Java Can'；是否无法在其他视图中访问ArrayList？android空指针异常

我试图访问在上一个视图中设置的上一个类的整数数组列表，但是当我转到新视图时，它似乎没有正确保存数组列表。我认为它删除了其中的任何内容

是否仍然可以访问已设置的“lightInfo”

连接测试声明

public class ConnectTest extends MainActivity {
    TextView out;
    private static final int REQUEST_ENABLE_BT = 1;
    private BluetoothAdapter btAdapter = null;
    private BluetoothSocket btSocket = null;
    private OutputStream outStream = null;

    // Well known SPP UUID
    private static final UUID MY_UUID =
            UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");

    // Insert your server's MAC address
    private static String address = "A4:5E:60:EB:3C:E8";
    ArrayList<Integer> temp = ((MainActivity) getApplicationContext()).lightInfo;

public class MainActivity extends AppCompatActivity {


    private final static int REQUEST_ENABLE_BT = 1;
    UUID myUUID = UUID.randomUUID();
    private static final int DISCOVER_DURATION = 300;
    private static final int REQUEST_BLU = 1;
    ArrayAdapter<String> mArrayAdapter;
    ArrayList<Double> currentBodyTemp;
    BluetoothAdapter mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
    boolean targetTimeZoneIsAhead = false;
    boolean targetTimeZoneIsBehind = false;

    int currentWakeTime = 420;
    int currentSleepTime = 1320;

    int targetWakeTime = 0;
    int targetSleepTime = 0;
    int daysLeft = 0;
    int timeDifference = 0;

    public ArrayList<Integer> lightInfo;

public类ConnectTest扩展main活动{
文本视图输出；
私有静态最终整数请求_ENABLE_BT=1；
私有蓝牙适配器btAdapter=null；
私有BluetoothSocket btSocket=null；
私有OutputStream outStream=null；
//众所周知的SPP UUID
私有静态最终UUID MY_UUID=
UUID.来自字符串（“00001101-0000-1000-8000-00805F9B34FB”）；
//插入服务器的MAC地址
私有静态字符串地址=“A4:5E:60:EB:3C:E8”；
ArrayList temp=（（MainActivity）getApplicationContext（））.lightInfo；

调用创建错误的temp：

 String finalMessage = "";
        for (int i = 0; i < temp.size(); i++) {
            finalMessage = finalMessage + temp.get(i) + "\n";
        }

        String message = finalMessage;

String finalMessage=“”；
对于（int i=0；i

主要活动声明

public class ConnectTest extends MainActivity {
    TextView out;
    private static final int REQUEST_ENABLE_BT = 1;
    private BluetoothAdapter btAdapter = null;
    private BluetoothSocket btSocket = null;
    private OutputStream outStream = null;

    // Well known SPP UUID
    private static final UUID MY_UUID =
            UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");

    // Insert your server's MAC address
    private static String address = "A4:5E:60:EB:3C:E8";
    ArrayList<Integer> temp = ((MainActivity) getApplicationContext()).lightInfo;

public class MainActivity extends AppCompatActivity {


    private final static int REQUEST_ENABLE_BT = 1;
    UUID myUUID = UUID.randomUUID();
    private static final int DISCOVER_DURATION = 300;
    private static final int REQUEST_BLU = 1;
    ArrayAdapter<String> mArrayAdapter;
    ArrayList<Double> currentBodyTemp;
    BluetoothAdapter mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
    boolean targetTimeZoneIsAhead = false;
    boolean targetTimeZoneIsBehind = false;

    int currentWakeTime = 420;
    int currentSleepTime = 1320;

    int targetWakeTime = 0;
    int targetSleepTime = 0;
    int daysLeft = 0;
    int timeDifference = 0;

    public ArrayList<Integer> lightInfo;

public类MainActivity扩展了AppCompatActivity{
私有最终静态整数请求\启用\ BT=1；
UUID myUUID=UUID.randomUUID（）；
专用静态最终int DISCOVER_持续时间=300；
私有静态最终整数请求_BLU=1；
ArrayAdapter mArrayAdapter；
ArrayList currentBodyTemp；
BluetoothAdapter mBluetoothAdapter=BluetoothAdapter.getDefaultAdapter（）；
布尔值targetTimeZoneIsAhead=false；
布尔targetTimeZoneIsBehind=false；
int currentWakeTime=420；
int currentSleepTime=1320；
int targetWakeTime=0；
int targetSleepTime=0；
int daysLeft=0；
int时差=0；
公共ArrayList lightInfo；

