當我將數據從活動傳遞到活動時，獲取 Null 指針 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
    }]

這是我如何處理選項

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

但我收到此錯誤：

java.lang.NullPointerException: Attempt to invoke interface method 'int java.util.List.size()' on a null object reference at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3507) at android.app.ActivityThread. handleLaunchActivity(ActivityThread.java:3661) at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83) at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:140) at android.app.servertransaction.TransactionExecutor .execute(TransactionExecutor.java:100) 在 android.app .ActivityThread$H.handleMessage(ActivityThread.java:2232) at android.os.Handler.dispatchMessage(Handler.java:107) at android.os.Looper.loop(Looper.java:238) at android.app.ActivityThread. main(ActivityThread.java:7824) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492) at com.android.internal. os.ZygoteInit.main(ZygoteInit.java:981) Caused by: java.lang.NullPointerException: Attempt to invoke interface method 'int java.util.List.size()' on a Z37A6 259CC0C1DAE299A7866489DFF0BDZ object 參考

你能幫我解決這個問題嗎

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

通過這種方式，我正在處理問題清單。 我能夠閱讀問題。 但我無法閱讀答案。 你能幫我嗎

Answer 1

從第一次活動使用

intent.putParcelableArrayListExtra("questionsData", questionsArrayList);

在第二次活動中使用

questionsList = intent.getParcelableArrayListExtra("questionsData");