Question

我正在开发一个简单的MCQ测验，下面的代码应该显示用户响应是正确还是错误，如果用户选择了错误的答案，则突出显示正确的答案。对于第一个问题它完全正常，如果我按下接下来继续下一个问题我得到这个

03-08 18:47:12.701 3230-3230 /？ E / AndroidRuntime：致命异常：主要处理：com.example.useradmin.dbquiz，PID：3230 显示java.lang.NullPointerException at com.example.useradmin.dbquiz.MainActivity $ 1.onCheckedChanged（MainActivity.java:109）在android.widget.RadioGroup.setCheckedId（RadioGroup.java:174）在android.widget.RadioGroup.access $ 600（RadioGroup.java:54）在android.widget.RadioGroup $ CheckedStateTracker.onCheckedChanged（RadioGroup.java:358）在android.widget.CompoundButton.setChecked（CompoundButton.java:130）在android.widget.RadioGroup.setCheckedStateForView（RadioGroup.java:181）在android.widget.RadioGroup.check（RadioGroup.java:161）在android.widget.RadioGroup.clearCheck（RadioGroup.java:209）在com.example.useradmin.dbquiz.MainActivity $ 2.onClick（MainActivity.java:125）在android.view.View.performClick（View.java:4438）在android.view.View $ PerformClick.run（View.java:18422）在android.os.Handler.handleCallback（Handler.java:733）在android.os.Handler.dispatchMessage（Handler.java:95）在android.os.Looper.loop（Looper.java:136）在android.app.ActivityThread.main（ActivityThread.java:5001） at java.lang.reflect.Method.invokeNative（Native Method）在java.lang.reflect.Method.invoke（Method.java:515）在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:785）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:601）在dalvik.system.NativeStart.main（本地方法）

这是我的代码：

txtQuestion = (TextView) findViewById(R.id.txtQuestion);
    rda = (RadioButton) findViewById(R.id.rdb1);
    rdb = (RadioButton) findViewById(R.id.rdb2);
    rdc = (RadioButton) findViewById(R.id.rdb3);
    rdd = (RadioButton) findViewById(R.id.rdb4);
    butNext = (Button) findViewById(R.id.btnNext);
    rbgroup = (RadioGroup) findViewById(R.id.rbGroup);
    mquestionsList = myDbHelper.getListQuestions();
    moptionsList = myDbHelper.getListOptions();
    currentQ = mquestionsList.get(question_id);
    currentOptions = moptionsList.get(option_id);

    setQuestion();


    rbgroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
        @Override
        public void onCheckedChanged(RadioGroup group, int checkedId) {

            if (group.getCheckedRadioButtonId() != -1)
            {

               RadioButton user_response = null;
                int i = 0;


                while (user_response == null && i < group.getChildCount()) {
                    RadioButton temp = (RadioButton) group.getChildAt(i);
                    String answer = temp.getText().toString();

                    if (currentQ.getCorrect_Ans().equalsIgnoreCase(answer)) {
                        user_response = temp;
                    }

                    i++;
                }

                int checked = group.getCheckedRadioButtonId();
                RadioButton checkedBtn = (RadioButton) findViewById(checked);

                if (user_response == checkedBtn) {
                    score++;
                } else {
                    checkedBtn.setTextColor(Color.RED);
                }

                user_response.setTextColor(Color.GREEN);
                Toast.makeText(getApplicationContext(),""+score,Toast.LENGTH_SHORT).show();


            }
        }

    });

    butNext.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {


            if (question_id < mquestionsList.size()) {
                currentQ = mquestionsList.get(question_id);
                currentOptions = moptionsList.get(option_id);
                rbgroup.clearCheck();
                //rbgroup.setEnabled(false);
                setQuestion();
            }


        }
    });

}
private void setQuestion() {

    txtQuestion.setText(currentQ.getQuestion_id() + ". " + currentQ.getQuestion());

    rda.setText(currentOptions.getOpt1());
    rdb.setText(currentOptions.getOpt2());
    rdc.setText(currentOptions.getOpt3());
    rdd.setText(currentOptions.getOpt4());

    question_id++;
    option_id++;
}

错误在这一行： user_response.setTextColor（Color.GREEN）;

单选按钮java.lang.NullPointerException

0 个答案: