Sunday, February 23, 2020

android kotlin - How to filter string

MainActivity.kt

package com.example.jetpack

import android.os.Bundle
import androidx.appcompat.app.AppCompatActivity
import kotlinx.android.synthetic.main.activity_main.*


class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val string = "Lorem Ipsum is simply dummy text of the printing" +
                " and typesetting industry. Lorem Ipsum has been the" +
                " industry's standard dummy text ever since the 1500s," +
                " when an unknown printer took a galley of type" +
                " and scrambled it to make a type specimen book."

        textView.text = string

        // Returns a string containing only those characters
        // from the original string that match the given predicate.

        // Filter digits from string.
        // Return a string with only digits.
        val filteredText = string.filter { it.isDigit() }
        textView.append("\n\nFilter digits.\n")
        textView.append(filteredText)


        // Returns a string containing only those characters from
        // the original string that do not match the given predicate.

        // Filter not digits from string.
        // Return a string without digits
        val filterNotText = string.filterNot{ it.isDigit() }
        textView.append("\n\nFilter not digits.\n")
        textView.append(filterNotText)
    }
}
activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">
    <TextView
        android:id="@+id/textView"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:layout_marginEnd="8dp"
        android:textAppearance="@style/TextAppearance.AppCompat.Large"
        android:textColor="#87413F"
        android:textStyle="normal"
        android:fontFamily="sans-serif-condensed"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
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