Android 应用程序重新打开后崩溃

Question

我不仅是 Android Studio 的新手，而且对于一般编程也是新手(作为一种爱好，我在过去一年左右的时间里一直在慢慢自学)。

我的 Android 应用程序遇到了一个问题，我无法找到答案 - 尽管我知道很多人都问过类似的问题，但我似乎无法充分理解该解决方案以使其适应我的需求特别的问题。编译后，我的应用程序将运行良好，并“正确”执行我希望它执行的所有操作(除了工具栏的一个小问题，但我稍后会讲到，哈哈)。

它没有做的一件事是在我关闭它后正确打开它。我可以转到主屏幕并返回应用程序，但如果我完全关闭应用程序并尝试重新打开，则会显示它“不断停止”。

现在，我认为向您提供我的代码(此应用程序中只有两个 Activity )和我的“logcat”会很有用。不过，我目前正在尝试阅读并了解如何首先检索我的“logcat”哈哈，所以希望我很快就能在这里找到它。

根据我的阅读，我的理解是，我的问题要么是我声明的全局变量，要么是我动态制作按钮时按钮 ID 的问题。我遇到有人对他们的“主题”有疑问，但我无法将其与我的特定立场联系起来。然而，如果其中任何一个是问题，我很难理解问题到底是什么。

这是我的主要 Activity ...

package com.example.getcoins;

import android.content.Intent;
import android.icu.text.DecimalFormat;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.TextView;

import com.jjoe64.graphview.GraphView;
import com.jjoe64.graphview.series.DataPoint;
import com.jjoe64.graphview.series.PointsGraphSeries;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {

    int intialCoins = 21;
    int coins;
    int buttonColor =  android.graphics.Color.rgb(0, 150, 150);
    int textColor =  android.graphics.Color.rgb(255, 255, 255);
    ArrayList<Integer> coinsOverTime = new ArrayList<Integer>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar myToolbar = (Toolbar) findViewById(R.id.my_toolbar);
        setSupportActionBar(myToolbar);

        Intent intent = getIntent();
        coins = intent.getIntExtra("COINS", 1);

        if (intent.getExtras() != null)
        {
            Boolean winner = intent.getBooleanExtra("WINNER", true);
            int gambleamount = intent.getIntExtra("GAMBLE", 1);
            Bundle bundle = intent.getExtras();
            coinsOverTime = bundle.getIntegerArrayList("COIN_HISTORY");

            if (winner == true)
            {
                coins = coins + gambleamount;
                coinsOverTime.add(coins);
            }

            if (winner == false && gambleamount == 1)
            {
                coins = coins;
                coinsOverTime.add(coins);
            }

            else if(winner == false)
            {
                coins = coins - gambleamount;
                coinsOverTime.add(coins);
            }
        }

        else
        {
            coins = intialCoins;
            coinsOverTime.add(coins);
        }

        String number = Integer.toString(coins);
        double amount = Double.parseDouble(number);
        DecimalFormat formatter = new DecimalFormat("#,###");
        String formatted = formatter.format(amount);

        TextView textView = (TextView) findViewById(R.id.textView);
        textView.setText(formatted);

        GraphView graph = (GraphView) findViewById(R.id.graph);
        PointsGraphSeries<DataPoint> series = new PointsGraphSeries<>(generateData());
        graph.addSeries(series);
        series.setShape(PointsGraphSeries.Shape.POINT);
        graph.getViewport().setXAxisBoundsManual(true);
        graph.getViewport().setMinX(0);
        graph.getViewport().setMaxX(coinsOverTime.size());

        if (coins >= 0 && coins < 101)
        {
            Button getCoinButton = addButton("Get 1 coin");
            getCoinButton.setId(R.id.one);
            getCoinButton.setOnClickListener(new View.OnClickListener() {
                public void onClick(View v) {
                    getOneCoin(v);
                }
            });
        }

        if (coins >= 11 && coins < 501)
        {
            Button getCoinButton = addButton("Get 10 coins");
            getCoinButton.setId(R.id.ten);
            getCoinButton.setOnClickListener(new View.OnClickListener() {
                public void onClick(View v) {
                    getTenCoins(v);
                }
            });
        }

        if (coins >= 21 && coins < 2001)
        {
            Button getCoinButton = addButton("Get 20 coins");
            getCoinButton.setId(R.id.twenty);
            getCoinButton.setOnClickListener(new View.OnClickListener() {
                public void onClick(View v) {
                    getTwentyCoins(v);
                }
            });
        }

        if (coins >= 101 && coins < 5001)
        {
            Button getCoinButton = addButton("Get 100 coins");
            getCoinButton.setId(R.id.one_hundred);
            getCoinButton.setOnClickListener(new View.OnClickListener() {
                public void onClick(View v) {
                    getOneHundredCoins(v);
                }
            });
        }

        if (coins >= 501 && coins < 10001)
        {
            Button getCoinButton = addButton("Get 500 coins");
            getCoinButton.setId(R.id.five_hundred);
            getCoinButton.setOnClickListener(new View.OnClickListener() {
                public void onClick(View v) {
                    getFiveHundredCoins(v);
                }
            });
        }

        if (coins >= 2001)
        {
            Button getCoinButton = addButton("Get 2,000 coins");
            getCoinButton.setId(R.id.two_thousand);
            getCoinButton.setOnClickListener(new View.OnClickListener() {
                public void onClick(View v) {
                    getTwoThousandCoins(v);
                }
            });
        }

        if (coins >= 5001)
        {
            Button getCoinButton = addButton("Get 5,000 coins");
            getCoinButton.setId(R.id.five_thousand);
            getCoinButton.setOnClickListener(new View.OnClickListener() {
                public void onClick(View v) {
                    getFiveThousandCoins(v);
                }
            });
        }

        if (coins >= 10001)
        {
            Button getCoinButton = addButton("Get 10,000 coins");
            getCoinButton.setId(R.id.ten_thousand);
            getCoinButton.setOnClickListener(new View.OnClickListener() {
                public void onClick(View v) {
                    getTenThousandCoins(v);
                }
            });
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.action_items, menu);
        return true;
    }

    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.rules:
                // User chose the "Settings" item, show the app settings UI...
                return true;

            case R.id.action_settings:
                // User chose the "Favorite" action, mark the current item
                // as a favorite...
                return true;

            case android.R.id.home:
                return true;

            default:
                // If we got here, the user's action was not recognized.
                // Invoke the superclass to handle it.
                return super.onOptionsItemSelected(item);
        }
    }




    public void getOneCoin(View view){
        Intent intent = new Intent(this, gamble.class);
        Bundle bundle = new Bundle();
        bundle.putIntegerArrayList("COIN_HISTORY", coinsOverTime);
        intent.putExtra("GAMBLE", 1);
        intent.putExtra("COINS", coins);
        intent.putExtras(bundle);
        startActivity(intent);
    }

    public void getTenCoins(View view){
        Intent intent = new Intent(this, gamble.class);
        Bundle bundle = new Bundle();
        bundle.putIntegerArrayList("COIN_HISTORY", coinsOverTime);
        intent.putExtra("GAMBLE", 10);
        intent.putExtra("COINS", coins);
        intent.putExtras(bundle);
        startActivity(intent);
    }

    public void getTwentyCoins(View view){
        Intent intent = new Intent(this, gamble.class);
        Bundle bundle = new Bundle();
        bundle.putIntegerArrayList("COIN_HISTORY", coinsOverTime);
        intent.putExtra("GAMBLE", 20);
        intent.putExtra("COINS", coins);
        intent.putExtras(bundle);
        startActivity(intent);
    }

    public void getOneHundredCoins(View view){
        Intent intent = new Intent(this, gamble.class);
        Bundle bundle = new Bundle();
        bundle.putIntegerArrayList("COIN_HISTORY", coinsOverTime);
        intent.putExtra("GAMBLE", 100);
        intent.putExtra("COINS", coins);
        intent.putExtras(bundle);
        startActivity(intent);
    }

