edittext 첫글자 판별하기

public void onTextChanged(CharSequence _param1, int _param2, int _param3, int _param4) {
if(editrext1.getText().toString().length() ==1)
{
if (edittext1.getText().toString().substring((int)(0), (int)(1)).equals("-")) {
SketchwareUtil.showMessage(getApplicationContext(), "-안됨");
}
}
}
@Override
public void beforeTextChanged(CharSequence _param1, int _param2, int _param3, int _param4) {

}

@Override
public void afterTextChanged(Editable _param1) {

}
});
}