Develop Reference

Update a specific row in a Room Database of Android

I am new to Android and need some help.
I have a listView with some edittext fields and buttons and store the information of the edittext in a room database.
Looks like this: https://imgur.com/a/NTpMUmY
Now, when I change the input of field A to, let's say AAAA, and click on the "button", the room database has to update the row.
My question is when exactly do I call the update command, and how does room know which row has changed? I don't want to update to whole table.
Let me know if I should explain it in another way.

Ok, I found a solution which works for me.
TextWatcher textWatcher = new TextWatcher() {
#Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}
#Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
}
#Override
public void afterTextChanged(Editable s) {
Dao_db.update(s.toString());
}
};
viewHolder.bearbeiten_et.addTextChangedListener(textWatcher);
I use this Textwatcher (didn't know that something like this exist) and update my db when the text changed. :)

Edit text should allow text if a. alphabet +number b. alphabet +special character c. alphabet only

I am trying to generate a regular expression in Android which can satisfy following conditions:
Edit text can accept:
Alphabet only
Combination of Alphabet and number
Combination of Alphabet and special character
Should not accept:
a. Only Number
b. Only Special character
I tried alot but still, i didn't get any meaningful link. Please try to save my day.
I tried with regular expression (?!^\d+$)^.+$") which only valid alphanumric requirement. I am looking for such regular expression which fullfil my requirement.

It's really simple bro... just clear EditText if the text inside it doesn't have an alphabet .. as you have said ...
Should not accept a. Only Number b. Only Special character
TextWatcher mTextWatcher = new TextWatcher() {
#Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}
#Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
boolean atleastOneAlpha = s.toString().matches(".*[a-zA-Z]+.*");
if (!atleastOneAlpha) {
editText.setText("");
}
}
#Override
public void afterTextChanged(Editable s) {
}
};
mTargetEditText.addTextChangedListener(mTextWatcher);

Removing TextChangedListener then re-adding it

So I've been trying to implement the TextWatcher for Android and ran into a few problems with the TextChangedListener being called multiple times or going into an infinite loop as I want to convert the text in the EditText widget into a currency formatted string.
What I did to work around this was create my own custom TextWatcher and then in the afterTextChanged event did something like the following
public class CurrencyTextWatcher implements TextWatcher {
private EditText et;
public CurrencyTextWatcher(EditText editText) {
et = editText;
}
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}
public void onTextChanged(CharSequence s, int start, int before, int count) {
}
public void afterTextChanged(Editable s) {
et.removeTextChangedListener(this);
et.setText(myCurrencyString);
et.addTextChangedListener(this);
}
}
So my question is, is there a better way of doing this? I want to have the one EditText Widget to hold where the edits go and the resulting formatted string.
Also is there actually any other issues that comes about removing and then adding a TextChangedListener like this?
Thanks in advance

Everytime you will update (by eg calling set text) your editText the afterTextChanged will be called, so I think you should refrain from calling setText every time you are in afterTextChanged and only call it when something is really changing.
sth like this
if ( !myCurrencyString.equals(et.getText()))
{
et.setText(myCurrencyString);
}

How about following.
private void resetAddTagField() {
if (edtView != null && textWatcherListener != null) {
edtView.removeTextChangedListener(textWatcherListener);
edtView.setText(DEFAULT_TEXT);
edtView.addTextChangedListener(textWatcherListener);
}
}
What I learn: Do not underestimate power of TextWatcher :D :D

quick search within app in android?

I have a application already working fine. I need to implement a quick search feature to it. Quick search i mean as the users types in every single character i want to result to be fetched. My Activity is a list activity for which the data is coming from the database query. Say the list view has 50 items, and when the user searches with word as "test" I want to query the database and filter the items and display it in the same list view. Something like the contact search in android. Please let me know how to implement this. A quick sample would be help full. Thank you.

you can do by this

I implemented this feature in one of my previous app. The entire code is too long to be pasted here. So, I have posted some portions of it. You may read a bit about the approach used by me and get it done for your app.
EditText filterText;
words = new MySimpleCursorAdapter(Main.this, R.layout.emptylist, temp, from, to);
filterText= (EditText) findViewById(R.id.search_box);
filterText.addTextChangedListener(filterTextWatcher);
words.setFilterQueryProvider(new FilterQueryProvider() {
#Override
public Cursor runQuery(CharSequence constraint) {
Cursor cur=mDbHelper.fetchSugNotes(filterText.getText().toString());
return cur;
}
});
private TextWatcher filterTextWatcher = new TextWatcher() {
public void afterTextChanged(android.text.Editable s) {
};
public void beforeTextChanged(CharSequence s, int start, int count, int after) {};
public void onTextChanged(CharSequence s, int start, int before, int count) {
words.getFilter().filter(s.toString());
};
};

show data in listview from webservice according to keypress in android

I am developing an android app for a Korean client. I have to search a data according to key press, like, if I press A then all the data who started from A show in listview where data come from a web service in listview. Is it possible?
If yes, then how to do it. If possible give me some code or link which I can use?
Thanks.

Yes its possible.You can add TextChangedListener on your edittext and in the onTextChanged event get the date from the webserver as json or xml and parse that data and show the data in a listview.
edittext.addTextChangedListener(textWacther);
final TextWatcher textWacther = new TextWatcher() {
public void afterTextChanged(Editable s) {
}
public void beforeTextChanged(CharSequence s, int start, int count,
int after) {
}
public void onTextChanged(CharSequence s, int start, int before,
int count) {
getdata();
}
};
Getting the data from webserver this question might be helpful for you
How to connect to a Remote Database with Webservices?

At the area where getData() is called in #Syam's code, fetch the new data according to the text entered in the edit text, put it in the array that has the source of ListView, don't forget to call setDataSetChanged() on the adapter in the end.