问题[activity]

我开始使用视频教程，其中一个问题是当您单击启动新活动的按钮时，模拟器和手机中的程序崩溃。课程本身在这里：https ://neco-desarrollo.es/2021/04/%D1%83%D1%80%D0%BE%D0%BA-18-%D0%BF%D1%80%D0% B0% D0%BA%D1%82%D0%B8%D0%BA%D0%B0-%D0%BA%D0%BE%D0%B4-%D1%83%D1%80%D0%BE%D0% BA% D0%B0

我必须马上说，我阅读了视频上的所有评论，出现了这样的问题，但没有人写出解决方案。

我正在尝试运行的活动代码：

package com.example.practic

import android.os.Bundle
import android.view.View
import androidx.appcompat.app.AppCompatActivity
import com.example.practic.constance.Constance
import com.example.practic.databinding.ActivitySignInUpBinding


class SignInUpActivity : AppCompatActivity() {

    lateinit var bindingClass: ActivitySignInUpBinding
    var signState = "empty"
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        bindingClass = ActivitySignInUpBinding.inflate(layoutInflater)
        setContentView(bindingClass.root)

        signState = intent.getStringExtra(Constance.SIGN_STATE)!!
        if (signState == Constance.SIGN_IN_STATE){
            bindingClass.edName.visibility = View.GONE
            bindingClass.edName2.visibility = View.GONE
            bindingClass.edName3.visibility = View.GONE
            bindingClass.imAvatar.visibility = View.INVISIBLE

        }
    }

    fun onClickDone(view: View){
        if (signState == Constance.SIGN_IN_STATE){
    }
        }

    fun onClickAvatar(view: View){
        bindingClass.imAvatar.visibility = View.VISIBLE
    }

}

我启动的活动代码：

package com.example.practic

import android.content.Intent
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import com.example.practic.constance.Constance
import com.example.practic.databinding.ActivityMainBinding
import com.example.practic.databinding.ActivitySignInUpBinding

class MainActivity : AppCompatActivity() {
    lateinit var bindingClass : ActivityMainBinding
    private var login: String = "empty"
    private var password: String = "empty"
    private var name: String = "empty"
    private var name2: String = "empty"
    private var name3: String = "empty"
    private var avatarImId: Int = 0

    override fun onCreate(s: Bundle?) {
        super.onCreate(s)
        bindingClass = ActivityMainBinding.inflate(layoutInflater)
        setContentView(bindingClass.root)
    }

    override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
        super.onActivityResult(requestCode, resultCode, data)
        if (requestCode == Constance.REQUEST_CODE_SIGN_IN){

        }
        else if (requestCode == Constance.REQUEST_CODE_SIGN_UP){

        }
    }

    fun onClickSignIn (view: View){
        val intent = Intent(this,ActivitySignInUpBinding ::class.java)
        intent.putExtra(Constance.SIGN_STATE, Constance.REQUEST_CODE_SIGN_IN)
        startActivityForResult(intent, Constance.REQUEST_CODE_SIGN_IN)
    }
    fun onClickSignUp (view: View){
        val intent = Intent(this,ActivitySignInUpBinding ::class.java)
        intent.putExtra(Constance.SIGN_STATE, Constance.REQUEST_CODE_SIGN_UP)
        startActivityForResult(intent, Constance.REQUEST_CODE_SIGN_UP)
        }

} 

在清单中，新活动添加了：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.practic">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.Practic">
        <activity
            android:name=".MainActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <activity
            android:name=".SignInUpActivity"
            android:exported="true">
        </activity>



    </application>

</manifest> 

它在 logcat 中给出以下错误：

2022-05-10 00:07:09.044 3574-3600/com.example.practic E/eglCodecCommon: GoldfishAddressSpaceHostMemoryAllocator: ioctl_ping failed for device_type=5, ret=-1
2022-05-10 00:07:15.681 3574-3574/com.example.practic E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.practic, PID: 3574
    java.lang.IllegalStateException: Could not execute method for android:onClick
        at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:446)
        at android.view.View.performClick(View.java:6597)
        at com.google.android.material.button.MaterialButton.performClick(MaterialButton.java:1131)
        at android.view.View.performClickInternal(View.java:6574)
        at android.view.View.access$3100(View.java:778)
        at android.view.View$PerformClick.run(View.java:25885)
        at android.os.Handler.handleCallback(Handler.java:873)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:193)
        at android.app.ActivityThread.main(ActivityThread.java:6669)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
     Caused by: java.lang.reflect.InvocationTargetException
        at java.lang.reflect.Method.invoke(Native Method)
        at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:441)
        at android.view.View.performClick(View.java:6597) 
        at com.google.android.material.button.MaterialButton.performClick(MaterialButton.java:1131) 
        at android.view.View.performClickInternal(View.java:6574) 
        at android.view.View.access$3100(View.java:778) 
        at android.view.View$PerformClick.run(View.java:25885) 
        at android.os.Handler.handleCallback(Handler.java:873) 
        at android.os.Handler.dispatchMessage(Handler.java:99) 
        at android.os.Looper.loop(Looper.java:193) 
        at android.app.ActivityThread.main(ActivityThread.java:6669) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858) 
     Caused by: android.content.ActivityNotFoundException: Unable to find explicit activity class {com.example.practic/com.example.practic.databinding.ActivitySignInUpBinding}; have you declared this activity in your AndroidManifest.xml?
        at android.app.Instrumentation.checkStartActivityResult(Instrumentation.java:2005)
        at android.app.Instrumentation.execStartActivity(Instrumentation.java:1673)
        at android.app.Activity.startActivityForResult(Activity.java:4586)
        at androidx.activity.ComponentActivity.startActivityForResult(ComponentActivity.java:597)
        at android.app.Activity.startActivityForResult(Activity.java:4544)
        at androidx.activity.ComponentActivity.startActivityForResult(ComponentActivity.java:583)
        at com.example.practic.MainActivity.onClickSignIn(MainActivity.kt:39)
        at java.lang.reflect.Method.invoke(Native Method) 
        at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:441) 
        at android.view.View.performClick(View.java:6597) 
        at com.google.android.material.button.MaterialButton.performClick(MaterialButton.java:1131) 
        at android.view.View.performClickInternal(View.java:6574) 
        at android.view.View.access$3100(View.java:778) 
        at android.view.View$PerformClick.run(View.java:25885) 
        at android.os.Handler.handleCallback(Handler.java:873) 
        at android.os.Handler.dispatchMessage(Handler.java:99) 
        at android.os.Looper.loop(Looper.java:193) 
        at android.app.ActivityThread.main(ActivityThread.java:6669) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858) 
2022-05-10 00:07:31.148 3657-3687/com.example.practic E/eglCodecCommon: GoldfishAddressSpaceHostMemoryAllocator: ioctl_ping failed for device_type=5, ret=-1

可能是什么原因以及如何解决？

我在清单中添加了一个活动，修复了点击监听器，但现在出现了以下错误：

 Caused by: java.lang.NullPointerException
        at com.example.practic.SignInUpActivity.onCreate(SignInUpActivity.kt:19)
        at android.app.Activity.performCreate(Activity.java:8051)
        at android.app.Activity.performCreate(Activity.java:8031)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1329)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3608)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3792) 
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:103) 
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135) 
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2210) 
        at android.os.Handler.dispatchMessage(Handler.java:106) 
        at android.os.Looper.loopOnce(Looper.java:201) 
        at android.os.Looper.loop(Looper.java:288) 
        at android.app.ActivityThread.main(ActivityThread.java:7839) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:548) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1003) 

问题出在行 signState = intent.getStringExtra(Constance.SIGN_STATE)!! 当它被删除时，活动开始，但没有必要的编辑。

我更新了 Android Studio，Navigation Drawer Activity 模板也随之更新。当你选择一个菜单项时，使用键盘的片段会发生变化，但是当你使用鼠标或手指时没有任何反应。如何解决这个问题？

如何正确初始化本机循环器（ALooper_addFd(...)），以及如何准确地将输入队列（onInputQueueCreated(...){...AInputQueue_attachLooper(...);...}）与其关联，以便与循环器关联的描述符中数据的到达引发对函数的调用，例如：ALooper_callbackFunc？使用这种方法值得吗？使用调用会不会更快（就程序速度而言ALooper_pollOnce(0,...)）ALooper_pollAll(0,...)？

您好，我在另一个 TextView 上的一个 RecyclerView 上有 2 个 Activity。在 RecyclerView 中，我有 2 个 Items，当点击时，第二个 Activity 被激活，但数据以相同的方式加载，我在服务器上准备了 2 个不同的信息，目前我只能实现加载 1两个按钮，我无法区分它们。其实这是我的问题。

活动 c RecyclerView 。

rivate RecyclerView recyclerView;
private List<Hotel> result;
private HotelAdapter adapter;

private FirebaseDatabase database;
private DatabaseReference reference;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_list);

database = FirebaseDatabase.getInstance();
reference = database.getReference("Hotel");

result = new ArrayList<>();

recyclerView = (RecyclerView) findViewById(R.id.hotel_list);
recyclerView.setHasFixedSize(true);
LinearLayoutManager lin = new LinearLayoutManager(this);
lin.setOrientation(LinearLayoutManager.VERTICAL);

recyclerView.setLayoutManager(lin);

adapter = new HotelAdapter(result);
recyclerView.setAdapter(adapter);

updateList();

}

private void updateList(){
reference.addChildEventListener(new ChildEventListener() {
@Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
result.add(dataSnapshot.getValue(Hotel.class));
adapter.notifyDataSetChanged();
}

@Override
public void onChildChanged(DataSnapshot dataSnapshot, String s) {
Hotel hotel = dataSnapshot.getValue(Hotel.class);

int index = getItemIndex(hotel);

result.set(index, hotel);
adapter.notifyItemChanged(index);

}

@Override
public void onChildRemoved(DataSnapshot dataSnapshot) {

Hotel hotel = dataSnapshot.getValue(Hotel.class);

int index = getItemIndex(hotel);

result.remove(index);
adapter.notifyItemRemoved(index);

}

@Override
public void onChildMoved(DataSnapshot dataSnapshot, String s) {

}

@Override
public void onCancelled(DatabaseError databaseError) {

}
});
}
private int getItemIndex(Hotel hotel){

int index = -1;

for(int i = 0; i < result.size(); i++){
if(result.get(i).key.equals(hotel.key)) {
index = i;
break;
}
}
return index;
}
}

此 Activiti 的适配器

    public class HotelAdapter extends RecyclerView.Adapter<HotelAdapter.UserViewHotel>{

    private List<Hotel> list;

    public HotelAdapter(List<Hotel> list) {
    this.list = list;
    }

    @Override
    public UserViewHotel onCreateViewHolder(ViewGroup parent, int viewType) {
    return new UserViewHotel(LayoutInflater.from(parent.getContext()).inflate(R.layout.view_hotel , parent, false));
    }

    @Override
    public void onBindViewHolder(UserViewHotel holder, final int position) {
    Hotel hotel = list.get(position);

    holder.TvName.setText(hotel.name);
    holder.TvStar.setText("star:"+hotel.star + "");

    holder.itemView.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View view) {
    Intent intent = new Intent(view.getContext(), HotelViewActivity.class);
    intent.putExtra(HotelViewActivity.EXTRA_POS, position);
    view.getContext().startActivity(intent);
    }
    });

    }

    @Override
    public int getItemCount() {
    return list.size();
    }

    class UserViewHotel extends RecyclerView.ViewHolder{

    TextView TvName, TvStar;
    Button btPodrob;

    public UserViewHotel(View itemView) {
    super(itemView);
    TvName = (TextView) itemView.findViewById(R.id.TvName);
    TvStar = (TextView) itemView.findViewById(R.id.TvStar);
    btPodrob = (Button) itemView.findViewById(R.id.btPodrob);

    }
    }
    }

视图活动

public class HotelViewActivity extends AppCompatActivity {

static final String EXTRA_POS = "my_item_position";

private TextView TvDitalicHotel;

private FirebaseDatabase database;
private DatabaseReference reference;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_hotel_view);

int my_item_position = (int) getIntent().getExtras().get(EXTRA_POS);

TvDitalicHotel = (TextView) findViewById(R.id.TvDitalicHotel);

database = FirebaseDatabase.getInstance();
reference = database.getReference("DitalicHotel");

reference.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {

}

@Override
public void onCancelled(DatabaseError databaseError) {

}
});

}
}

如何从一个Activity到另一个进行平稳、更有效的过渡？