在Kotlin的两个活动之间传递一个对象实例
我想知道是否有人可以帮助我解决与意图这个错误？
我有2个活动之间的连接：第一个活动网格视图“MainActivity.kt”，第二个列表视图“Main2Activity.kt”，我有2个对象实例（adapter1，adapter2）从“Main2Activity.kt”，我想单击“MainActivity.kt”中的特定图像时，传递特定对象实例（adapter1）或（adapter2）
注意：我正在使用BaseAdapter
这是一个MainActivity.kt
class MainActivity : AppCompatActivity() { var adapter:FoodAdapter?=null var listOfFoods =ArrayList<Food>() override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(layout.activity_main) // load foods listOfFoods.add(Food("Coffee"," Coffee preparation is", a)) listOfFoods.add(Food("Coffee"," Coffee preparation is", b)) listOfFoods.add(Food("Coffee"," Coffee preparation is", c)) listOfFoods.add(Food("Coffee"," Coffee preparation is", d)) adapter= FoodAdapter(this,listOfFoods) gvListFood.adapter =adapter } class FoodAdapter: BaseAdapter { var listOfFood= ArrayList<Food>() var context: Context?=null constructor(context:Context,listOfFood:ArrayList<Food>):super(){ this.context=context this.listOfFood=listOfFood } override fun getView(p0: Int, p1: View?, p2: ViewGroup?): View? { val food = this.listOfFood[p0] var inflator = context!!.getSystemService(Context.LAYOUT_INFLATER_SERVICE) as LayoutInflater var foodView= inflator.inflate(layout.food_ticket,null) foodView.ivFoodImage.setImageResource(food.image!!) foodView.ivFoodImage.setOnClickListener { if (foodView.ivFoodImage.context!!.equals(a) ) { val intent = Intent(context, Main2Activity::class.java) intent.putExtra(Main2Activity.EXTRA_ADAPTER_MODE, AdapterType.ADAPTER_TYPE_2.ordinal) intent.putExtra("name", food.name!!) intent.putExtra("des", food.des!!) intent.putExtra("image", food.image!!) context!!.startActivity(intent) } else if (foodView.ivFoodImage.context!!.equals(b)) { val intent = Intent(context, Main2Activity::class.java) intent.putExtra(Main2Activity.EXTRA_ADAPTER_MODE, AdapterType.ADAPTER_TYPE_2.ordinal) intent.putExtra("name", food.name!!) intent.putExtra("des", food.des!!) intent.putExtra("image", food.image!!) context!!.startActivity(intent) } } return foodView } override fun getItem(p0: Int): Any { return listOfFood[p0] } override fun getItemId(p0: Int): Long { return p0.toLong() } override fun getCount(): Int { return listOfFood.size } } } 这是一个Main2Activity.kt
class Main2Activity : AppCompatActivity() { companion object { val EXTRA_ADAPTER_MODE = "extra_adapter_mode" } var adapter1: FoodAdapter? = null var adapter2: FoodAdapter2? = null var listOfFoods2 = ArrayList<Food>() var listOfFoods3 = ArrayList<Food>() override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main2) val bundle = intent?.getIntExtra(EXTRA_ADAPTER_MODE, AdapterType.ADAPTER_TYPE_1.ordinal) val name = bundle?.let { AdapterType.fromOrdinal(it) } val des = bundle?.let { AdapterType.fromOrdinal(it) } val image = bundle?.let { AdapterType.fromOrdinal(it) } //val bundle = intent.extras //val name = bundle.getString("name") //val des = bundle.getString("des") //val image = bundle.getInt("image") /* ivFoodImage2?.let { it.setImageResource(image) } tvName2?.let { it.text = name } tvDes2?.let { it.text = des } */ // load foods2 listOfFoods2.add(Food("Coffee", " Coffee1 preparation is", R.drawable.a)) listOfFoods2.add(Food("Coffee", " Coffee2 preparation is", R.drawable.b)) //listOfFoods2.add(Food("Coffee"," Coffee preparation is",R.drawable.c)) //listOfFoods2.add(Food("Coffee"," Coffee preparation is",R.drawable.d)) // load foods3 //listOfFoods3.add(Food("Coffee"," Coffee preparation is",R.drawable.a)) //listOfFoods3.add(Food("Coffee"," Coffee preparation is",R.drawable.b)) listOfFoods3.add(Food("Coffee", " Coffee3 preparation is", R.drawable.c)) listOfFoods3.add(Food("Coffee", " Coffee4 preparation is", R.drawable.d)) if(adapter1 ==lvFoods2.adapter) { adapter1 = FoodAdapter(listOfFoods2, this) lvFoods2.adapter = adapter1 } else if (adapter2==lvFoods2.adapter) { adapter2 = FoodAdapter2(listOfFoods3, this) lvFoods2.adapter = adapter2 } } class FoodAdapter : BaseAdapter { var context: Context? = null var listOfFoodsLocal2 = ArrayList<Food>() constructor(listOfFoods2: ArrayList<Food>, context: Context) : super() { this.listOfFoodsLocal2 = listOfFoods2 this.context = context } override fun getView(p0: Int, p1: View?, p2: ViewGroup?): View { val food = this.listOfFoodsLocal2[p0] var inflator = context!!.getSystemService(Context.LAYOUT_INFLATER_SERVICE) as LayoutInflater val foodView = inflator.inflate(R.layout.food_ticket2, null) foodView.ivFoodImage2?.let { it.setImageResource(food.image!!) } foodView.tvName2?.let { it.text = food.name!! } foodView.tvDes2?.let { it.text = food.des!! } foodView.ivFoodImage2.setOnClickListener { //move to next val intent = Intent(context, FoodDetails::class.java) intent.putExtra("name", food.name!!) intent.putExtra("des", food.des!!) intent.putExtra("image", food.image!!) context!!.startActivity(intent) } return foodView } override fun getItem(p0: Int): Any { return listOfFoodsLocal2[p0] } override fun getItemId(p0: Int): Long { return p0.toLong() } override fun getCount(): Int { return listOfFoodsLocal2.size } } class FoodAdapter2 : BaseAdapter { var context: Context? = null var listOfFoodsLocal3 = ArrayList<Food>() constructor(listOfFoods3: ArrayList<Food>, context: Context) : super() { this.listOfFoodsLocal3 = listOfFoods3 this.context = context } override fun getView(p0: Int, p1: View?, p2: ViewGroup?): View { val food = this.listOfFoodsLocal3[p0] var inflator = context!!.getSystemService(Context.LAYOUT_INFLATER_SERVICE) as LayoutInflater val foodView = inflator.inflate(R.layout.food_ticket2, null) foodView.ivFoodImage2?.let { it.setImageResource(food.image!!) } foodView.tvName2?.let { it.text = food.name!! } foodView.tvDes2?.let { it.text = food.des!! } foodView.ivFoodImage2.setOnClickListener { //move to next val intent = Intent(context, FoodDetails::class.java) intent.putExtra("name", food.name!!) intent.putExtra("des", food.des!!) intent.putExtra("image", food.image!!) context!!.startActivity(intent) } return foodView } override fun getItem(p0: Int): Any { return listOfFoodsLocal3[p0] } override fun getItemId(p0: Int): Long { return p0.toLong() } override fun getCount(): Int { return listOfFoodsLocal3.size } } }
这里是枚举类
enum class AdapterType { ADAPTER_TYPE_1, ADAPTER_TYPE_2, ADAPTER_TYPE_3; companion object { fun fromOrdinal(name:String,des:String,image: Int): AdapterType? { return AdapterType.values().firstOrNull { it.ordinal == image} } } }
创建一个IntDef，如：
@Retention(SOURCE) @IntDef({ADAPTER_MODE_1, ADAPTER_MODE_2, ADAPTER_MODE_3}) public @interface AdapterMode {} public static final int ADAPTER_MODE_1 = 0; public static final int ADAPTER_MODE_2 = 1; public static final int ADAPTER_MODE_3 = 2; //...
并将int添加到包中。 对于Kotlin，你必须使用伴侣对象来定义变量
class FirstActivity { companion object { val ADAPTER_MODE1 = 0 val ADAPTER_MODE2 = 1 val ADAPTER_MODE3 = 2 //... } }
所以你可以传递无限的适配器到你的第二个活动
编辑 ：Kotlin 不支持 @IntDef，所以你应该使用一个枚举：
enum class AdapterType { ADAPTER_TYPE_1, ADAPTER_TYPE_2, ADAPTER_TYPE_3; companion object { fun fromOrdinal(ordinal: Int): AdapterType? { return AdapterType.values().firstOrNull { it.ordinal == ordinal } } } }
然后像这样使用它：
class FirstActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) val intent = Intent(this, SecondActivity::class.java) intent.putExtra(SecondActivity.EXTRA_ADAPTER_MODE, AdapterType.ADAPTER_TYPE_2.ordinal) } }
并检索它像：
class SecondActivity : AppCompatActivity() { companion object { val EXTRA_ADAPTER_MODE = "extra_adapter_mode" } override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) //... val adapterTypeOrdinal = intent?.getIntExtra(EXTRA_ADAPTER_MODE, AdapterType.ADAPTER_TYPE_1.ordinal) val adapterType = adapterTypeOrdinal?.let { AdapterType.fromOrdinal(it) } // do something with it } }
活动之间不能通过适配器。 谷歌推荐至少以一种干净的方式。 适配器既不实现Parcelable也不实现Serializable接口。 正如Nino Handler指出的那样，一般的规则是使用Intent发送数据 （不是适配器本身），这些数据应该用来创建适配器。