Android中的回调

我是Android和整个程序设计的新手，我在回调方面需要一些帮助。我了解回调的要点，但不确定如何实现。

上下文：我正在编写一个简单的笔记应用程序，该应用程序允许用户编写文本并将其保存到该应用程序中。然后，用户可以使用按钮请求读取文件。然后，文本将显示在主活动的textview上。有一个选项可以擦除此文件，这是通过弹出确认窗口完成的，这是另一项活动。该弹出窗口包含2个按钮，一个按钮取消，另一个按钮擦除。如果文件不为空，它将擦除，如果为空，则不执行任何操作。我不确定这是否是实现它的最佳方法，但我想使用“擦除”按钮回调到主活动以清除textview。我想到的方法是使用回调将布尔值发送回。主要活动将检查布尔值是否为true，如果为true则清除textview。

主要活动代码

public class MainActivity extends AppCompatActivity implements Popout.ClearTextView {

    Button bnRead,bnWrite,bnClear;
    TextView tvFileOP;
    EditText etInput;
    //    private static final String INPUT_CONTENT = "inputContent";
    public static final String  TV_CONTENT = "textViewContent";

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

        bnRead = (Button) findViewById(R.id.bnRead);
        bnWrite = (Button) findViewById(R.id.bnWrite);
        bnClear = (Button) findViewById(R.id.bnClear);

        tvFileOP = (TextView) findViewById(R.id.tvFileOP);
        etInput = (EditText) findViewById(R.id.etInput);
        tvFileOP.setMovementMethod(new ScrollingMovementMethod());

        final String fileName = "test_file";
        String data;

        bnRead.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                try {
                    FileInputStream fIn = openFileInput(fileName);
                    int c;
                    String temp = "";
                    while ( (c=fIn.read()) != -1){
                        temp = temp + Character.toString((char) c);
                    }
                    tvFileOP.setText(temp);
                    Toast.makeText(getBaseContext(),"file successfully read", Toast.LENGTH_LONG).show();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });

        bnWrite.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String data = etInput.getText().toString();
                try {
                    FileOutputStream fOut = openFileOutput(fileName,MODE_APPEND);
                    fOut.write(data.getBytes());
                    fOut.close();
                    etInput.setText("");
                    Toast.makeText(getBaseContext(),"file successfully written", Toast.LENGTH_LONG).show();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });

        bnClear.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                startActivity(new Intent(MainActivity.this,Popout.class));
            }
        });

    }

    @Override
    protected void onSaveInstanceState(@NonNull Bundle outState) {
        outState.putString(TV_CONTENT,tvFileOP.getText().toString());
        super.onSaveInstanceState(outState);
    }

    @Override
    protected void onRestoreInstanceState(@NonNull Bundle savedInstanceState) {
        super.onRestoreInstanceState(savedInstanceState);
        tvFileOP.setText(savedInstanceState.getString(TV_CONTENT));
    }


    @Override
    public void clearTextView(Boolean clear) {
        if (clear){
            tvFileOP.setText("");
        }
    }
}

弹出确认菜单代码

public class Popout extends AppCompatActivity {

    Button bnClosepopup,bnWipe;
    TextView tvConfirmation;
    String fileName = "test_file";
    TextView tvFileOP;

    public interface ClearTextView {
        public void clearTextView(Boolean clear);
    }

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

        bnClosepopup = (Button) findViewById(R.id.bnClosepopup);
        bnWipe = (Button) findViewById(R.id.bnWipe);
        tvConfirmation = (TextView) findViewById(R.id.tvConfirmation);


        //HIDING THE TOOL BAR AT THE TOP OF THE SCREEN
        this.getSupportActionBar().hide();

        //GETTING THE SIZE OF THE SCREEN
        DisplayMetrics displayMetrics = new DisplayMetrics();
        getWindowManager().getDefaultDisplay().getMetrics(displayMetrics);
        int height = displayMetrics.heightPixels;
        int width = displayMetrics.widthPixels;
        getWindow().setLayout((int) (width*0.8) , (int) (0.8*height));

        bnClosepopup.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                finish();
            }
        });

        bnWipe.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                try {
                    File dir = getFilesDir();
                    File file = new File(dir, fileName);
                    boolean deleted = file.delete();
                    Toast.makeText(getBaseContext(),"file has been deleted",Toast.LENGTH_SHORT).show();

                } catch (Exception e) {
                    Toast.makeText(getBaseContext(), e.getMessage(), Toast.LENGTH_LONG).show();
                }
                finish();

            }
        });
    }
}

我对android开发非常陌生，关于如何改进代码的任何提示将不胜感激:)