如何在android上捕获KeyEvents？

Question

我需要监听 EditText 上的事件，

1. 当用户开始输入时
2. 以及当焦点丢失时，

我尝试了这个，但它不起作用。我到底哪里搞错了？

etTo.setOnKeyListener(new OnKeyListener(){

    public boolean onKey(View v, int keyCode, KeyEvent event) {
        if(event.getAction() ==KeyEvent.ACTION_DOWN){
            etTo.setText("");
        }
    return false;
    }           
});

Answer 1

对于第一个，你可以尝试这个：

   myEditText.addTextChangedListener(new TextWatcher() {
 public void afterTextChanged(Editable s) {
   //do something
}

  public void beforeTextChanged(CharSequence s, int start, int count, int after){
   //do something
 }

public void onTextChanged(CharSequence s, int start, int before, int count) { 
   //do something
}
});

对于第二个，你可以尝试这个：

     myEditText.setOnEditorActionListener(new TextView.OnEditorActionListener() {
    @Override
    public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {
        if (actionId == EditorInfo.IME_ACTION_DONE) {

            yourcalc();

            return true;
        }
        return false;
    }
});

Answer 2

尝试

etTo.setOnFocusChangeListener(new OnFocusChangeListener() {

            @Override
            public void onFocusChange(View v, boolean hasFocus) {
                // TODO Auto-generated method stub

            }
        });

用于检查焦点和

etTo.addTextChangedListener(new TextWatcher() {

            @Override
            public void onTextChanged(CharSequence arg0, int arg1, int arg2, int arg3) {
                // TODO user start to typing text

            }

            @Override
            public void beforeTextChanged(CharSequence arg0, int arg1, int arg2,
                    int arg3) {
                // TODO cursor is into the EditText

            }

            @Override
            public void afterTextChanged(Editable arg0) {
                // TODO Auto-generated method stub

            }
        });