java在我将数据从一个活动传递到另一个活动时获取空指针Exp

Question

"questions": [
        {
            "number": 1,
            "text": "How many principles are there for plant distribution ?",
            "options": [
                {
                    "number": 1,
                    "text": "2",
                    "mark": 0
                },
                {
                    "number": 2,
                    "text": "4",
                    "mark": 0
                },
                {
                    "number": 3,
                    "text": "8",
                    "mark": 1
                },
                {
                    "number": 4,
                    "text": "16",
                    "mark": 0
                }
            ],
            "isMultiChoice": null
        },{
        "number": 1,
        "text": "How many principles are there for plant distribution ?",
        "options": [
            {
                "number": 1,
                "text": "2",
                "mark": 0
            },
            {
                "number": 2,
                "text": "4",
                "mark": 0
            },
            {
                "number": 3,
                "text": "8",
                "mark": 1
            },
            {
                "number": 4,
                "text": "16",
                "mark": 0
            }
        ],
        "isMultiChoice": null
    }]

以下是我处理选项的方式

optionsList = questionsList.get(question).getOptions();

但我有一个错误：

java.lang.NullPointerException: Attempt to invoke interface method 'int java.util.List.size()' on a null object reference at 安卓.app.ActivityThread.performLaunchActivity(ActivityThread.java:3507) at 安卓.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3661) at 安卓.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83) at 安卓.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:140) at 安卓.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:100) at 安卓.app.ActivityThread$H.handleMessage(ActivityThread.java:2232) at 安卓.os.Handler.dispatchMessage(Handler.java:107) at 安卓.os.Looper.loop(Looper.java:238) at 安卓.app.ActivityThread.main(ActivityThread.java:7824) at java.lang.reflect.Method.invoke(Native Method) at com.安卓.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492) at com.安卓.internal.os.ZygoteInit.main(ZygoteInit.java:981) Caused by: java.lang.NullPointerException: Attempt to invoke interface method 'int java.util.List.size()' on a null object reference

你能帮我吗

Intent intent = getIntent();
questionsList = intent.getParcelableArrayListExtra("questionsData");

通过这种方式，我正在处理问题列表。 我能阅读问题。但我看不懂答案。 你能帮我吗

Answer 1

从第一次活动开始使用

intent.putParcelableArrayListExtra("questionsData", questionsArrayList);

在第二个活动中使用

questionsList = intent.getParcelableArrayListExtra("questionsData");