    public void getFiveHundredCoins(View view){
        Intent intent = new Intent(this, gamble.class);
        Bundle bundle = new Bundle();
        bundle.putIntegerArrayList("COIN_HISTORY", coinsOverTime);
        intent.putExtra("GAMBLE", 500);
        intent.putExtra("COINS", coins);
        intent.putExtras(bundle);
        startActivity(intent);
    }

    public void getTwoThousandCoins(View view){
        Intent intent = new Intent(this, gamble.class);
        Bundle bundle = new Bundle();
        bundle.putIntegerArrayList("COIN_HISTORY", coinsOverTime);
        intent.putExtra("GAMBLE", 2000);
        intent.putExtra("COINS", coins);
        intent.putExtras(bundle);
        startActivity(intent);
    }

    public void getFiveThousandCoins(View view){
        Intent intent = new Intent(this, gamble.class);
        Bundle bundle = new Bundle();
        bundle.putIntegerArrayList("COIN_HISTORY", coinsOverTime);
        intent.putExtra("GAMBLE", 5000);
        intent.putExtra("COINS", coins);
        intent.putExtras(bundle);
        startActivity(intent);
    }

    public void getTenThousandCoins(View view){
        Intent intent = new Intent(this, gamble.class);
        Bundle bundle = new Bundle();
        bundle.putIntegerArrayList("COIN_HISTORY", coinsOverTime);
        intent.putExtra("GAMBLE", 10000);
        intent.putExtra("COINS", coins);
        intent.putExtras(bundle);
        startActivity(intent);
    }

    public Button addButton(String name)
    {
        LinearLayout linearLayout = (LinearLayout) findViewById(R.id.linearLayout);
        Button newCoinButton = new Button(this);
        newCoinButton.setText(name);
        newCoinButton.setTextSize(30);
        //newCoinButton.setBackgroundColor(buttonColor);
        newCoinButton.setTextColor(textColor);
        //newCoinButton.setLayoutParams(new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT));
        linearLayout.addView(newCoinButton);

        return newCoinButton;
    }

    public DataPoint[] generateData()
    {
        int size = coinsOverTime.size();
        DataPoint[] values = new DataPoint[size];
        for (int i=0; i<size; i++)
        {
            int y1 = coinsOverTime.get(i);
            DataPoint v = new DataPoint(i, y1);
            values[i] = v;
        }

        return values;
    }
}

这是它所涉及的 Gamble Activity ...

package com.example.getcoins;

import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.ActionBar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.View;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.Collections;

public class gamble extends AppCompatActivity {

    ArrayList<Integer> buttonValues = getButtonValues();
    //ArrayList<Integer> coinHistory = getCoinHistory();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_gamble);
        Toolbar myToolbar = (Toolbar) findViewById(R.id.my_toolbar);
        setSupportActionBar(myToolbar);
        ActionBar ab = getSupportActionBar();
        ab.setDisplayHomeAsUpEnabled(false);

        TextView textViewLeft = (TextView) findViewById(R.id.textView2);
        TextView textViewRight = (TextView) findViewById(R.id.textView3);
        TextView textViewCoins = (TextView) findViewById(R.id.textView4);

        textViewCoins.setText("Good Luck!");


        if (buttonValues.get(0) == 0)
        {
            textViewLeft.setText("Winner");
        }

        else
        {
            textViewLeft.setText("Loser");
        }

        if (buttonValues.get(1) == 0)
        {
            textViewRight.setText("Winner");
        }

        else
        {
            textViewRight.setText("Loser");
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.action_items, menu);
        return true;
    }

    public ArrayList<Integer> getButtonValues()
    {
        ArrayList<Integer> buttonvalues = new ArrayList<Integer>();
        buttonvalues.add(0);
        buttonvalues.add(1);
        Collections.shuffle(buttonvalues);
        return buttonvalues;
    }

    public void leftButtonClick(View view)
    {
        if (buttonValues.get(0) == 0)
        {
           winner();
        }

        else
        {
            loser();
        }
    }

    public void rightButtonClick(View view)
    {
        if (buttonValues.get(1) == 0)
        {
            winner();
        }

        else
        {
            loser();
        }
    }

    public void winner()
    {
        Intent oldintent = getIntent();
        Bundle oldbundle = oldintent.getExtras();
        int gambleamount = oldintent.getIntExtra("GAMBLE", 1);
        int coins = oldintent.getIntExtra("COINS", 1);
        ArrayList<Integer> coinHistory = oldbundle.getIntegerArrayList("COIN_HISTORY");

        Intent intent = new Intent(this, MainActivity.class);
        Bundle bundle = new Bundle();
        bundle.putIntegerArrayList("COIN_HISTORY", coinHistory);
        intent.putExtra("WINNER", true);
        intent.putExtra("GAMBLE", gambleamount);
        intent.putExtra("COINS", coins);
        intent.putExtras(bundle);
        startActivity(intent);
    }

    public void loser()
    {
        Intent oldintent = getIntent();
        Bundle oldbundle = oldintent.getExtras();
        int gambleamount = oldintent.getIntExtra("GAMBLE", 1);
        int coins = oldintent.getIntExtra("COINS", 1);
        ArrayList<Integer> coinHistory = oldbundle.getIntegerArrayList("COIN_HISTORY");

        Intent intent = new Intent(this, MainActivity.class);
        Bundle bundle = new Bundle();
        bundle.putIntegerArrayList("COIN_HISTORY", coinHistory);
        intent.putExtra("WINNER", false);
        intent.putExtra("GAMBLE", gambleamount);
        intent.putExtra("COINS", coins);
        intent.putExtras(bundle);
        startActivity(intent);
    }
}

我感谢任何人能够提供的任何帮助。

卢克

更新:这是我的 logcat...或者至少我认为是相关部分。崩溃发生后，我捕获了它给我的文字。

04-06 16:10:39.091 3897-3897/? I/art: Late-enabling -Xcheck:jni
04-06 16:10:39.322 3897-3897/com.example.getcoins W/System: ClassLoader referenced unknown path: /data/app/com.example.getcoins-1/lib/arm64
04-06 16:10:39.363 3897-3897/com.example.getcoins I/InstantRun: Starting Instant Run Server for com.example.getcoins
04-06 16:10:42.158 3897-3897/com.example.getcoins W/art: Before Android 4.1, method android.graphics.PorterDuffColorFilter android.support.graphics.drawable.VectorDrawableCompat.updateTintFilter(android.graphics.PorterDuffColorFilter, android.content.res.ColorStateList, android.graphics.PorterDuff$Mode) would have incorrectly overridden the package-private method in android.graphics.drawable.Drawable
04-06 16:10:42.643 3897-3897/com.example.getcoins D/AndroidRuntime: Shutting down VM
04-06 16:10:42.645 3897-3897/com.example.getcoins E/AndroidRuntime: FATAL EXCEPTION: main
                                                                    Process: com.example.getcoins, PID: 3897
                                                                    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.getcoins/com.example.getcoins.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.util.ArrayList.add(java.lang.Object)' on a null object reference
                                                                        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2671)
                                                                        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2736)
                                                                        at android.app.ActivityThread.-wrap12(ActivityThread.java)
                                                                        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1478)
                                                                        at android.os.Handler.dispatchMessage(Handler.java:102)
                                                                        at android.os.Looper.loop(Looper.java:154)
                                                                        at android.app.ActivityThread.main(ActivityThread.java:6154)
                                                                        at java.lang.reflect.Method.invoke(Native Method)
                                                                        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867)
                                                                        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:757)
                                                                     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.util.ArrayList.add(java.lang.Object)' on a null object reference
                                                                        at com.example.getcoins.MainActivity.onCreate(MainActivity.java:50)
                                                                        at android.app.Activity.performCreate(Activity.java:6683)
                                                                        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1140)
                                                                        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2624)
                                                                        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2736) 
                                                                        at android.app.ActivityThread.-wrap12(ActivityThread.java) 
                                                                        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1478) 
                                                                        at android.os.Handler.dispatchMessage(Handler.java:102) 
                                                                        at android.os.Looper.loop(Looper.java:154) 
                                                                        at android.app.ActivityThread.main(ActivityThread.java:6154) 
                                                                        at java.lang.reflect.Method.invoke(Native Method) 
                                                                        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867) 
                                                                        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:757) 

