Uygulama, bir düğmeye bastığınızda çöküyor, bu başka bir etkinlik başlatıyor

Question

Başlık gibi, Etkinliği değiştirmek için düğmeye bastığımda Uygulamam çöküyor diyor. Tutulma sırasında hata göstermez ve başlangıçta açılır, ancak düğmeye bastığımda kapanır. Başlangıçta Uygulama hiç açılmıyordu ama onClick() içerisindeki değişkenleri açmasına izin verdim. İlk faaliyet

Bildirim

<application 
    android:allowBackup="true" 
    android:icon="@drawable/globe" 
    android:label="@string/app_name" 
    android:theme="@style/AppTheme" > 
    <activity 
     android:name="com.example.geoquizlab1solution.QuizActivity" 
     android:label="@string/app_name" > 
     <intent-filter> 
      <action android:name="android.intent.action.MAIN" /> 

      <category android:name="android.intent.category.LAUNCHER" /> 
     </intent-filter> 
    </activity> 
    <activity android:screenOrientation="unspecified" android:name="com.example.geoquizlab1solution.SportsQuiz"/> 
    </application> 

Sınıf ActivityQuiz.java:

package com.example.geoquizlab1solution; 

import android.app.Activity; 
import android.content.Intent; 
import android.content.SharedPreferences; 
import android.os.Bundle; 
import android.preference.PreferenceManager; 
import android.view.Menu; 
import android.view.View; 
import android.widget.Button; 
import android.widget.ImageButton; 
import android.widget.TextView; 
import android.widget.Toast; 

public class QuizActivity extends Activity { 

private Button mTrueButton; 
private Button mFalseButton; 
private ImageButton mNextButton; 
private ImageButton mPreviousButton; 
private TextView mQuestionTextView; 
private Button mResetButton; 
private Button mSportsButton; 
private Button mGeoButton; 
//private Button mMusicButton; 
private int counter = 0; 


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


private int mCurrentIndex=0; 

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

private void checkAnswer(boolean userPressedTrue) { 
    boolean answerIsTrue = mQuestionBank[mCurrentIndex].isTrueQuestion(); 
    int messageResId = 0; 

    SharedPreferences app_preferences = 
      PreferenceManager.getDefaultSharedPreferences(this); 

    if (userPressedTrue == answerIsTrue) { 
     messageResId = R.string.correct_toast; 
     counter++; 

    } 
     else { 
      messageResId = R.string.incorrect_toast; 
     } 
    SharedPreferences.Editor editor = app_preferences.edit(); 
     editor.putInt("count", counter); 
    Toast.makeText(this, messageResId, Toast.LENGTH_SHORT).show(); 
    Toast.makeText(this,"Score:" + counter, Toast.LENGTH_SHORT).show(); 
    editor.commit(); 
     } 

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


    mGeoButton = (Button)findViewById(R.id.geo_button); 
    mGeoButton.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View v) { 
      counter = 0; 
      Toast.makeText(getApplicationContext(), "Score: 0", 
        Toast.LENGTH_SHORT).show(); 
      mCurrentIndex = 0; 
      updateQuestion(); 
     } 
    }); 

    mSportsButton = (Button)findViewById(R.id.sports_button); 
    mSportsButton.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View v) { 
      final Intent intent1 = new Intent(QuizActivity.this, SportsQuiz.class); 
      if (intent1 != null) { 
       startActivity(intent1); 
      } 
     } 
    }); 

    /* mMusicButton = (Button)findViewById(R.id.music_button); 
    mMusicButton.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View v) { 
      Intent intent = new Intent(this, MusicQuiz.java); 
     } 
    });*/ 

    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); 
      } 
    }); 
    mQuestionTextView = (TextView)findViewById(R.id.question_text_view); 
    ((View) mQuestionTextView) .setOnClickListener(new View.OnClickListener() { 

     @Override 
     public void onClick(View v) { 
      mCurrentIndex = (mCurrentIndex + 1) % mQuestionBank.length; 
      updateQuestion(); 
     } 
    }); 
    updateQuestion(); 

    mPreviousButton = (ImageButton)findViewById(R.id.previous_button); 
    ((View) mPreviousButton) .setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View v) { 
       if (mCurrentIndex != 0) { 
        mCurrentIndex = (mCurrentIndex - 1) % mQuestionBank.length; 
       updateQuestion(); 
       } 
       else { 
        mCurrentIndex = (mCurrentIndex + 4) % mQuestionBank.length; 
       } 
     } 
    }); 
    updateQuestion(); 


    mNextButton = (ImageButton)findViewById(R.id.next_button); 
    ((View) mNextButton).setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View v) { 

      mCurrentIndex = (mCurrentIndex + 1) % mQuestionBank.length; 
      updateQuestion(); 
     } 
     }); 
    updateQuestion(); 

    mResetButton = (Button)findViewById(R.id.reset_button); 
    ((View) mResetButton).setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View v) { 
      counter = 0; 
      Toast.makeText(getApplicationContext(), "Score: 0", 
        Toast.LENGTH_SHORT).show(); 
      mCurrentIndex = 0; 
      updateQuestion(); 
     } 
    }); 
} 




@Override 
public boolean onCreateOptionsMenu(Menu menu) { 
    // Inflate the menu; this adds items to the action bar if it is present. 
    getMenuInflater().inflate(R.menu.activity_quiz, menu); 
    return true; 
} 

}

SportsQuiz.java:

package com.example.geoquizlab1solution; 

import android.app.Activity; 
import android.content.Intent; 
import android.content.SharedPreferences; 
import android.os.Bundle; 
import android.preference.PreferenceManager; 
import android.view.Menu; 
import android.view.View; 
import android.widget.Button; 
import android.widget.ImageButton; 
import android.widget.TextView; 
import android.widget.Toast; 


public class SportsQuiz extends Activity { 
private Button mTrueButton; 
private Button mFalseButton; 
private ImageButton mNextButton; 
private ImageButton mPreviousButton; 
private TextView mQuestionTextView; 
private Button mResetButton; 
private Button mSportsButton; 
private Button mGeoButton; 
//private Button mMusicButton; 
private int counter = 0; 
Intent intent1 = getIntent(); 
Intent intent = new Intent(this, SportsQuiz.class); 


private TrueFalse[] mQuestionBank = new TrueFalse[] { 
     new TrueFalse(R.string.question_baseball, true), 
     new TrueFalse(R.string.question_football, false), 
     new TrueFalse(R.string.question_basketball, false), 
     new TrueFalse(R.string.question_hockey, true), 
     new TrueFalse(R.string.question_soccer, true) 
}; 


private int mCurrentIndex=0; 

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

private void checkAnswer(boolean userPressedTrue) { 
    boolean answerIsTrue = mQuestionBank[mCurrentIndex].isTrueQuestion(); 
    int messageResId = 0; 

    SharedPreferences app_preferences = 
      PreferenceManager.getDefaultSharedPreferences(this); 

    if (userPressedTrue == answerIsTrue) { 
     messageResId = R.string.correct_toast; 
     counter++; 

    } 
     else { 
      messageResId = R.string.incorrect_toast; 
     } 
    SharedPreferences.Editor editor = app_preferences.edit(); 
     editor.putInt("count", counter); 
    Toast.makeText(this, messageResId, Toast.LENGTH_SHORT).show(); 
    Toast.makeText(this,"Score:" + counter, Toast.LENGTH_SHORT).show(); 
    editor.commit(); 
     } 
/** Called when the activity is first created. */ 
@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_quiz); 


    mGeoButton = (Button)findViewById(R.id.geo_button); 
    mGeoButton.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View v) { 
      counter = 0; 
      Toast.makeText(getApplicationContext(), "Score: 0", 
        Toast.LENGTH_SHORT).show(); 
      mCurrentIndex = 0; 
      updateQuestion(); 
     } 
    }); 

    mSportsButton = (Button)findViewById(R.id.sports_button); 
    mSportsButton.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View v) { 
      startActivity(intent1); 
     } 
    }); 

    /* mMusicButton = (Button)findViewById(R.id.music_button); 
    mMusicButton.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View v) { 
      Intent intent = new Intent(this, MusicQuiz.java); 
     } 
    }); */ 

    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); 
      } 
    }); 
    mQuestionTextView = (TextView)findViewById(R.id.question_text_view); 
    ((View) mQuestionTextView) .setOnClickListener(new View.OnClickListener() { 

