java - 用户填充的 ListView 中的 TextView 值的总和

Question

我是编程新手，需要您的帮助。我有一个 ListView ，其中包含三个由用户填充的 TextView ，其中一个是数字。我想要的是在另一个 TextView 中的 ListView 下显示所有这些 TextView 的总值。每次用户添加或删除项目时都应该更新它。我找到了一些关于如何求和的代码，但我不确定将它放在哪里以及何时调用该方法，因为用户填充了 lv 并且它在开始时是空的。更新总和这件事对我来说更难了。

这是适配器:

Public class MyAdapter extends BaseAdapter {

private ArrayList<MyItem> mItem;

public MyAdapter(ArrayList<MyItem> items)
{
    this.mItem = items;
}



@Override
public int getCount() {
    return this.mItem.size();
}

@Override
public Object getItem(int position) {
    return mItem.get(position);
}

@Override
public long getItemId(int position) {
    return position;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    ViewHolder myVH;
    if (convertView == null) {
        LayoutInflater inflater = LayoutInflater.from(parent.getContext());
        convertView = inflater.inflate(R.layout.items_lv, parent, false);
        myVH = new ViewHolder(convertView);
        convertView.setTag(myVH);
    } else {
        myVH = (ViewHolder) convertView.getTag();
    }

    MyItem item = this.mItem.get(position);
    myVH.tvSurname.setText(item.getgSurname());
    myVH.tvName.setText(item.getgName());
    myVH.tvNumber.setText(item.getgNumber());
    return convertView;
}

public void addnewItem (MyItem item) {
    this.mItem.add(item);
    this.notifyDataSetChanged();
}

public void deleteAt(int position) {
    this.mItem.remove(position);
    this.notifyDataSetChanged();
}


private class ViewHolder {

    public TextView tvSurname, tvName, tvNumber;

    public ViewHolder(View itemView) {
        tvSurname = (TextView) itemView.findViewById(R.id.tvaSurname);
        tvName = (TextView) itemView.findViewById(R.id.tvaName);
        tvNumber = (TextView) itemView.findViewById(R.id.tvaNumberitems);
    }

}

这是我想在 ListView 下显示总和的 MainActivity

public class MainActivity extends AppCompatActivity implements View.OnClickListener {


public static final  String OUTPUT_SURNAME = "surname";
public static final  String OUTPUT_NAME = "name";
public static final  String OUTPUT_NUMBER = "number";
public static final int REQUEST_CODE = 1;

ListView lvPeople;
MyAdapter myAdapter;
Button bAdd;
TextView tvSum, tvResult;

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

private void SetUpUI() {
    lvPeople = (ListView) findViewById(R.id.lvPeople);
    bAdd = (Button) findViewById(R.id.bAdd);
    tvSum = (TextView) findViewById(R.id.tvSum);
    tvResult = (TextView) findViewById(R.id.tvResult);
    bAdd.setOnClickListener(this);



        ArrayList<MyItem> items = Database.getInstance(this).getAllItems();
        myAdapter = new MyAdapter(items);
        lvPeople.setAdapter(myAdapter);


    lvPeople.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
        @Override
        public boolean onItemLongClick(AdapterView<?> parent, View view, final int position, long id) {
            AlertDialog.Builder dialogBuilder = new AlertDialog.Builder(MainActivity.this);
            dialogBuilder.setMessage("Do you want to delete person?");
            dialogBuilder.setCancelable(true);
            dialogBuilder.setPositiveButton(
                    "Yes",
                    new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int id) {
                            Database.getInstance(getApplicationContext()).deletePerson((MyItem) myAdapter.getItem(position));
                            myAdapter.deleteAt(position);
                            dialog.cancel();
                        }
                    });

            dialogBuilder.setNegativeButton(
                    "No",
                    new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int id) {
                            dialog.cancel();
                        }
                    });

            AlertDialog alertDialog = dialogBuilder.create();
            alertDialog.show();
            return true;
        }
    });
}


@Override
public void onClick(View v) {
    Intent intent = new Intent(this, AddPerson.class);
    startActivityForResult(intent, REQUEST_CODE);
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    if (requestCode == REQUEST_CODE && resultCode == RESULT_OK) {

        String surname = data.getStringExtra(OUTPUT_SURNAME);
        String name = data.getStringExtra(OUTPUT_NAME);
        String number = data.getStringExtra(OUTPUT_NUMBER);
        MyItem item = new MyItem(surname, name, number);
        Database.getInstance(getApplicationContext()).addPerson(item);
        myAdapter.addnewItem(new MyItem(surname, name, number));

    }
}

Here是它看起来应该如何的想法

Answer 1

尝试这样的事情:

public void onButtonClick(View view){
   int sum = 0;
   for(i=0;i<= listView.getCount; i++){
   TextView textViewNumber = (TextView)view.findViewById(R.id.idOfUrTextViewOnWhichUrAreDisplayingNumericalValue);
   int value = Integer.parseInt(textViewNumber.getText().toString());
   sum = sum + value;
   }
   return sum; 
}