来自C＃的Kotlin新手。
我正在尝试创建一个通过泛型接受可互换类对象的类。在类中，我想访问类中的属性值和调用方法。我认为这必须通过某种反射机制。通过Kotlin引用挖掘我一直在尝试将建议应用到我的代码中，但是我得到了一些神秘的错误。
感谢任何帮助。
public class Activity_Ascolta extends AppCompatActivity {
final Context context = this;
int flag = 0;
final MediaPlayer [] mpList = new MediaPlayer[50];
float volumecorrente = (float) (1 - (Math.log(100 - 50) / Math.log(100)));
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//Remove title bar
this.requestWindowFeature(Window.FEATURE_NO_TITLE);
//Remove notification bar
this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
//set content view AFTER ABOVE sequence (to avoid crash)
this.setContentView(R.layout.layout_ascolta);
setContentView(R.layout.layout_ascolta);
final int MAX_VOLUME = 100;
SeekBar seekBar = (SeekBar) findViewById(R.id.sb_volume);
seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
@Override
public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
float volume = (float) (1 - (Math.log(MAX_VOLUME - progress) / Math.log(MAX_VOLUME)));
mpList[flag].setVolume(volume, volume);
volumecorrente = volume;
}
@Override
public void onStartTrackingTouch(SeekBar seekBar) {
}
@Override
public void onStopTrackingTouch(SeekBar seekBar) {
}
});
TextView tv_sopra = (TextView) findViewById(R.id.tv_ascolta_1);
TextView tv_sotto = (TextView) findViewById(R.id.tv_ascolta_2);
TextView tv_apprezza = (TextView) findViewById(R.id.tv_ascolta_3);
SharedPreferences scelta_lingua = getSharedPreferences("pref_lingua", context.MODE_PRIVATE);
final SharedPreferences.Editor editor = scelta_lingua.edit();
String lingua_corrente = scelta_lingua.getString("pref_lingua", "");
if (lingua_corrente.compareTo("italiano") == 0) {
tv_sopra.setText("ASCOLTA");
tv_sotto.setText("LA MUSICA");
tv_apprezza.setText("APPREZZA LE DIFFERENZE DI OGNI CUFFIA");
} else if (lingua_corrente.compareTo("inglese") == 0) {
tv_sopra.setText("LISTEN");
tv_sotto.setText("TO THE MUSIC");
tv_apprezza.setText("APPRECIATES THE DIFFERENCES OF EACH HEADSET");
}
ImageButton returnHome = (ImageButton) findViewById(R.id.img_btt_return_home_ascolto);
returnHome.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if (mpList != null) {mpList[flag].release();}
final Intent toHome = new Intent(Activity_Ascolta.this, Activity_Home.class);
startActivity(toHome);
}
});
ImageButton playMusic = (ImageButton) findViewById(R.id.img_btt_play_music);
playMusic.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
/*final Intent toMediaPlayer = new Intent(Activity_Ascolta.this,Activity_MediaPlayer.class);
startActivity(toMediaPlayer);*/
if (mpList != null) {mpList[flag].release();}
//generate random number
Random randomGenerator = new Random();
int randomInt = randomGenerator.nextInt(mpList.length);
Log.e("Random" , String.valueOf(randomInt));
mpList[randomInt].start();
mpList[randomInt].setVolume(volumecorrente,volumecorrente);
flag = randomInt;
}
});
}
@Override
protected void onStart () {
super.onStart();
loadingSongs();
}
public void loadingSongs (){
mpList [0] = MediaPlayer.create(Activity_Ascolta.this, R.raw.a24k_magic);
mpList [1] = MediaPlayer.create(Activity_Ascolta.this, R.raw.abbaon_fat_tracks);
mpList [2] = MediaPlayer.create(Activity_Ascolta.this, R.raw.after_the_afterlife);
mpList [3] = MediaPlayer.create(Activity_Ascolta.this, R.raw.amalia);
mpList [4] = MediaPlayer.create(Activity_Ascolta.this, R.raw.amerimacka);
mpList [5] = MediaPlayer.create(Activity_Ascolta.this, R.raw.angels);
mpList [6] = MediaPlayer.create(Activity_Ascolta.this, R.raw.anymore);
mpList [7] = MediaPlayer.create(Activity_Ascolta.this, R.raw.baby_gurl_original_mix);
mpList [8] = MediaPlayer.create(Activity_Ascolta.this, R.raw.back_home);
mpList [9] = MediaPlayer.create(Activity_Ascolta.this, R.raw.beautiful_escape_feat_zak_a);
mpList [10] = MediaPlayer.create(Activity_Ascolta.this, R.raw.better_with_you);
mpList [11] = MediaPlayer.create(Activity_Ascolta.this, R.raw.black_jeans_vocal_mix);
mpList [12] = MediaPlayer.create(Activity_Ascolta.this, R.raw.body_music);
mpList [13] = MediaPlayer.create(Activity_Ascolta.this, R.raw.born_to_run);
mpList [14] = MediaPlayer.create(Activity_Ascolta.this, R.raw.brother_john);
mpList [15] = MediaPlayer.create(Activity_Ascolta.this, R.raw.bye_bye_boy);
mpList [16] = MediaPlayer.create(Activity_Ascolta.this, R.raw.cloud_9);
