在Android片段中单击一个按钮的NullPointerException onClick

我对放置在片段中的按钮的onCLick方法有问题。它抛出了一个NullPointerException，我无法解决这个问题

IqDbHelper.java代码：

package com.example.scientia;
import java.util.ArrayList;
import java.util.List;
import com.example.scientia.Question;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class IqDbHelper extends SQLiteOpenHelper {

    private static final int DATABASE_VERSION = 1;
    // Database Name
    private static final String DATABASE_NAME = "iqQuiz";
    // tasks table name
    private static final String TABLE_QUEST = "quest";
    // tasks Table Columns names
    private static final String KEY_ID = "id";
    private static final String KEY_QUES = "question";
    private static final String KEY_ANSWER = "answer"; //correct option
    private static final String KEY_OPTA= "opta"; //option a
    private static final String KEY_OPTB= "optb"; //option b
    private static final String KEY_OPTC= "optc"; //option c
    private static final String KEY_OPTD= "optd"; //option d
    private SQLiteDatabase dbase;

    public IqDbHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }
    @Override
    public void onCreate(SQLiteDatabase db) {
        dbase=db;
        String sql = "CREATE TABLE IF NOT EXISTS " + TABLE_QUEST + " ( "
                + KEY_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " + KEY_QUES
                + " TEXT, " + KEY_ANSWER+ " TEXT, "+KEY_OPTA +" TEXT, "
                +KEY_OPTB +" TEXT, "+KEY_OPTC+" TEXT, "+KEY_OPTD+" TEXT);";
        db.execSQL(sql);        
        addQuestions();
//      db.close();
    }
    private void addQuestions()
    {
        Question q1=new Question("We need to cut a cake in more than 6 pieces. How many cuts we must make atleast to get this?","2", "3", "4","5", "3");
        this.addQuestion(q1);
        Question q2=new Question("(896)²-(205)² is divisible by 691", "691", "1101", "Both a and b","None","Both a and b");
        this.addQuestion(q2);
        Question q3=new Question("Reindeer: Fawn:: Llama:?","Colt", "Foal","Cria"," Anubhav", "Cria" );
        this.addQuestion(q3);
        Question q4=new Question("How many meters will I be away from my home if I travel 5 metres towards north, take a right and travel 4 metres and travel 5 metres towards south?", "5", "4", "10","15","4");
        this.addQuestion(q4);
        Question q5=new Question("Cake: Bakery:: Beer: X","Distillery","Wine shop","Brewery","XYZ","Brewery");
        this.addQuestion(q5);
    }
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldV, int newV) {
        // Drop older table if existed
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_QUEST);
        // Create tables again
        onCreate(db);
    }
    // Adding new question
    public void addQuestion(Question quest) {
        //SQLiteDatabase db = this.getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put(KEY_QUES, quest.getQUESTION()); 
        values.put(KEY_ANSWER, quest.getANSWER());
        values.put(KEY_OPTA, quest.getOPTA());
        values.put(KEY_OPTB, quest.getOPTB());
        values.put(KEY_OPTC, quest.getOPTC());
        values.put(KEY_OPTD, quest.getOPTD());
        // Inserting Row
        dbase.insert(TABLE_QUEST, null, values);        
    }
    public List<Question> getAllQuestions() {
        List<Question> quesList = new ArrayList<Question>();
        // Select All Query
        String selectQuery = "SELECT  * FROM " + TABLE_QUEST;
        dbase=this.getReadableDatabase();
        Cursor cursor = dbase.rawQuery(selectQuery, null);
        // looping through all rows and adding to list
        if (cursor.moveToFirst()) {
            do {
                Question quest = new Question();
                quest.setID(cursor.getInt(0));
                quest.setQUESTION(cursor.getString(1));
                quest.setANSWER(cursor.getString(2));
                quest.setOPTA(cursor.getString(3));
                quest.setOPTB(cursor.getString(4));
                quest.setOPTC(cursor.getString(5));
                quest.setOPTD(cursor.getString(6));
                quesList.add(quest);
            } while (cursor.moveToNext());
        }
        // return quest list
        return quesList;
    }
    public int rowcount()
    {
        int row=0;
        String selectQuery = "SELECT  * FROM " + TABLE_QUEST;
        SQLiteDatabase db = this.getWritableDatabase();
        Cursor cursor = db.rawQuery(selectQuery, null);
        row=cursor.getCount();
        return row;
    }

