java - 如何在 ArrayAdapter 中使用带有 4 个不同单选按钮的 Radiogroup

Question

我有一个自定义列表适配器，它在 TextView 中有一个问题，在单选按钮中有四个选项作为答案。所有单选按钮都绑定(bind)在一个单选组中。 问题是我无法跟踪已检查的按钮。滚动按钮时会随机检查。 如何存储针对特定情况检查的单选按钮

<小时/>

公共(public)类 MCQAdapter 扩展了 ArrayAdapter {

public MCQAdapter(Activity context, ArrayList<MCQ> mcq) {
    super(context, 0, mcq);
}

@NonNull
@Override
public View getView(int position, View convertView, ViewGroup parent) {
    View listItemView = convertView;

    if (listItemView == null) {
        listItemView = LayoutInflater.from(getContext()).inflate(R.layout.activity_mcqlist, parent, false);
    }


    final MCQ currentContent = (MCQ) getItem(position);
    TextView content = (TextView) listItemView.findViewById(R.id.Question_Block);
    content.setText(currentContent.getQuestion());

    RadioGroup rg = (RadioGroup) listItemView.findViewById(R.id.Radio_Group);

    final RadioButton rb1 = (RadioButton) listItemView.findViewById(R.id.Option1_Block);
    rb1.setText(currentContent.getOptionA());

    final RadioButton rb2 = (RadioButton) listItemView.findViewById(R.id.Option2_Block);
    rb2.setText(currentContent.getOptionB());

    final RadioButton rb3 = (RadioButton) listItemView.findViewById(R.id.Option3_Block);
    rb3.setText(currentContent.getOptionC());

    final RadioButton rb4 = (RadioButton) listItemView.findViewById(R.id.Option4_Block);
    rb4.setText(currentContent.getOptionD());

    return listItemView;

}

}

public class MCQ {

String question,optionA,optionB,optionC,optionD,answer,userAnswer;

public MCQ(String quest,String a,String b,String c, String d,String ans){

    question = quest;
    optionA = a;
    optionB = b;
    optionC = c;
    optionD = d;
    answer = ans;

}

public String getQuestion(){
    return question;
}

public String getOptionA() {
    return optionA;
}

public String getOptionB() {
    return optionB;
}

public String getOptionC() {
    return optionC;
}

public String getOptionD() {
    return optionD;
}

public String getAnswer() {
    return answer;
}

public String getUserAnswer() {
    return userAnswer;
}

public void setUserAnswer(String userAnswer) {
    this.userAnswer = userAnswer;
}

}

public class PropertiesOfConstructionMaterail extends AppCompatActivity {

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

    final ArrayList<MCQ> mcq = new ArrayList<MCQ>();

    //Creating Different Instance Of MCQ to genarte various questions for Properties of Consrtuction Material
    mcq.add(new MCQ("The property of material by which it can be beaten or rolled into thin plates, is called ?",
            "Malleability","Ductility","Plasticity","Elasticity","Malleability"));
    mcq.add(new MCQ("The property by which a body returns to its original shape after removal of the force, is called ?",
            "Plasticity","Elasticity","Ductility","Malleability","Elasticity"));
    mcq.add(new MCQ("The property of a material by which it can be drawn into smaller section due to tension, is called ?"
            ,"Plasticity","Ductility","Elasticity","Malleability","Ductility")); 

MCQAdapter adapter = new MCQAdapter(this,mcq);

    ListView listView = (ListView) findViewById(R.id.list);
    listView.setAdapter(adapter);
}

}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/activity_mcqlist"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.silen.civilengineeringmcq.MCQList"
android:orientation="vertical">

<TextView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:id="@+id/Question_Block"
    android:textSize="18dp"
    android:textStyle="bold"/>

<RadioGroup
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:id="@+id/Radio_Group">

    <RadioButton
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/Option1_Block"
        android:checked="false"/>

    <RadioButton
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/Option2_Block"
        android:checked="false"/>

    <RadioButton
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/Option3_Block"
        android:checked="false"/>

    <RadioButton
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/Option4_Block"
        android:checked="false"/>

</RadioGroup>

Answer 1

您应该围绕 PoJo 类 (MCQ) 创建一个包装器，将其命名为 ViewModel，它将 View 的当前状态存储在适配器内。在您的情况下，该状态是单选按钮的状态。

它看起来像:

class ViewModel extends MCQ {
    MCQ mcq;

    int radioButtonSelectedId;

    public ViewModel(MCQ mcq) {
        this.mcq = mcq;
        this.radioButtonSelectedId = R.id.Option1_Block;
    }

    public void setRadioButtonSelectedId(int id) {
        this.id = id;
    }

    public int getRadioButtonSelectedId() {
        return id;
    }

    //delegates to mcq getter/setter methods
}

您的getView方法:

public View getView(int position, View convertView, ViewGroup parent) {
//your logic above
    radioGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(RadioGroup group, int checkedId) {
                viewModel.setRadioButtonSelectedId(checkedId);
            }
        });

    //same for other radio buttons
    rb1.setChecked(viewModel.getRadioButtonSelectedId() == R.id.Option1_Block);
//your logic below
}

因此，正如我上面提到的，适配器内的数组列表将包含 ViewModel 包装器，而不是直接包含 MCQ 类

final ArrayList<ViewModel> mcqList = new ArrayList<>();
MCQ mcq = new MCQ("The property of material by which it can be beaten or rolled into thin plates, is called ?",
        "Malleability","Ductility","Plasticity","Elasticity","Malleability")
mcqList.add(new ViewModel(mcq));

我认为你应该有一个选择