     @Override 
     public void onClick(View v) { 
      mCurrentIndex = (mCurrentIndex + 1) % mQuestionBank.length; 
      updateQuestion(); 
     } 
    }); 
    updateQuestion(); 

    mPreviousButton = (ImageButton)findViewById(R.id.previous_button); 
    ((View) mPreviousButton) .setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View v) { 
       if (mCurrentIndex != 0) { 
        mCurrentIndex = (mCurrentIndex - 1) % mQuestionBank.length; 
       updateQuestion(); 
       } 
       else { 
        mCurrentIndex = (mCurrentIndex + 4) % mQuestionBank.length; 
       } 
     } 
    }); 
    updateQuestion(); 


    mNextButton = (ImageButton)findViewById(R.id.next_button); 
    ((View) mNextButton).setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View v) { 

      mCurrentIndex = (mCurrentIndex + 1) % mQuestionBank.length; 
      updateQuestion(); 
     } 
     }); 
    updateQuestion(); 

    mResetButton = (Button)findViewById(R.id.reset_button); 
    ((View) mResetButton).setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View v) { 
      counter = 0; 
      Toast.makeText(getApplicationContext(), "Score: 0", 
        Toast.LENGTH_SHORT).show(); 
      mCurrentIndex = 0; 
      updateQuestion(); 
     } 
    }); 
} 




@Override 
public boolean onCreateOptionsMenu(Menu menu) { 
    // Inflate the menu; this adds items to the action bar if it is present. 
    getMenuInflater().inflate(R.menu.activity_quiz, menu); 
    return true; 
} 

} Burada

kayıtları:

04-04 20:48:42.600: E/AndroidRuntime(25939): FATAL EXCEPTION: main 

04-04 20:48:42.600: E/AndroidRuntime(25939): Process: com.example.geoquizlab1solution, PID: 25939 

04-04 20:48:42.600: E/AndroidRuntime(25939): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.geoquizlab1solution/com.example.geoquizlab1solution.SportsQuiz}: java.lang.NullPointerException 

04-04 20:48:42.600: E/AndroidRuntime(25939): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2124) 

04-04 20:48:42.600: E/AndroidRuntime(25939): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2257) 

04-04 20:48:42.600: E/AndroidRuntime(25939): at android.app.ActivityThread.access$800(ActivityThread.java:139) 

04-04 20:48:42.600: E/AndroidRuntime(25939): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1210) 

04-04 20:48:42.600: E/AndroidRuntime(25939): at android.os.Handler.dispatchMessage(Handler.java:102) 

04-04 20:48:42.600: E/AndroidRuntime(25939): at android.os.Looper.loop(Looper.java:136) 

04-04 20:48:42.600: E/AndroidRuntime(25939): at android.app.ActivityThread.main(ActivityThread.java:5097) 

04-04 20:48:42.600: E/AndroidRuntime(25939): at java.lang.reflect.Method.invokeNative(Native Method) 

04-04 20:48:42.600: E/AndroidRuntime(25939): at java.lang.reflect.Method.invoke(Method.java:515) 

04-04 20:48:42.600: E/AndroidRuntime(25939): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785) 

04-04 20:48:42.600: E/AndroidRuntime(25939): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601) 

04-04 20:48:42.600: E/AndroidRuntime(25939): at dalvik.system.NativeStart.main(Native Method) 

04-04 20:48:42.600: E/AndroidRuntime(25939): Caused by: java.lang.NullPointerException 

04-04 20:48:42.600: E/AndroidRuntime(25939): at android.content.ContextWrapper.getPackageName(ContextWrapper.java:135) 

04-04 20:48:42.600: E/AndroidRuntime(25939): at android.content.ComponentName.<init>(ComponentName.java:77) 

04-04 20:48:42.600: E/AndroidRuntime(25939): at android.content.Intent.<init>(Intent.java:3823) 

04-04 20:48:42.600: E/AndroidRuntime(25939): at com.example.geoquizlab1solution.SportsQuiz.<init>(SportsQuiz.java:28) 

04-04 20:48:42.600: E/AndroidRuntime(25939): at java.lang.Class.newInstanceImpl(Native Method) 

04-04 20:48:42.600: E/AndroidRuntime(25939): at java.lang.Class.newInstance(Class.java:1208) 

04-04 20:48:42.600: E/AndroidRuntime(25939): at android.app.Instrumentation.newActivity(Instrumentation.java:1084) 

04-04 20:48:42.600: E/AndroidRuntime(25939): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2115) 

04-04 20:48:42.600: E/AndroidRuntime(25939): ... 11 more 

Answer 1

Size Niyet tanımlanan bir nesne atamak olamaz

yüzden onCreate ya da diğerleri gibi etkinlik yaşam döngüsü yöntemine Bu satırı koymak,

Basitçe = new

niyet onCreate yönteminde bu satırı yazmak Niyet (bu, SportsQuiz.class); intent1 = getIntent();