Miha-x64

object class BadBackendResponseDeserializer : JsonDeserializer<Any?> {

    // register all adapters you need
    private val gson = GsonBuilder()
            .registerTypeAdapter(Post::class.java, WallPostAdapter)
            .registerTypeAdapter(Attachment::class.java, AttachmentAdapter)
            .registerTypeAdapter(User::class.java, UserAdapter)
            .registerTypeAdapter(Group::class.java, GroupAdapter)
            .create()

Miha-x64

abstract class RetrofitCallback<T> : retrofit2.Callback<T> {

    final override fun onResponse(call: Call<T>, response: Response<T>) =
            if (response.isSuccessful) onSuccess(response.body())
            else
                onError(when (response.code()) {
                    401 -> Failure.Unauthorized()
                    404 -> Failure.NotFound()
                    409 -> Failure.Conflict()
                    500 -> Failure.InternalServerError()

Miha-x64

package net.aquadc.common

import com.google.gson.Gson
import com.google.gson.TypeAdapter
import com.google.gson.TypeAdapterFactory
import com.google.gson.reflect.TypeToken
import java.lang.reflect.ParameterizedType
import java.util.*

/**

Miha-x64

package net.aquadc.common
// Gist: https://gist.github.com/Miha-x64/5f626228b34175f827734596d6701008

import java.util.*

// maps

inline fun <reified K : Enum<K>, V> enumMapOf(): MutableMap<K, V> {
    return EnumMap<K, V>(K::class.java)
}

Miha-x64

import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.NonNull;

public abstract class BundleKey<T> {

    @NonNull final String key;

    BundleKey(@NonNull String key) {
        this.key = key;

Miha-x64

import android.os.Handler;
import android.os.Looper;
import androidx.annotation.WorkerThread;

import java.io.File;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executor;

Miha-x64

package net.aquadc.util;

import java.io.IOException;
import java.io.UncheckedIOException;
import java.util.Iterator;
import java.util.function.Consumer;
import java.util.stream.Stream;

public final class Iterators {
    private Iterators() {}

Miha-x64

package net.aquadc.util;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;

/**
 * For lists with O(n) random-deletion time (array-based lists, like {@link ArrayList}),
 * it's faster to mark items as removed and them sweep them all together.

Miha-x64

// Java(?) way
interface Fraction<E extends Exception> {
    int numerator() throws E;
    int denominator() throws E;
}
class FracStatic implements Fraction<RuntimeException> // don't force catching
class FracSum<E1, E2> implements Fraction<EitherException<E1, E2>> // impossible due to type erasure


// Kotlin, Scala, Rust way

Miha-x64

import java.util.Collection;
import java.util.Comparator;
import java.util.Deque;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import java.util.NavigableSet;
import java.util.Queue;
import java.util.Set;
import java.util.SortedSet;