Question

当我点击保存按钮时，我当前正试图将我的微调器的选定位置保存在文本文件中。

目前这就是我所拥有的。微调器工作正常但是当我尝试添加零件以保存微调器位置（saveSettings）时，这就是我的问题所在。

我收到以下错误：

Error:(56, 85) error: incompatible types: String cannot be converted to File

Error:(61, 40) error: method getPosition in class ArrayAdapter<T> cannot be applied to given types;
required: CharSequence
found: no arguments
reason: actual and formal argument lists differ in length
where T is a type-variable:
T extends Object declared in class ArrayAdapter

Error:Execution failed for task ':app:compileDebugJavaWithJavac'.
> Compilation failed; see the compiler error output for details.

我认为问题在于我尝试将两种不同的方法结合起来，但是我还在学习，我对于保存选定的微调器位置的正确方法感到困惑。

public class MainActivity extends AppCompatActivity {
    Spinner spinner;
    ArrayAdapter<CharSequence> adapter;
    String SelectedServer;

    /**
    * ATTENTION: This was auto-generated to implement the App Indexing API.
    * See https://g.co/AppIndexing/AndroidStudio for more information.
    */
    private GoogleApiClient client;

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

        spinner = (Spinner) findViewById(R.id.spinner);
        adapter = ArrayAdapter.createFromResource(this, R.array.serverUrl, android.R.layout.simple_spinner_item);
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        spinner.setAdapter(adapter);
        spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {

                SelectedServer = parent.getItemAtPosition(position).toString();

            }

            @Override
            public void onNothingSelected(AdapterView<?> parent) {

            }


        });
    }

    public void saveSettings(View view) {

        File txtFolder = new File(Environment.getExternalStorageDirectory().getAbsolutePath()+"/MyFolder/");
        if (!txtFolder.exists()) {
            txtFolder.mkdir();
        }
        File file = new File(txtFolder, "setting.txt");
        String.valueOf(SelectedServer.getBytes());
        try {
            FileOutputStream fos = new FileOutputStream(file);
            fos.write(SelectedServer.getBytes());
            fos.close();
            Toast.makeText(getApplicationContext(),"Setting Saved", Toast.LENGTH_LONG).show();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

    }
}

所以我正在寻找帮助来解决这个问题。有什么建议吗？

Answer 1

这一行是第一个错误：

File txtFolder = Environment.getExternalStorageDirectory().getAbsolutePath()+"/MyFolder/";

您正在为文件分配string值。您可能希望将该值放在构造函数new File(String path)中：

File txtFolder = new File(Environment.getExternalStorageDirectory().getAbsolutePath()+"/MyFolder/");

第二个错误是：

String SelectedServer = adapter.getPosition().toString();

我会使用String.valueOf(adapter.getPosition());或隐式转化""+adapter.getPosition();。

如果情况并非如此，那么您需要检查getPosition返回的内容（可能是空的）。

将微调器位置保存到文本文件

1 个答案: