我试图在Store类中创建一个Item类型的ArrayList，然后在另一个名为StoreTester的类中测试它。我一直收到错误：方法get（）未定义类型Store。所以Java认为我的类型为Store的测试对象不是ArrayList，即使我试图这样做。 我的Store类构造函数：
import java.util.ArrayList;
public class Store
{
private ArrayList<Item> blockbuster;
public Store(){
blockbuster = new ArrayList<Item>();
}
public void addItem(Item i){
blockbuster.add(i);
}
}
这是我的StoreTester类：
import java.util.ArrayList;
public class StoreTester{
public static void main(String[] args){
Store videostore = new Store();
System.out.print(videostore.toString());
System.out.print(videostore.get(0));
}
}
由于某种原因，videostore.toString（）工作正常并打印出我已添加到其中的对象列表。这是我在Store类中编写的toString方法：
public String toString(){
String item = "Items in store: " + "\n";
for(int j = 0; j < blockbuster.size(); j++){
item = item + blockbuster.get(j).getTitle() + "\n";
}
return item;
}
但是一旦我尝试获取（）索引中的特定对象甚至使用videostore.size（），我得到：方法未定义错误。希望这只是一个语法错误或一些我忽略的简单。任何帮助表示赞赏。
答案 0 :(得分：4)
是的，class BluetoothUtils {
companion object {
var listener: ListenThread? = null
val _UUID = UUID.fromString("a0e7e4c7-0e4e-43b7-9d18-659192512164")
val TAG = "BluetoothUtils"
val receiver = MainBTStatusReceiver()
fun initPairingServer(adapter: BluetoothAdapter){
var mmServerSocket: BluetoothServerSocket?
try {
var tmp = adapter.listenUsingRfcommWithServiceRecord(TAG, _UUID)
mmServerSocket = tmp
listener = ListenThread(mmServerSocket)
listener!!.start()
}catch (ioe: IOException){
Log.e(TAG, "Error initializing Bluetooth", ioe)
}
}
fun cancelListener() = listener!!.cancel()
fun connect(adapter: BluetoothAdapter, device: BluetoothDevice){
var btSocket: BluetoothSocket?
try {
adapter.cancelDiscovery()
btSocket = device.createRfcommSocketToServiceRecord(_UUID)
PairingThread(btSocket).start()
}catch (ioe: IOException){
Log.e(TAG, "error connecting", ioe)
}
}
fun startPair(adapter: BluetoothAdapter, device: BluetoothDevice): Unit{
adapter.cancelDiscovery()
Log.d(TAG, device.bondState.toString())
device.createBond()
}
fun unPair(device: BluetoothDevice): Any = device::class.java.getMethod("removeBond").invoke(device)
}
}
class ListenThread(val btServSock: BluetoothServerSocket) : Thread(){
companion object {
val TAG = "ListenThread"
}
var btSocket: BluetoothSocket? = null
override fun run() {
super.run()
while (true){
try {
Log.d(TAG, "listening . . . ")
btSocket = btServSock.accept()
}catch (ioe: IOException){
Log.e(TAG, "Error", ioe) // SHOULD HANDLE FAILURE OF LISTENER INSTANTIATION
break
}
//manage connection here
//with either BluetoothUtils function
//or BluetoothSocket extension
}
}
fun cancel() = btServSock.close()
}
class PairingThread(val btSocket: BluetoothSocket) : Thread(){
companion object {
val TAG = "Pairing Thread"
}
override fun run() {
super.run()
try {
Log.d(TAG, "attempting to connect")
btSocket.connect()
}catch (ioe: IOException){
Log.e(TAG, "error connecting", ioe)
btSocket.close()
}
}
}
class MainBTStatusReceiver(): BroadcastReceiver(){
val TAG = "MainBTStatusReceiver"
var mAdapter: DeviceAdapter? = null
fun setAdapter(adapter: DeviceAdapter){
mAdapter = adapter
}
override fun onReceive(context: Context?, intent: Intent) {
val action = intent.action
val devExtra = intent.getParcelableExtra<BluetoothDevice>(BluetoothDevice.EXTRA_DEVICE) as BluetoothDevice
when(action){
BluetoothDevice.ACTION_BOND_STATE_CHANGED -> {
val device = intent.getParcelableExtra<BluetoothDevice>(BluetoothDevice.EXTRA_DEVICE)
when(device.bondState){
BluetoothDevice.BOND_BONDED -> {
Log.d(TAG, "BONDED")
}
BluetoothDevice.BOND_BONDING -> {Log.d(TAG, "BONDING")}
BluetoothDevice.BOND_NONE -> {Log.d(TAG, "NONE")}
}
}
}
}
没有方法Store
可以在get中实现
Store public Item get (int index) {
// check for null, then
return blockbuster.get(index);
}
有一个Store它不是ArrayList是一个Store
正如@ElliottFrisch所提到的，你还需要实现ArrayList方法
size