所以，我现在正在通过Android上的大书呆子牧场工作，我已经完成了大部分第一个应用程序，很有趣，无论如何，但我遇到的问题是在实施一个作弊按钮之后对于测验，当我从作弊屏幕返回时，我的真假按钮不再起作用。
肯定有点击注册，它只是停止做任何事情。
还有一个错误，如果我将其水平转动，整个应用程序崩溃，但我会发布这两个活动的代码，看看我们得到了什么。
private void checkAnswer(boolean userPressedTrue){
boolean answerIsTrue = mQuestionBank[mCurrentIndex].isTrueQuestion();
int messageResId=0;
if(mIsCheater){
messageResId=R.string.judgement_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(data==null){
return;
}
mIsCheater=data.getBooleanExtra(CheatActivity.EXTRA_ANSWER_SHOWN, false);
}
@Override
protected void onCreate(Bundle savedInstanceState) {
if(savedInstanceState!=null){
mCurrentIndex=savedInstanceState.getInt(KEY_INDEX, 0);
}
super.onCreate(savedInstanceState);
Log.d(TAG, "onCreate(Bundle) called");
setContentView(R.layout.activity_quiz);
mCheatButton=(Button)findViewById(R.id.cheat_button);
mCheatButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent i = new Intent(QuizActivity.this, CheatActivity.class);
boolean answerIsTrue=mQuestionBank[mCurrentIndex].isTrueQuestion();
i.putExtra(CheatActivity.EXTRA_ANSWER_IS_TRUE, answerIsTrue);
startActivityForResult(i,0);
}
});
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);
}
});
@Override
public void onSaveInstanceState(Bundle savedInstanceState){
super.onSaveInstanceState(savedInstanceState);
Log.i(TAG, "onSaveInstanceState");
savedInstanceState.putInt(KEY_INDEX, mCurrentIndex);
}
package com.example.geoquiz;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
public class CheatActivity extends Activity {
private boolean mAnswerIsTrue;
public static final String EXTRA_ANSWER_IS_TRUE = "com.example.geoquiz.answer_is_true";
public static final String EXTRA_ANSWER_SHOWN="com.example.geoquiz.answer_shown";
private TextView mAnswerTextView;
private Button mShowAnswer;
private void setAnswerShownResult(boolean isAnswerShown){
Intent data = new Intent();
data.putExtra(EXTRA_ANSWER_SHOWN, isAnswerShown);
setResult(RESULT_OK, data);
}
@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.answerTextView);
setAnswerShownResult(false);
mShowAnswer=(Button)findViewById(R.id.showAnswerButton);
mShowAnswer.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (mAnswerIsTrue) {
mAnswerTextView.setText(R.string.true_button);
} else {
mAnswerTextView.setText(R.string.false_button);
}
setAnswerShownResult(true);
}
});
}
}
在检查logcat时，我发现了一个关于水平方向问题的空指针异常。
08-18 18:39:30.398: E/AndroidRuntime(24316): FATAL EXCEPTION: main
08-18 18:39:30.398: E/AndroidRuntime(24316): Process: com.example.geoquiz, PID: 24316
08-18 18:39:30.398: E/AndroidRuntime(24316): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.geoquiz/com.example.geoquiz.QuizActivity}: java.lang.NullPointerException
08-18 18:39:30.398: E/AndroidRuntime(24316): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2198)
08-18 18:39:30.398: E/AndroidRuntime(24316): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2257)
08-18 18:39:30.398: E/AndroidRuntime(24316): at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:3805)
08-18 18:39:30.398: E/AndroidRuntime(24316): at android.app.ActivityThread.access$900(ActivityThread.java:139)
08-18 18:39:30.398: E/AndroidRuntime(24316): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1216)
08-18 18:39:30.398: E/AndroidRuntime(24316): at android.os.Handler.dispatchMessage(Handler.java:102)
08-18 18:39:30.398: E/AndroidRuntime(24316): at android.os.Looper.loop(Looper.java:136)
08-18 18:39:30.398: E/AndroidRuntime(24316): at android.app.ActivityThread.main(ActivityThread.java:5086)
08-18 18:39:30.398: E/AndroidRuntime(24316): at java.lang.reflect.Method.invokeNative(Native Method)
08-18 18:39:30.398: E/AndroidRuntime(24316): at java.lang.reflect.Method.invoke(Method.java:515)
08-18 18:39:30.398: E/AndroidRuntime(24316): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
08-18 18:39:30.398: E/AndroidRuntime(24316): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
08-18 18:39:30.398: E/AndroidRuntime(24316): at dalvik.system.NativeStart.main(Native Method)
08-18 18:39:30.398: E/AndroidRuntime(24316): Caused by: java.lang.NullPointerException
08-18 18:39:30.398: E/AndroidRuntime(24316): at com.example.geoquiz.QuizActivity.onCreate(QuizActivity.java:116)
08-18 18:39:30.398: E/AndroidRuntime(24316): at android.app.Activity.performCreate(Activity.java:5248)
08-18 18:39:30.398: E/AndroidRuntime(24316): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1110)
08-18 18:39:30.398: E/AndroidRuntime(24316): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2162)
08-18 18:39:30.398: E/AndroidRuntime(24316): ... 12 more
答案 0 :(得分：0)
使用logcat.v诊断缺少按钮功能，并在logcat中打印mIsCheater的布尔值。在确定布尔值打印之后，以及在回答检查点时，我重写了checkAnswer逻辑以检查实际值是什么 - 之前的问题是在此代码中它只是检查如果变量存在，似乎。
无论如何，固定代码是
private void checkAnswer(boolean userPressedTrue){
boolean answerIsTrue = mQuestionBank[mCurrentIndex].isTrueQuestion();
int messageResId=0;
if(mIsCheater==true){
messageResId=R.string.judgement_toast;
}
else if (userPressedTrue==answerIsTrue) {
messageResId=R.string.correct_toast;
} else {
messageResId=R.string.incorrect_toast;
}
Log.v(TAG, Boolean.toString(mIsCheater));
Toast.makeText(this, messageResId, Toast.LENGTH_SHORT)
.show();
}
横向问题是由于我有横向布局而没有在xml中声明作弊按钮。