java - 扩展 AppCompatButton 的自定义按钮引发强制转换错误

Question

我尝试制作一个扩展 AppCompatButton 的自定义按钮，但应用程序崩溃了。我使用的是 ButtonState 的一个版本，它内部有一个 AppCompatButton 对象以及一个 int 来保存状态，但我发现我可以扩展 AppCompatButton，这样我就不必像这样调用我的按钮 buttonstate.button。 method()，而是可以直接使用按钮 button.method() 以及使用额外变量来操作按钮状态的好处。

ButtonState.java

package com.example.detetiveinvestigativo.Interface.CharacterSelection;

import android.content.Context;

import androidx.annotation.NonNull;
import androidx.appcompat.widget.AppCompatButton;

class ButtonState extends AppCompatButton{
    static final int NOT_SELECTED=0, SELECTED=1, CHARACTER_DEAD=2;
    int state;

    ButtonState(@NonNull Context c) {
        super(c);
        state = NOT_SELECTED;
    }
}

Fragment.java

import android.content.Context;
import android.graphics.Color;
import android.os.Bundle;

import androidx.appcompat.widget.AppCompatButton;
import androidx.appcompat.widget.AppCompatTextView;
import androidx.core.content.ContextCompat;
import androidx.fragment.app.Fragment;

import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;

import com.example.detetiveinvestigativo.DataManager.Entity;
import com.example.detetiveinvestigativo.Events.EventCharacterSelect;
import com.example.detetiveinvestigativo.Events.EventSwapFragment;
import com.example.detetiveinvestigativo.Game.Game;
import com.example.detetiveinvestigativo.Game.Register;
import com.example.detetiveinvestigativo.R;
import com.example.detetiveinvestigativo.Utilities.MyDrawableCompat;

import org.greenrobot.eventbus.EventBus;
import org.greenrobot.eventbus.Subscribe;
import org.greenrobot.eventbus.ThreadMode;

import java.util.ArrayList;

import javax.annotation.Nonnegative;

public class CharacterSelectionFragment extends Fragment {
    private static final String TAG = "CharacterSelectionFrag";
    private static final int NONE=-1, JAILOR=0, MAGE=1, REPORTER=2, GUMSHOE=3, NURSE=4, BODYGUARD=5, WATCHMAN=6,
            PARTY_HARD=7, VETERAN=8;
    private Context c;
    private View v;
    private AppCompatTextView title;
    private ButtonState[] buttonArray;
    private AppCompatButton buttonReviewEvidences;
    private AppCompatButton buttonProceed;
    private int last_char_selected;
    private int total_char_selected; // How many characters are selectedCharacter
    private ArrayList<Register> actionsArray;
    private Game currentGame;


    public CharacterSelectionFragment() { }

    @Override
    public void onStart() {
        super.onStart();
        if(!EventBus.getDefault().isRegistered(this)) EventBus.getDefault().register(this);
    }

    @Override
    public void onStop() {
        super.onStop();
        if(EventBus.getDefault().isRegistered(this)) EventBus.getDefault().unregister(this);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        v = inflater.inflate(R.layout.fragment_character_selection, container, false);
        c = v.getContext();
        findViewsById();
        return v;
    }

    private void findViewsById(){
        if(buttonArray == null) buttonArray = new ButtonState[9];
        for(int i=0; i<buttonArray.length; i++) buttonArray[i] = new ButtonState(c);
        buttonArray[JAILOR]     = v.findViewById(R.id.cs_button_jailor); // <-- Error happens here "cannot cast AppCompatButton to ButtonState"
        buttonArray[MAGE]       = v.findViewById(R.id.cs_button_mage);
        buttonArray[REPORTER]   = v.findViewById(R.id.cs_button_reporter);
        buttonArray[GUMSHOE]    = v.findViewById(R.id.cs_button_gumshoe);
        buttonArray[NURSE]      = v.findViewById(R.id.cs_button_nurse);
        buttonArray[BODYGUARD]  = v.findViewById(R.id.cs_button_bodyguard);
        buttonArray[WATCHMAN]   = v.findViewById(R.id.cs_button_watchman);
        buttonArray[PARTY_HARD] = v.findViewById(R.id.cs_button_party_hard);
        buttonArray[VETERAN]    = v.findViewById(R.id.cs_button_veteran);
        buttonReviewEvidences   = v.findViewById(R.id.cs_button_review_evidences);
        buttonProceed           = v.findViewById(R.id.cs_button_proceed);
        title                   = v.findViewById(R.id.cs_textview_title);
    }

    /*... More methods below ...*/
}

frag_layout.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.appcompat.widget.LinearLayoutCompat xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:orientation="vertical"
    tools:context=".Interface.CharacterSelection.CharacterSelectionFragment"
    android:paddingLeft="16dp"
    android:paddingRight="16dp"
    android:paddingTop="7dp"
    android:paddingBottom="7dp"
    android:background="@drawable/wood_texture"
    android:clickable="true"
    android:focusable="false"
    android:id="@+id/cs_parent_layout">

<!-- ... More buttons above ... -->

    <androidx.appcompat.widget.AppCompatButton
        android:id="@+id/cs_button_jailor"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="10"
        android:text="@string/jailor"
        android:textSize="16.5sp"
        android:fontFamily="@font/joystix_monospace"/>

<!-- ... More buttons below ... -->
</androidx.appcompat.widget.LinearLayoutCompat>

异常

E/EventBus: Could not dispatch event: class com.example.detetiveinvestigativo.Events.EventSwapFragment to subscribing class class com.example.detetiveinvestigativo.MainActivity
    java.lang.ClassCastException: androidx.appcompat.widget.AppCompatButton cannot be cast to com.example.detetiveinvestigativo.Interface.CharacterSelection.ButtonState
        at com.example.detetiveinvestigativo.Interface.CharacterSelection.CharacterSelectionFragment.findViewsById(CharacterSelectionFragment.java:98)
        at com.example.detetiveinvestigativo.Interface.CharacterSelection.CharacterSelectionFragment.onCreateView(CharacterSelectionFragment.java:89)
        at androidx.fragment.app.Fragment.performCreateView(Fragment.java:2600)
        at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:881)
        at androidx.fragment.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManagerImpl.java:1238)
        at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:1303)
        at androidx.fragment.app.BackStackRecord.executeOps(BackStackRecord.java:439)
        at androidx.fragment.app.FragmentManagerImpl.executeOps(FragmentManagerImpl.java:2079)
        at androidx.fragment.app.FragmentManagerImpl.executeOpsTogether(FragmentManagerImpl.java:1869)
        at androidx.fragment.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManagerImpl.java:1824)
        at androidx.fragment.app.FragmentManagerImpl.execPendingActions(FragmentManagerImpl.java:1727)
        at androidx.fragment.app.FragmentManagerImpl.executePendingTransactions(FragmentManagerImpl.java:183)
        at com.example.detetiveinvestigativo.MainActivity.swapFragments(MainActivity.java:247)
        at com.example.detetiveinvestigativo.MainActivity.onEvent(MainActivity.java:294)
        at java.lang.reflect.Method.invoke(Native Method)
        at org.greenrobot.eventbus.EventBus.invokeSubscriber(EventBus.java:507)
        at org.greenrobot.eventbus.EventBus.postToSubscription(EventBus.java:434)
        at org.greenrobot.eventbus.EventBus.postSingleEventForEventType(EventBus.java:411)
        at org.greenrobot.eventbus.EventBus.postSingleEvent(EventBus.java:384)
        at org.greenrobot.eventbus.EventBus.post(EventBus.java:265)
        at com.example.detetiveinvestigativo.Interface.Menu.MenuFragment$1.onClick(MenuFragment.java:53)
        at android.view.View.performClick(View.java:7125)
        at android.view.View.performClickInternal(View.java:7102)
        at android.view.View.access$3500(View.java:801)
        at android.view.View$PerformClick.run(View.java:27336)
        at android.os.Handler.handleCallback(Handler.java:883)
        at android.os.Handler.dispatchMessage(Handler.java:100)
        at android.os.Looper.loop(Looper.java:214)
        at android.app.ActivityThread.main(ActivityThread.java:7356)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)

我尝试使用此方法来强制转换按钮，但没有任何改变，引发了相同的异常。

buttonArray[JAILOR] = (ButtonState)v.findViewById(R.id.cs_button_jailor);

如何使 Actor 阵容有效(隐式或非隐式)？

编辑

如果您遇到与我相同的问题，请在下面查看我自己的答案，修复就在那里。

Answer 1

我通过在 ButtonState 类中插入另外两个构造函数，并将 xml 从 AppCompatButton 更改为 ButtonState 来修复它，现在我的自定义按钮类如下所示:

Java

package com.example.detetiveinvestigativo.Interface.CharacterSelection;

import android.content.Context;
import android.util.AttributeSet;

import androidx.annotation.NonNull;
import androidx.appcompat.widget.AppCompatButton;

public class ButtonState extends AppCompatButton {
    static final int NOT_SELECTED=0, SELECTED=1, CHARACTER_DEAD=2;
    int state;

    public ButtonState(@NonNull Context c) {
        super(c);
        state = NOT_SELECTED;
    }

    // Added this constructor here
    public ButtonState(@NonNull Context context, AttributeSet attrs) {
        super(context, attrs);
        state = NOT_SELECTED;
    }

    // And this constructor too
    public ButtonState(@NonNull Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        state = NOT_SELECTED;
    }
}

XML

<?xml version="1.0" encoding="utf-8"?>
<androidx.appcompat.widget.LinearLayoutCompat xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:orientation="vertical"
    tools:context=".Interface.CharacterSelection.CharacterSelectionFragment"
    android:paddingLeft="16dp"
    android:paddingRight="16dp"
    android:paddingTop="7dp"
    android:paddingBottom="7dp"
    android:background="@drawable/wood_texture"
    android:clickable="true"
    android:focusable="false"
    android:id="@+id/cs_parent_layout">

    <com.example.detetiveinvestigativo.Interface.CharacterSelection.ButtonState
        android:id="@+id/cs_button_jailor"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="10"
        android:text="@string/jailor"
        android:textSize="16.5sp"
        android:fontFamily="@font/joystix_monospace"/>

</androidx.appcompat.widget.LinearLayoutCompat>