Android Java，setOnTouchListener 每 0.25 秒从字符串中删除 1 个最后一个字符

Question

I am making calculator on java. I want to make a button, which corresponds to delete the last character.
If you press on it for 1 second, it starts to delete 1 character every 0.25s form EditText string.

Clear button:

clear.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            if(operation.length() != 0){
                String s=operation.getText().toString();
                s = s.substring(0,operation.length()-1);
                operation.setText(s);}
        }
    });

Long touch idea:

clear.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
                return false;
            }
        });

Answer 1

You can use ScheduledExecutorService to schedule Runnables at a set rate and with an initial delay. Here's how I would do it:

// Create member variables for your ExecutorService and ScheduledFuture
private ScheduledExecutorService mExecutor;
private ScheduledFuture<?> mFuture;

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

    final EditText editText = findViewById(R.id.textView);
    final Button button = findViewById(R.id.button2);

    // Set up the ExecutorService
    mExecutor = Executors.newSingleThreadScheduledExecutor();

    final Runnable deleteRunnable = new Runnable() {
        @Override
        public void run() {
            // We'll use the view's post() method
            // to make sure we're updating it from the correct thread
            editText.post(new Runnable() {
                @Override
                public void run() {
                    String textValue = editText.getText().toString();
                    
                    if(textValue.length() > 0){
                        // Delete the last character
                        textValue = textValue.substring(0, textValue.length() - 1);
                        
                        Log.d("MY_LOG_TAG", textValue);
                        editText.setText(textValue);
                    }
                    
                    // (Optionally)
                    // Keep the cursor at the end of the text
                    editText.setSelection(textValue.length());
                }
            });
        }
    };

    button.setOnTouchListener(new View.OnTouchListener() {
        @Override
        public boolean onTouch(View v, MotionEvent event) {
            int action = event.getAction();
            
            switch(action){
                case MotionEvent.ACTION_DOWN:
                    Log.d("MY_LOG_TAG", "Action down");
                    
                    // Schedule the runnable with an initial delay of 1000 milliseconds
                    // and at a rate of 250 milliseconds
                    mFuture = mExecutor.scheduleAtFixedRate(deleteRunnable, 1000, 250, TimeUnit.MILLISECONDS);
                    break;

                case MotionEvent.ACTION_UP:
                    Log.d("MY_LOG_TAG", "Action up");
                    
                    // Cancel the scheduled runnable when the Up event is triggered
                    if(mFuture != null){
                        mFuture.cancel(false);
                    }
                    break;
            }
            return false;
        }
    });
}

@Override
protected void onDestroy() {
    // Shutdown the Executor Service
    mExecutor.shutdown();
    
    super.onDestroy();
}