android - ListView 不显示文本文件中的文本

Question

我有一个关于 Activity 的 ListView ，我想在其中显示我从文本文件中读取的信息。这是上述 Activity (类)的代码:

public class ViewData extends AppCompatActivity {

    //code to show strings from file
    private ArrayList<String>  readFromFile(Context context) {

        ArrayList<String> receiveString=new ArrayList<String>(  );

        try {
            InputStream inputStream = context.openFileInput(AddDataActivity.FileName);

            if (inputStream != null) {
                InputStreamReader inputStreamReader = new InputStreamReader(inputStream);
                BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
               String tempString="";
                while ((tempString=bufferedReader.readLine()) != null) {

                    receiveString.add(tempString);
                }

                inputStream.close();

            }
        } catch (FileNotFoundException e) {
            Log.e("login activity", "File not found: " + e.toString());
        } catch (IOException e) {
            Log.e("login activity", "Can not read file: " + e.toString());
        }

        return receiveString;
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_view_data);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });

        ListView listView=(ListView)findViewById(R.id.listView);

        // Define a new Adapter
        // First parameter - Context
        // Second parameter - Layout for the row
        // Third parameter - ID of the TextView to which the data is written
        // Forth - the Array of data

        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
                android.R.layout.simple_list_item_1, android.R.id.text1,readFromFile(getApplicationContext()));


        // Assign adapter to ListView
        listView.setAdapter(adapter);

        // ListView Item Click Listener
//        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
//
//            @Override
//            public void onItemClick(AdapterView<?> parent, View view,
//                                    int position, long id) {
//
//                // ListView Clicked item index
//                int itemPosition     = position;
//
//                // ListView Clicked item value
//                String  itemValue    = (String) listView.getItemAtPosition(position);
//
//                // Show Alert
//                Toast.makeText(getApplicationContext(),
//                        "Position :"+itemPosition+"  ListItem : " +itemValue , Toast.LENGTH_LONG)
//                        .show();
//
//            }
//
//        });



    }


}

我有一个应该触发此 Activity (启动它)的菜单按钮，在 onCreate 中，我想从文件中读取并显示我在另一个 Activity 中保存到文件中的文本内容。但是，我目前看到以下结果，无论对提到的文本文件保存什么更改，结果似乎总是一样的:

这是我的布局的内容 View :

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:context="mhd.myupliftingmate.ViewData"
    tools:showIn="@layout/activity_view_data">

    <ListView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/listView"
        android:layout_alignParentTop="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true" />
</RelativeLayout>

这是我的主菜单布局，其中调用了 Activity ViewData:

<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    tools:context="mhd.myupliftingmate.MainActivity">
    <item
        android:id="@+id/action_settings"
        android:orderInCategory="100"
        android:title="@string/action_settings"
        android:icon="@drawable/settings"
        app:showAsAction="ifRoom"
        />
    <item app:showAsAction="ifRoom"
        android:orderInCategory="101"
        android:title="Add Data"
        android:id="@+id/action_addData"
        android:onClick="openAddActivity"
        android:icon="@drawable/input"
/>
    <item
        android:orderInCategory="102"
        android:title="View Data"
        android:id="@+id/action_viewData"
        android:onClick="openViewActivity"
        android:icon="@drawable/text"
        app:showAsAction="ifRoom"
/>


</menu>

我还添加了文件写入代码，以防出现问题。

public class AddDataActivity extends AppCompatActivity {

    public static final String FileName="data.txt";
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_add_data);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });
    }

    public void saveToFile(View view) {
//        private void writeToFile(String data,Context context) {
        Context context=getApplicationContext();
        View userText=(EditText) findViewById(R.id.userText);
        String inputString=userText.toString();
            try {
                OutputStreamWriter outputStreamWriter = new OutputStreamWriter(context.openFileOutput(FileName, Context.MODE_PRIVATE));
                outputStreamWriter.write(inputString);
                outputStreamWriter.close();
            }
            catch (IOException e) {
                Log.e("Exception", "File write failed: " + e.toString());
            }
        }

}

我不知道我是否需要实现我的 ArrayAdapter 版本。我实际上并不完全理解它及其参数是如何工作的。

Answer 1

改变

       String inputString=userText.toString();

到

       String inputString=userText.getText().toString();