错误消息：

10-27 12:59:56.141 15803-15803/com.teamfara.circadianrhythmmonitor4 D/AndroidRuntime: Shutting down VM
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime: FATAL EXCEPTION: main
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime: Process: com.teamfara.circadianrhythmmonitor4, PID: 15803
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime: java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.teamfara.circadianrhythmmonitor4/com.teamfara.circadianrhythmmonitor4.ConnectTest}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.Context android.content.Context.getApplicationContext()' on a null object reference
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime:     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2964)
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime:     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3218)
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime:     at android.app.ActivityThread.access$1000(ActivityThread.java:198)
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime:     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1676)
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime:     at android.os.Handler.dispatchMessage(Handler.java:102)
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime:     at android.os.Looper.loop(Looper.java:145)
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime:     at android.app.ActivityThread.main(ActivityThread.java:6837)
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime:     at java.lang.reflect.Method.invoke(Native Method)
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime:     at java.lang.reflect.Method.invoke(Method.java:372)
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1404)
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1199)
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime:  Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.Context android.content.Context.getApplicationContext()' on a null object reference
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime:     at android.content.ContextWrapper.getApplicationContext(ContextWrapper.java:111)
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime:     at com.teamfara.circadianrhythmmonitor4.ConnectTest.<init>(ConnectTest.java:34)
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime:     at java.lang.reflect.Constructor.newInstance(Native Method)
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime:     at java.lang.Class.newInstance(Class.java:1684)
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime:     at android.app.Instrumentation.newActivity(Instrumentation.java:1080)
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime:     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2954)
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime:     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3218) 
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime:     at android.app.ActivityThread.access$1000(ActivityThread.java:198) 
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime:     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1676) 
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime:     at android.os.Handler.dispatchMessage(Handler.java:102) 
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime:     at android.os.Looper.loop(Looper.java:145) 
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime:     at android.app.ActivityThread.main(ActivityThread.java:6837) 
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime:     at java.lang.reflect.Method.invoke(Native Method) 
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime:     at java.lang.reflect.Method.invoke(Method.java:372) 
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1404) 
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1199) 

10-27 12:59:56.141 15803-15803/com.teamfara.bircadianrhythmmonitor4 D/AndroidRuntime:关闭虚拟机
10-27 12:59:56.151 15803-15803/com.teamfara.bircadianrhythmmonitor4 E/AndroidRuntime:致命异常：main
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime:Process:com.teamfara.circadianrhythmmonitor4，PID:15803
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime:java.lang.RuntimeException:无法实例化活动组件信息{com.teamfara.circadianrhythmmonitor4/com.teamfara.circadianrhythmmonitor4.ConnectTest}：java.lang.NullPointerException:尝试在空对象引用上调用虚拟方法“android.content.Context android.content.getApplicationContext（）”
10-27 12:59:56.151 15803-15803/com.teamfara.bircadiarinrhythmmonitor4 E/AndroidRuntime:at android.app.ActivityThread.performLaunchActivity（ActivityThread.java:2964）
10-27 12:59:56.151 15803-15803/com.teamfara.bircadiarinrhythmmonitor4 E/AndroidRuntime:at android.app.ActivityThread.handleLaunchActivity（ActivityThread.java:3218）
10-27 12:59:56.151 15803-15803/com.teamfara.circadiarinrhythmmonitor4 E/AndroidRuntime:android.app.ActivityThread.access$1000（ActivityThread.java:198）
10-27 12:59:56.151 15803-15803/com.teamfara.bircadiarinrhythmmonitor4 E/AndroidRuntime:android.app.ActivityThread$H.handleMessage（ActivityThread.java:1676）
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime:at android.os.Handler.dispatchMessage（Handler.java:102）
10-27 12:59:56.151 15803-15803/com.teamfara.circadiarinrhythmmonitor4 E/AndroidRuntime:at android.os.Looper.loop（Looper.java:145）
10-27 12:59:56.151 15803-15803/com.teamfara.circadiarinrhythmmonitor4 E/AndroidRuntime:android.app.ActivityThread.main（ActivityThread.java:6837）
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime:at java.lang.reflect.Method.invoke（本机方法）
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime:at java.lang.reflect.Method.invoke（Method.java:372）
10-27 12:59:56.151 15803-15803/com.teamfara.昼夜节律监视器4 E/AndroidRuntime:com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run（ZygoteInit.java:1404）
10-27 12:59:56.151 15803-15803/com.teamfara.circadiarinrhythmmonitor4 E/AndroidRuntime:com.android.internal.os.ZygoteInit.main（ZygoteInit.java:1199）
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime:原因：java.lang.NullPointerException:尝试对空对象引用调用虚拟方法“android.content.Context android.content.Context.getApplicationContext（）”
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime:at android.content.ContextWrapper.getApplicationContext（ContextWrapper.java:111）
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime:com.teamfara.circadianrhythmmonitor4.ConnectTest.（ConnectTest.java:34）
10-27 12:59:56.151 15803-15803/com.teamfara.circadianrhythmmonitor4 E/AndroidRuntime:at java.lang.reflect.Constructor.newInstance（本机方法）
10-27 12:59:56.151 15803-15803/com.teamfara.昼夜节律监视器4 E/AndroidRuntime:at java.lang.Class.newInstance（Class.java:1684）
10-27 12:59:56.151 15803-15803/com.teamfara.circadiarinrhythmmonitor4 E/AndroidRuntime:at android.app.Instrumentation.newActivity（Instrumentation.java:1080）
10-27 12:59:56.151 15803-15803/com.teamfara.bircadiarinrhythmmonitor4 E/AndroidRuntime:at android.app.ActivityThread.performLaunchActivity（ActivityThread.java:2954）
10-27 12:59:56.151 15803-15803/com.teamfara.bircadiarinrhythmmonitor4 E/AndroidRuntime:at android.app.ActivityThread.handleLaunchActivity（ActivityThread.java:3218）
10-27 12:59:56.151 15803-15803/com.teamfara.circadiarinrhythmmonitor4 E/AndroidRuntime:android.app.ActivityThread.access$1000（ActivityThread.java:198）
10-27 12:59:56.1