java.lang.RuntimeException : Parcelable encountered IOException writing serializable object (name = [[Landroid. widget.Button;)

Question

我正在编写一个数独求解器应用程序。然而，由于某种未知原因，它不断崩溃。

当我尝试调试应用程序时，我没有得到具体的一行来告诉我代码中的哪些内容导致了应用程序崩溃。然而，我看到它遍历了整个solverActivity类而没有崩溃，并显示了正确的suoku板大约半秒，然后崩溃了。

我将错误消息解释为好像我试图发送不可序列化的对象(按钮)。但是，我在代码中找不到尝试这样做的地方。

我用谷歌搜索但没有找到任何对我有帮助的解决方案。这促使我写了这篇文章。

这是堆栈跟踪。

2020-03-08 09:40:19.559 15499-15499/com.example.sodukosolver E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.sodukosolver, PID: 15499 java.lang.RuntimeException: Parcelable encountered IOException writing serializable object (name = [[Landroid.widget.Button;) at android.os.Parcel.writeSerializable(Parcel.java:1833) at android.os.Parcel.writeValue(Parcel.java:1780) at android.os.Parcel.writeArrayMapInternal(Parcel.java:928) at android.os.BaseBundle.writeToParcelInner(BaseBundle.java:1584) at android.os.Bundle.writeToParcel(Bundle.java:1253) at android.app.IActivityTaskManager$Stub$Proxy.activityStopped(IActivityTaskManager.java:4505) at android.app.servertransaction.PendingTransactionActions$StopInfo.run(PendingTransactionActions.java:145) at android.os.Handler.handleCallback(Handler.java:883) at android.os.Handler.dispatchMessage(Handler.java:100) at android.os.Looper.loop(Looper.java:214) at android.app.ActivityThread.main(ActivityThread.java:7356) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930) Caused by: java.io.NotSerializableException: androidx.appcompat.widget.AppCompatButton at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1240) at java.io.ObjectOutputStream.writeArray(ObjectOutputStream.java:1434) at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1230) at java.io.ObjectOutputStream.writeArray(ObjectOutputStream.java:1434) at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1230) at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:354) at android.os.Parcel.writeSerializable(Parcel.java:1828) at android.os.Parcel.writeValue(Parcel.java:1780)  at android.os.Parcel.writeArrayMapInternal(Parcel.java:928)  at android.os.BaseBundle.writeToParcelInner(BaseBundle.java:1584)  at android.os.Bundle.writeToParcel(Bundle.java:1253)  at android.app.IActivityTaskManager$Stub$Proxy.activityStopped(IActivityTaskManager.java:4505)  at android.app.servertransaction.PendingTransactionActions$StopInfo.run(PendingTransactionActions.java:145)  at android.os.Handler.handleCallback(Handler.java:883)  at android.os.Handler.dispatchMessage(Handler.java:100)  at android.os.Looper.loop(Looper.java:214)  at android.app.ActivityThread.main(ActivityThread.java:7356)  at java.lang.reflect.Method.invoke(Native Method)  at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930) 

这是我的 MainActivity，我认为它工作得很好(很抱歉没有遵循 CLEAN CODE :/)。

import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.Spinner;
import java.util.HashMap;

public class MainActivity extends AppCompatActivity implements AdapterView.OnItemSelectedListener {

    private Button[][] verticalButtons = new Button[9][9];
    private Button[][] landscapeButtons = new Button[9][9];
    private Button solveButton, clearButton;
    private HashMap<String, Integer> solveMap = new HashMap<>();
    private Spinner spinner;
    private String number;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        spinner = findViewById(R.id.number_spinner);
        ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this, R.array.numbers, android.R.layout.simple_spinner_item);
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        spinner.setAdapter(adapter);
        spinner.setOnItemSelectedListener(this);

        solveButton = findViewById(R.id.solve_button);
        clearButton = findViewById(R.id.clear_button);
        solveButton.setOnClickListener(v -> loadResult());

        if(savedInstanceState != null && getResources().getConfiguration().orientation == Configuration.ORIENTATION_PORTRAIT){
            solveMap = (HashMap<String, Integer>) savedInstanceState.getSerializable("solveMap");
            verticalButtons = findButtons(verticalButtons,"button", false);
            clearButton.setOnClickListener(v -> clearAllButtons(verticalButtons));
            loadButtonValue(verticalButtons);
        }
        else if(savedInstanceState != null && getResources().getConfiguration().orientation == Configuration.ORIENTATION_LANDSCAPE){
            solveMap = (HashMap<String, Integer>) savedInstanceState.getSerializable("solveMap");
            landscapeButtons = findButtons(landscapeButtons,"buttons", false);
            clearButton.setOnClickListener(v -> clearAllButtons(landscapeButtons));
            loadButtonValue(landscapeButtons);
        }
        else if(savedInstanceState == null && getResources().getConfiguration().orientation == Configuration.ORIENTATION_PORTRAIT){
            verticalButtons = findButtons(verticalButtons,"button", true);
            clearButton.setOnClickListener(v -> clearAllButtons(verticalButtons));
        }else{
            landscapeButtons = findButtons(landscapeButtons,"buttons", true);
            clearButton.setOnClickListener(v -> clearAllButtons(landscapeButtons));
        }
    }

    /**
     * This method finds the buttons of the board based after the orientation of the device
     * @param sudokuButtons 2D Array of Buttons[9][9]
     * @param orientation String referring to xml id, button = PORTRAIT(xml), buttons = LANDSCAPE(xml)
     * @param boardIsEmpty boolean used to determine if code is being created for the first time or being recreated
     * @return a 2D Array of buttons[9][9]
     */
    private Button[][] findButtons(Button[][] sudokuButtons, String orientation, boolean boardIsEmpty){
        for(int i = 0; i < 9; i++)
            for (int j = 0; j < 9; j++){
                String buttonID = orientation + i + j;
                int resId = getResources().getIdentifier(buttonID, "id", getPackageName());
                sudokuButtons[i][j] = findViewById(resId);
                sudokuButtons[i][j].setOnClickListener(v -> updateButtonValue(v));

                if(boardIsEmpty) {
                    solveMap.put("key" + i + j , 0);
                }
            }
        return sudokuButtons;
    }

    /**
     * This method updates the values in a button after it has been clicked
     * @param view
     */
    private void updateButtonValue(View view){
        Button button = findViewById(view.getId());
        String buttonName = getResources().getResourceEntryName(view.getId());
        String numberString = buttonName.replaceAll("\\D+","");
        if(number.equals("Select a number")) {
            button.setText("");
            solveMap.put("key" + numberString, 0);
        }
        else {
            button.setText(number);
            solveMap.put("key" + numberString, Integer.valueOf(number));
        }
    }

    /**
     * This method recreates the board after the device's orientation has changed
     * @param sudukoButtons Empty 2D Array of buttons
     */
    private void loadButtonValue(Button[][] sudukoButtons) {
        for (int i = 0; i < 9; i++)
            for (int j = 0; j < 9; j++) {
                String number = String.valueOf(solveMap.get("key" + i + j));
                if (number.equals("0"))
                    sudukoButtons[i][j].setText("");
                else
                    sudukoButtons[i][j].setText(number);
            }
    }

    /**
     * This method changes the activity and sends some parameters to the next activity
     */
    private void loadResult(){
        long time = System.currentTimeMillis();
        int [][] resultBoard = new int[9][9];
        resultBoard = populateBoard(resultBoard);
        Intent intent = new Intent(this, SolverActivity.class);
        Bundle bundle = new Bundle();
        bundle.putSerializable("board", resultBoard);
        intent.putExtras(bundle);
        intent.putExtra("start", time);
        startActivity(intent);
    }

    /**
     * This method retrieves all the values from the buttons and places them in a 2D Array of the type int
     * @param resultBoard Empty 2D Array
     * @return A populated 2D Array, which the user wants to have solved
     */
    private int[][] populateBoard(int[][] resultBoard){
        for (int i = 0; i < 9; i++) {
            for (int j = 0; j < 9; j++) {
                int number = solveMap.get("key" + i + j);
                resultBoard[i][j] = number;
            }
        }
        return resultBoard;
    }

    /**
     * Clears all the buttons according the device orientation
     * @param sudokuButtons 2D Array of Buttons which is linked to xml file (PORTRAIT or LANDSCAPE)
     */
    private void clearAllButtons(Button[][] sudokuButtons){
        solveMap.clear();
        for (int i = 0; i < 9; i++) {
            for (int j = 0; j < 9; j++) {
                sudokuButtons[i][j].setText("");
                solveMap.put("key" + i + j, 0);
            }
        }
    }

    @Override
    protected void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        outState.putSerializable("solveMap", solveMap);
        outState.putSerializable("verticalButtons", verticalButtons);
        outState.putSerializable("landscapeButtons", landscapeButtons);
    }

    @Override
    public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
        this.number = parent.getItemAtPosition(position).toString();
    }

    @Override
    public void onNothingSelected(AdapterView<?> parent) {

    }
}

这是我的 SolverActivity，我认为它导致了问题(很抱歉 onCreate 时间太长，我计划在解决这个问题后重构该类)。

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.Button;
import android.widget.TextView;

public class SolverActivity extends AppCompatActivity {

    private Button[][] buttons = new Button [9][9];
    private Button backButton;
    private int[][] board, solvedBoard;
    private TextView timeView;
    private long test;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_solver);
        timeView = findViewById(R.id.result_time);
        backButton = findViewById(R.id.back_button);
        backButton.setOnClickListener(v -> onBackPressed());

        board = (int[][]) getIntent().getExtras().getSerializable("board");
        long time = getIntent().getLongExtra("start", 0);

        if(savedInstanceState == null) {
            SudokuSolver sudokuSolver = new SudokuSolver(board);
            if (sudokuSolver.solve())
                solvedBoard = sudokuSolver.getBoard();
            else
                solvedBoard = new int[9][9];
        }
        else{
            solvedBoard = (int[][]) savedInstanceState.getSerializable("solvedBoard");
        }

        for (int i = 0; i < 9; i++) {
            for (int j = 0; j < 9; j++) {
                String buttonId = "button" + i + j;
                int resId = getResources().getIdentifier(buttonId, "id", getPackageName());
                buttons[i][j] = findViewById(resId);
                buttons[i][j].setText(String.valueOf(solvedBoard[i][j]));

            }
        }
        if (savedInstanceState == null)
            test = System.currentTimeMillis();
        else
            test = savedInstanceState.getLong("test");
        long stop = test - time;
        timeView.append(stop + "ms");

    }

    @Override
    public void onSaveInstanceState(@NonNull Bundle outState) {
        super.onSaveInstanceState(outState);
        outState.putSerializable("solvedBoard", solvedBoard);
        outState.putLong("test", test);
    }
}

Answer 1

我找到了导致我的应用崩溃的原因，如果其他人可能遇到类似的问题，我想分享我的解决方案。

@Override
protected void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
    outState.putSerializable("solveMap", solveMap);
    // The two lines beneath caused the app to crash
    outState.putSerializable("verticalButtons", verticalButtons);
    outState.putSerializable("landscapeButtons", landscapeButtons);
}

我什至不知道，为什么我一开始就有这些，因为没有使用过。无论如何，因为我不需要它们，所以只是删除了这两行，使其看起来像这样。

@Override
protected void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
    outState.putSerializable("solveMap", solveMap);
}

我认为导致问题的原因是以这种方式保存按钮的二维数组。对于有类似问题的人，我建议您检查一下 OnsaveInstanceState 中的保存方式。