mpList [17] = MediaPlayer.create(Activity_Ascolta.this, R.raw.daddy_s_groove);
mpList [18] = MediaPlayer.create(Activity_Ascolta.this, R.raw.don_t_go);
mpList [19] = MediaPlayer.create(Activity_Ascolta.this, R.raw.down_the_road_irfane_remix);
mpList [20] = MediaPlayer.create(Activity_Ascolta.this, R.raw.down_to_the_sound);
mpList [21] = MediaPlayer.create(Activity_Ascolta.this, R.raw.eye_of_the_tiger);
mpList [22] = MediaPlayer.create(Activity_Ascolta.this, R.raw.fly_feat_kelsey);
mpList [23] = MediaPlayer.create(Activity_Ascolta.this, R.raw.glad_edit);
mpList [24] = MediaPlayer.create(Activity_Ascolta.this, R.raw.i_can_see_clearly_now);
mpList [25] = MediaPlayer.create(Activity_Ascolta.this, R.raw.i_don_t_wanna_live_forever_fifty_shades_darker);
mpList [26] = MediaPlayer.create(Activity_Ascolta.this, R.raw.jump);
mpList [27] = MediaPlayer.create(Activity_Ascolta.this, R.raw.kill_it_tonight_feat_ice_mc);
mpList [28] = MediaPlayer.create(Activity_Ascolta.this, R.raw.kindling_for_the_master_majo);
mpList [29] = MediaPlayer.create(Activity_Ascolta.this, R.raw.lady_divine);
mpList [30] = MediaPlayer.create(Activity_Ascolta.this, R.raw.life_round_here);
mpList [31] = MediaPlayer.create(Activity_Ascolta.this, R.raw.make_you_feel);
mpList [32] = MediaPlayer.create(Activity_Ascolta.this, R.raw.melt_away_original_mix);
mpList [33] = MediaPlayer.create(Activity_Ascolta.this, R.raw.midnight_feast);
mpList [34] = MediaPlayer.create(Activity_Ascolta.this, R.raw.palace_posy);
mpList [35] = MediaPlayer.create(Activity_Ascolta.this, R.raw.pirates_of_samba_oxio_radio);
mpList [36] = MediaPlayer.create(Activity_Ascolta.this, R.raw.pledge_allegiance_the_rimsho);
mpList [37] = MediaPlayer.create(Activity_Ascolta.this, R.raw.queen_of_the_night_feat_nik);
mpList [38] = MediaPlayer.create(Activity_Ascolta.this, R.raw.set_me_free_feat_alexandra_p);
mpList [39] = MediaPlayer.create(Activity_Ascolta.this, R.raw.sister_welcome);
mpList [40] = MediaPlayer.create(Activity_Ascolta.this, R.raw.space_walk);
mpList [41] = MediaPlayer.create(Activity_Ascolta.this, R.raw.the_sweetest);
mpList [42] = MediaPlayer.create(Activity_Ascolta.this, R.raw.to_get_up_with_you_remix);
mpList [43] = MediaPlayer.create(Activity_Ascolta.this, R.raw.towers_feat_szjerdene);
mpList [44] = MediaPlayer.create(Activity_Ascolta.this, R.raw.traveling_miles);
mpList [45] = MediaPlayer.create(Activity_Ascolta.this, R.raw.tricks_main_vocal_original);
mpList [46] = MediaPlayer.create(Activity_Ascolta.this, R.raw.ugly_brotha_real_nices_pri);
mpList [47] = MediaPlayer.create(Activity_Ascolta.this, R.raw.wanting_you);
mpList [48] = MediaPlayer.create(Activity_Ascolta.this, R.raw.we_just_couldnt_say_goodbye);
mpList [49] = MediaPlayer.create(Activity_Ascolta.this, R.raw.you_d_be_so_nice_to_come_home);
return ;
}
}
在修改访问泛型类属性之后，代码看起来像这样，println中有错误：
Error:(35, 20) Kotlin: Unresolved reference. None of the following candidates is applicable because of receiver type mismatch:
@InlineOnly public operator inline fun <T> Lazy<T1?>.getValue(thisRef: Any?, property: KProperty<*>): T1? defined in kotlin
@InlineOnly public operator inline fun <V, V1 : T1?> Map<in String, T1?>.getValue(thisRef: Any?, property: KProperty<*>): T1? defined in kotlin.collections
@SinceKotlin public fun <K, V> Map<Class<T1>, T1?>.getValue(key: Class<T1>): T1? defined in kotlin.collections
@JvmName @InlineOnly public operator inline fun <V> MutableMap<in String, in T1?>.getValue(thisRef: Any?, property: KProperty<*>): T1? defined in kotlin.collections
Error:(75, 20) Kotlin: Expression in a class literal has a nullable type 'T1?', use !! to make the type non-nullable
Error:(75, 35) Kotlin: Type parameter bound for T in val <T : Any> KClass<T>.memberProperties: Collection<KProperty1<T, *>>
is not satisfied: inferred type CapturedTypeConstructor(out T1?) is not a subtype of Any
open class Base<T1, T2> (@Autowired var t2: T2) {
@Autowired var request: T1? = null
inline fun <reified T1: Any> retrieveClass(): T1? {
return request.getValue(T1::class.java)
}
fun endpoint(
@ApiParam(value = "Options", required = true) @Valid @RequestBody
body: T1
): ResponseEntity<MyResponse> {
type1 = body
val obj = retrieveClass()
for (prop in obj::class.memberProperties) {
println("${prop.name} = ${prop.get(obj)}")
}
val usefulResult = obj.usefulMethod()
}
}