}

---

我试过几种方法。请帮助：（

无论如何，您的按钮变量为null，因此您正在对null调用函数。这就是为什么它会给您带来错误。请尝试查看日志并检查代码以查找错误。

您试图在onclick listener中的按钮视图上使用

findViewbyId（）

，这是错误的

 RadioGroup grp=(RadioGroup)v.findViewById(R.id.radioGroup1);
 RadioButton answer=(RadioButton)v.findViewById(grp.getCheckedRadioButtonId());

在这个

v

被引用到

按钮

，从那里你找不到

RadioGroup

和

RadioButton

，只需将它们初始化为

onCreateView

方法即可

RadioGroup grp;
RadioButton answer

 @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        IqDbHelper db = new IqDbHelper(getActivity());
        View v=inflater.inflate(R.layout.iqquiz, container, false);
        quesList=db.getAllQuestions();
        currentQ=quesList.get(qid);
        txtQuestion=(TextView)v.findViewById(R.id.textView1);
        rda=(RadioButton)v.findViewById(R.id.radio0);
        rdb=(RadioButton)v.findViewById(R.id.radio1);
        rdc=(RadioButton)v.findViewById(R.id.radio2);
        rdd=(RadioButton)v.findViewById(R.id.radio3);
        butNext=(Button)v.findViewById(R.id.button1);
        setQuestionView();
        grp=(RadioGroup)v.findViewById(R.id.radioGroup1);
        answer=(RadioButton)v.findViewById(grp.getCheckedRadioButtonId());
        butNext.setOnClickListener(this);

        return v;

}

并从下方移除

@Override
    public void onClick(View v) {
        if(v==butNext){

        Log.d("yourans", currentQ.getANSWER()+" "+answer.getText());
        if(currentQ.getANSWER().equals(answer.getText()))
        {
            score++;
            Log.d("score", "Your score"+score);
        }
        if(qid<5){                  
            currentQ=quesList.get(qid);
            setQuestionView();
        }else{
            Intent intent = new Intent(getActivity(), ResultActivity.class);
            Bundle b = new Bundle();
            b.putInt("score", score); //Your score
            intent.putExtras(b); //Put your score to your next Intent
            startActivity(intent);
//          finish();
        }
    }
    }

@覆盖
公共void onClick（视图v）{
if（v==butNext）{
Log.d（“yourans”，currentQ.getANSWER（）+“”+answer.getText（））；
if（currentQ.getANSWER（）.equals（answer.getText（）））
{
分数++；
Log.d（“分数”、“你的分数”+分数）；
}
如果（qidDude）你说你有一个空异常，而你没有复制跟踪日志，我们怎么能提供帮助呢？我们是程序员，不是通灵者
RadioGroup grp;
RadioButton answer

 @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        IqDbHelper db = new IqDbHelper(getActivity());
        View v=inflater.inflate(R.layout.iqquiz, container, false);
        quesList=db.getAllQuestions();
        currentQ=quesList.get(qid);
        txtQuestion=(TextView)v.findViewById(R.id.textView1);
        rda=(RadioButton)v.findViewById(R.id.radio0);
        rdb=(RadioButton)v.findViewById(R.id.radio1);
        rdc=(RadioButton)v.findViewById(R.id.radio2);
        rdd=(RadioButton)v.findViewById(R.id.radio3);
        butNext=(Button)v.findViewById(R.id.button1);
        setQuestionView();
        grp=(RadioGroup)v.findViewById(R.id.radioGroup1);
        answer=(RadioButton)v.findViewById(grp.getCheckedRadioButtonId());
        butNext.setOnClickListener(this);

        return v;

}

@Override
    public void onClick(View v) {
        if(v==butNext){

        Log.d("yourans", currentQ.getANSWER()+" "+answer.getText());
        if(currentQ.getANSWER().equals(answer.getText()))
        {
            score++;
            Log.d("score", "Your score"+score);
        }
        if(qid<5){                  
            currentQ=quesList.get(qid);
            setQuestionView();
        }else{
            Intent intent = new Intent(getActivity(), ResultActivity.class);
            Bundle b = new Bundle();
            b.putInt("score", score); //Your score
            intent.putExtras(b); //Put your score to your next Intent
            startActivity(intent);
//          finish();
        }
    }
    }