当我从另一个活动获得结果时，ListView仅更新一个视图项，如何获得所有过去的结果？

Question

当我从另一个活动中获取结果时，ListView仅更新一个视图项，如何获取用户输入的所有过去结果并将其显示在ListView中？

我正在使用意图在两个活动之间发送数据。

这个想法是用户列出他/她曾经访问过的所有国家。 显示内容可能如下所示：

1964年瑞典

1970年芬兰

1979丹麦

1980英格兰

1982挪威

...

2009乌克兰

用户通过按菜单→添加国家来添加新国家。 此操作将显示一个新页面（活动），用户可以在其中添加新条目（国家/地区）。

我已经被困了8个小时，所以任何帮助都将派上用场。 谢谢！

MyCountries.java

import android.app.Activity;
import android.content.ClipData;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;
import java.util.*;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeoutException;

/**
 * Created by root on 2016-09-03.
 */
public class MyCountries extends Activity {

    private ListView listView;
    private MyAdapter adapter;
    private Activity main_activity;
    String year="";
    String country="";
    ArrayList<String> info = new ArrayList<>();

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.action_bar);

        listView = (ListView)findViewById(R.id.listView);
        adapter = new MyAdapter(this,R.layout.list_item, info);

        main_activity = this;  // Simplifies Intent handling
    }

    @Override
    protected void onStop() {
        super.onStop();

        //listView.setAdapter(adapter);
    }

    @Override
    protected void onStart() {
        super.onStart();

    }

    @Override
    protected void onRestart() {
        super.onRestart();  // Always call the superclass method first

        // Activity being restarted from stopped state
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // An XML based menu specification.
        // See res/menu/action_menu.xml for details
        getMenuInflater().inflate(R.menu.action_menu, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.add_integer_menu:

                /* Start new Activity that returns a result */
                Intent intent = new Intent(main_activity,Read_Country.class);
                main_activity.startActivityForResult(intent,0);

                return true;

            case android.R.id.home:  // Predefined icon ID

                // app icon in action bar clicked ==>  go home
                Intent intent2 = new Intent(this, MainList.class);
                intent2.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
                startActivity(intent2);
                return true;
            default:
                return super.onOptionsItemSelected(item);
        }
    }

        /*
         * Adapter to populate list with colors and integers
         */
    class MyAdapter extends ArrayAdapter<Object> {

        public MyAdapter(Context context, int textViewResourceId, List list) {
            super(context,textViewResourceId, list);
        }

        @Override   // Called when updating the ListView
        public View getView(int position, View convertView, ViewGroup parent) {
            /* Reuse super handling ==> A TextView from R.layout.list_item */
            TextView tv = (TextView) super.getView(position,convertView,parent);

                /* Find corresponding entry */
                Object obj = getItem(position);

            /* Update TextView with string information */
                tv.setText(obj.toString());
                tv.setBackgroundColor(0xffffffff);
                tv.setTextColor(0xff000000);  // Black

            return tv;
        }
    }

    /** Called when the activity receives a results. */
    @Override
    protected void onActivityResult(int requestCode,int resultCode, Intent result) {
        if (resultCode == RESULT_OK) {
            country = result.getStringExtra("result1");
            year = result.getStringExtra("result2");
          //this is where I update the arrayList, which is an element of the arrayadapter
            info.add(year + " " + country);

/*            for (int i = 0; i < info.size(); i++) {
                System.out.println(info.get(i));
            }
            //adapter.notifyDataSetChanged();
          adapter.add(year + " " + country);  // Add new string to data list
           */
            listView.setAdapter(adapter);
        }
    }
}

Reader_Country.java

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;

/**
 * Created by root on 2016-09-03.
 */
public class Read_Country extends Activity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.read_country);

        /* Assign listener to button */
        Button button = (Button)findViewById(R.id.done_button);
        button.setOnClickListener(new ButtonClick());
    }

    private class ButtonClick implements View.OnClickListener {
        public void onClick(View v) {
            EditText reader = (EditText)findViewById(R.id.country_reader);
            String country = reader.getText().toString();

            EditText reader2 = (EditText)findViewById(R.id.year_reader);
            String year = reader2.getText().toString();

            /* Create new result intent */
            Intent reply = new Intent();
            reply.putExtra("result1", country);
            reply.putExtra("result2", year);
            setResult(RESULT_OK,reply);
            finish();   // Close this activity
        }
    }
}

Answer 1

我认为，针对您的问题的最佳解决方案是使用SQLDatabase在用户电话本身上创建本地数据库。

但是，如果您希望用户无论登录到哪个手机，都可以查看他已在您的应用程序中注册的这些国家，那么我建议您使用一些可能的数据库，我认为FireBase是一个不错的选择。

希望这对您有所帮助:)