Analysis of character filtering function of TextView in Android programming

This article analyzes the character filtering function of TextView in Android programming. Share it for your reference, as follows:

TextView can be set to accept various characters, and filter the specified characters to meet the input and display requirements of different applications.

Configure via xml:

android:InputType

Accept integer input
numberSigned    Accept signed integer input
numberDecimal   Accept inputs to integers and decimals

android:digits

Specify to accept fixed numbers, such as android:digits="012345", only inputs from 0 to 5 numbers are accepted.

android:numberic

integer   Accept integer input
signed    Accept signed integer input
decimal   Accept inputs of integers and decimals

Settings via java code

In fact, the functions of the above three properties are a bit duplicated, and in the end, they all set KeyListener for TextView through Java code.

KeyListener is an interface that provides monitoring of input keyboard keys

InputFilter is an interface that provides filtering characters

Android provides NumberKeyListener that implements KeyListener and InputFilter, while DigitsKeyListener inherits NumberKeyListener

TextView tv = new TextView(context);
//Only accept integer inputKeyListener l = new DigitsKeyListener(fasle,false);
//Accept signed integer inputKeyListener l = new DigitsKeyListener(true,false);
//Accept decimals and integer inputKeyListener l = new DigitsKeyListener(false,true);
//Accept signed integers/decimal inputKeyListener l = new DigitsKeyListener(true,true);
(l);

If you want to achieve greater freedom of filtering customization, you can write a KeyListener (inheriting BaseKeyListener) and implement InputFilter, rewrite the filter() function, and implement free filtering in the filter() function.

I hope this article will be helpful to everyone's Android programming design.