更新:

首先感谢您的回复!这对我来说非常有教育意义!我想按照我目前的逻辑来判断我认为正在发生的事情，看看我是否走在正确的轨道上。似乎当应用程序第一次编译到我的手机上时，一切都很好(即主 Activity 中的全局变量可以正确看到并处理)。

但是，在查看 Pavel B. 建议我查看的链接后，似乎通过这个过程... A simplified illustration of the activity lifecycle.

...一旦我杀死应用程序并重新打开它，它就会直接进入 onCreate() 方法(并且似乎跳过了上面定义的全局变量)。这是怎么回事？

我已对我认为有帮助的评论进行了投票，但它表示由于我的声誉低于 15，因此不会公开。

再次非常感谢您!!

卢克

Answer 1

这可能会也可能不会解决您的问题，但是当您从主要 Activity 中调用“赌博” Activity 时，您应该使用 startActivityForResult() 并注册回调接收器来处理结果...

即您当前正在“启动”主要 Activity 本身，而不是仅通过 setResult 将结果传递回它

参见:

https://developer.android.com/training/basics/intents/result.html

和

https://developer.android.com/reference/android/os/ResultReceiver.html

更新:

考虑创建一个您可以使用的静态最终请求代码:

public static final int REQUEST_CODE_GAMBLE = 172;

使用静态请求代码将 getCoin 方法更改为 startActivityForResult():

public void getOneCoin(View view){
    Intent intent = new Intent(this, gamble.class);
    Bundle bundle = new Bundle();
    bundle.putIntegerArrayList("COIN_HISTORY", coinsOverTime);
    intent.putExtra("GAMBLE", 1);
    intent.putExtra("COINS", coins);
    intent.putExtras(bundle);
    startActivityForResult(intent, REQUEST_CODE_GAMBLE);
}

然后在 MainActivity 中重写 onActivityResult():

@Override
protected void onActivityResult(final int requestCode, final int resultCode, final Intent intent){
super.onActivityResult(requestCode, resultCode, intent);
    if(requestCode == REQUEST_CODE_GAMBLE){
        if(resultCode == RESULT_OK){

            //do all that same stuff you were doing in onCreate() in your MainActivity
            //i.e. :
            coins = intent.getIntExtra("COINS", 1);
            //etc

        }
    }


}

然后在赌博 Activity 中的 Winner() 和 Loser() 方法中，只需设置结果并调用 finish():

public void winner()
{
    Intent oldintent = getIntent();
    Bundle oldbundle = oldintent.getExtras();
    int gambleamount = oldintent.getIntExtra("GAMBLE", 1);
    int coins = oldintent.getIntExtra("COINS", 1);
    ArrayList<Integer> coinHistory = oldbundle.getIntegerArrayList("COIN_HISTORY");
    Intent intent = new Intent();
    Bundle bundle = new Bundle();
    bundle.putIntegerArrayList("COIN_HISTORY", coinHistory);
    intent.putExtra("WINNER", true);
    intent.putExtra("GAMBLE", gambleamount);
    intent.putExtra("COINS", coins);
    intent.putExtras(bundle);
    getParent().setResult(Activity.RESULT_OK, intent);
    finish();
}

当您的赌博 Activity “完成”时，它会将所有 Intent 数据发送到 MainActivity 的新 onActivityResult() 方法，您可以用它做您想做的事情