Question

您好我正在创建一个测验应用程序。我想在我的提交按钮中添加一个功能，如果用户没有在radiobutton中选择任何答案，将会有一条消息说“请选择答案”这是代码

  public void onClickNext(View view) {
    String level = getIntent().getExtras().getString("level");
    DbHelper db = new DbHelper(this);
    db.getQuestByLevel(level, qnum);

    RadioGroup grp = (RadioGroup) findViewById(R.id.questionAndAnswers);
    RadioButton answer = (RadioButton) findViewById(grp.getCheckedRadioButtonId());
    if (corAnswer != null && corAnswer.equalsIgnoreCase((String) answer.getText())) {
        score++;
        Log.d("answer", "Your score" + score);
    }
    if (qnum <= 5) {

    }
    else {
        Intent intent = new Intent(QuizActivity.this, ResultActivity.class);
        Bundle b = new Bundle();
        b.putInt("score", score);
        intent.putExtras(b);
        startActivity(intent);
        finish();
    }

    txtQuestion.setText(db.question);
    rda.setText(db.optionA);
    rdb.setText(db.optionB);
    rdc.setText(db.optionC);
    rdd.setText(db.optionD);
    corAnswer = db.answer;
    qnum++;
    rdgrp.clearCheck();
}

}

Answer 1

在以下一行

RadioButton answer = (RadioButton) findViewById(grp.getCheckedRadioButtonId());

如果未选中RadioButton，getCheckedRadioButtonId()将返回＆＃34; -1＆＃34;并且由于没有带有该ID的视图，＆＃34;回答＆＃34;将是null。

所以你可以做以下

if (answer == null)
{
    Toast.makeText(MyActivity.this, "select an answer please", Toast.LENGTH_SHORT).show();

    // nothing more to do here so 
    return;
}
if (corAnswer!= null && corAnswer.equalsIgnoreCase((String) answer.getText())
{
    // continue as before
}

Android测验消息提醒

1 个答案: