mNextButton;    private TextView mQuestionTextView;    private Question[] mQuestionBank = new Question[] {            new Question(R.string.question_australia, true),            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),    };    private int mCurrentIndex = 0;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        Log.d(TAG, "onCreate(Bundle) called");        setContentView(R.layout.activity_quiz);        if (savedInstanceState != null) {            mCurrentIndex = savedInstanceState.getInt(KEY_INDEX, 0);        }        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 v) {                checkAnswer(true);            }        });        mFalseButton = (Button) findViewById(R.id.false_button);        mFalseButton.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                checkAnswer(false);            }        });        mNextButton = (Button) findViewById(R.id.next_button);        mNextButton.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                mCurrentIndex = (mCurrentIndex + 1) % mQuestionBank.length;                updateQuestion();            }        });        updateQuestion();    }    @Override    protected void onStart() {        super.onStart();        Log.d(TAG, "onStart() called");    }    @Override    protected void onResume() {        super.onResume();        Log.d(TAG, "onResume() called");    }    @Override    protected void onPause() {        super.onPause();        Log.d(TAG, "onPause() called");    }    @Override    protected void onSaveInstanceState(Bundle savedInstanceState) {        super.onSaveInstanceState(savedInstanceState);        Log.i(TAG, "onSaveInstanceState");        savedInstanceState.putInt(KEY_INDEX, mCurrentIndex);    }    @Override    protected void onStop() {        super.onStop();        Log.d(TAG, "onStop() called");    }    @Override    protected void onDestroy() {        super.onDestroy();        Log.d(TAG, "onDestroy() called");    }    private void updateQuestion() {        int question = mQuestionBank[mCurrentIndex].getTextResId();        mQuestionTextView.setText(question);    }    private void checkAnswer(boolean userPressedTrue) {        boolean answerIsTrue = mQuestionBank[mCurrentIndex].isAnswerTrue();        int messageResId = 0;        if (userPressedTrue == answerIsTrue) {            messageResId = R.string.correct_toast;        } else {            messageResId = R.string.incorrect_toast;        }        Toast.makeText(this, messageResId, Toast.LENGTH_SHORT)                .show();    }}