如何从列表视图中获取单选组的值？

Question

我正在开发Android考勤应用程序，老师可以在其中参加考勤。Here is the image。我以here 为例。但我没有得到，当单击提交按钮时如何获取单选按钮的值。

出勤率.class

public class Attendance extends Activity {

    private ListView listView1;
    Button submit;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.attendance);
        submit = (Button) findViewById(R.id.testbutton);

        Option weather_data[] = new Option[]
                {
                        new Option("Student1"),
                        new Option("Student2"),
                        new Option("Student3"),
                        new Option("Student4"),
                        new Option("Student5"),
                        new Option("Student6")

                };
        RadioGroupAdapter adapter = new RadioGroupAdapter(this,
                R.layout.listitem, weather_data);
        listView1 = (ListView)findViewById(R.id.list);
        listView1.setAdapter(adapter);
    }



}

RadioGroupAdapter.class

public class RadioGroupAdapter extends ArrayAdapter<Option> {

    Context context;
    int layoutResourceId;
    Option data[] = null;

    public RadioGroupAdapter(Context context, int layoutResourceId,
                             Option[] data) {
        super(context, layoutResourceId, data);
        this.layoutResourceId = layoutResourceId;
        this.context = context;
        this.data = data;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View row = convertView;
        MatrixHolder holder = null;

        if (row == null) {
            LayoutInflater inflater = ((Activity) context).getLayoutInflater();
            row = inflater.inflate(layoutResourceId, parent, false);

            holder = new MatrixHolder();
            holder.txtTitle = (TextView) row.findViewById(R.id.heading);
            holder.group = (RadioGroup) row.findViewById(R.id.radio_group1);
            final RadioButton[] rb = new RadioButton[2];
            for(int i=0; i<2; i++){
                rb[i]  = new RadioButton(context);
                //rb[i].setButtonDrawable(R.drawable.single_radio_chice);
                rb[i].setId(i);
                RadioGroup.LayoutParams params = new RadioGroup.LayoutParams(
                        0, LayoutParams.WRAP_CONTENT);
                params.weight=1.0f;
                params.setMargins(5, 0, 5, 10);
                holder.group.addView(rb[i],params); //the RadioButtons are added to the radioGroup instead of the layout
            }
            row.setTag(holder);
        } else {
            holder = (MatrixHolder) row.getTag();
        }

        Option option = data[position];
        holder.txtTitle.setText(option.title);
        return row;
    }

    static class MatrixHolder {
        TextView txtTitle;
        RadioGroup group;
        int position;
    }
}

option.class

public class Option {
    public String title;
    int selectedId=-1;
    public Option(){
        super();
    }

    public Option( String title) {
        super();
        this.title = title;

    }

}

Logcat

05-17 13:17:13.254 5141-5141/? E/AndroidRuntime: FATAL EXCEPTION: main
                                                 Process: org.pitechnologies.teacher, PID: 5141
                                                 java.lang.IllegalStateException: Could not execute method of the activity
                                                     at android.view.View$1.onClick(View.java:4020)
                                                     at android.view.View.performClick(View.java:4780)
                                                     at android.view.View$PerformClick.run(View.java:19866)
                                                     at android.os.Handler.handleCallback(Handler.java:739)
                                                     at android.os.Handler.dispatchMessage(Handler.java:95)
                                                     at android.os.Looper.loop(Looper.java:135)
                                                     at android.app.ActivityThread.main(ActivityThread.java:5257)
                                                     at java.lang.reflect.Method.invoke(Native Method)
                                                     at java.lang.reflect.Method.invoke(Method.java:372)
                                                     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
                                                     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
                                                  Caused by: java.lang.reflect.InvocationTargetException
                                                     at java.lang.reflect.Method.invoke(Native Method)
                                                     at java.lang.reflect.Method.invoke(Method.java:372)
                                                     at android.view.View$1.onClick(View.java:4015)
                                                     at android.view.View.performClick(View.java:4780) 
                                                     at android.view.View$PerformClick.run(View.java:19866) 
                                                     at android.os.Handler.handleCallback(Handler.java:739) 
                                                     at android.os.Handler.dispatchMessage(Handler.java:95) 
                                                     at android.os.Looper.loop(Looper.java:135) 
                                                     at android.app.ActivityThread.main(ActivityThread.java:5257) 
                                                     at java.lang.reflect.Method.invoke(Native Method) 
                                                     at java.lang.reflect.Method.invoke(Method.java:372) 
                                                     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903) 
                                                     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698) 
                                                  Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'org.pitechnologies.teacher.Option[] org.pitechnologies.teacher.RadioGroupAdapter.getItems()' on a null object reference
                                                     at org.pitechnologies.teacher.Attendance.onClick(Attendance.java:40)
                                                     at java.lang.reflect.Method.invoke(Native Method) 
                                                     at java.lang.reflect.Method.invoke(Method.java:372) 
                                                     at android.view.View$1.onClick(View.java:4015) 
                                                     at android.view.View.performClick(View.java:4780) 
                                                     at android.view.View$PerformClick.run(View.java:19866) 
                                                     at android.os.Handler.handleCallback(Handler.java:739) 
                                                     at android.os.Handler.dispatchMessage(Handler.java:95) 
                                                     at android.os.Looper.loop(Looper.java:135) 
                                                     at android.app.ActivityThread.main(ActivityThread.java:5257) 
                                                     at java.lang.reflect.Method.invoke(Native Method) 
                                                     at java.lang.reflect.Method.invoke(Method.java:372) 
                                                     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903) 
                                                     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698) 

Answer 1

由于 ListView 重复使用视图，因此您需要保持每个视图相对于该视图（行）的位置。

RadioGroupAdapter.java

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    View row = convertView;
    MatrixHolder holder = null;

    if (row == null) {
        LayoutInflater inflater = ((Activity) context).getLayoutInflater();
        row = inflater.inflate(layoutResourceId, parent, false);

        holder = new MatrixHolder();
        holder.txtTitle = (TextView) row.findViewById(R.id.heading);

        holder.group = (RadioGroup) row.findViewById(R.id.radio_group);

        holder.group.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(RadioGroup radioGroup, int i) {
                int pos = (int) radioGroup.getTag();
                data[pos].selectedId = radioGroup.getCheckedRadioButtonId();
            }
        });
        row.setTag(holder);
    } else {
        holder = (MatrixHolder) row.getTag();
    }

    Option option = data[position];
    holder.txtTitle.setText(option.title);
    holder.group.setTag(position);
    if (option.selectedId != -1) {//check at-least one is selected
        holder.group.check(option.selectedId);
    }
    return row;
}

//get all items attached to adapter
public Option[] getItems() {
    return data;
}

Attendance.java

public void onClick(View view) {
    if (view.getId() == R.id.submit) {
        Option[] items = adapter.getItems();
        for (Option opt : items) {
            if (opt.selectedId != -1) {
                Log.i("TAG", "Title " + opt.title + " Selected " + (opt.selectedId == R.id.radio_a ? "A" : "P"));
            } else {
                Log.i("TAG", "Title " + opt.title + " Not Selected Any Button");
            }
        }
    }
}

Option.java

public class Option {
    String title;
    int selectedId=-1;
    //your constructor
}

Answer 2

你需要这样实现单选按钮上的监听器

RadioGroup radioGroup = (RadioGroup) findViewById(R.id.yourRadioGroup);        
radioGroup.setOnCheckedChangeListener(new OnCheckedChangeListener(){
    @Override
    public void onCheckedChanged(RadioGroup group, int checkedId) {
       // checkedId is the RadioButton selected
    }
});

然后将选中按钮的状态保存在您喜欢的数据结构中。 之后，当您按下按钮提交时，您可以读取您的数据结构并发送您选中/未选中的数据。

我希望这会有所帮助！

Answer 3

尝试在自定义 Arrayadapter 中这样实现 radio[i].setOnCheckedChangeListener(...) 和内部监听器将 value(boolean) 存储在某个变量中，并包含 getter 函数来检索它。