当我从活动传递数据到活动时获得空指针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
}]

这是我如何处理选项

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

但是我得到这个错误:

. lang。NullPointerException:试图调用接口方法` int java.util.List.size() `处理空对象引用android.app.ActivityThread.performLaunchActivity (ActivityThread.java: 3507)android.app.ActivityThread.handleLaunchActivity (ActivityThread.java: 3661)android.app.servertransaction.LaunchActivityItem.execute (LaunchActivityItem.java: 83)android.app.servertransaction.TransactionExecutor.executeCallbacks (TransactionExecutor.java: 140)android.app.servertransaction.TransactionExecutor.execute (TransactionExecutor.java: 100)android.app.ActivityThread H.handleMessage美元(ActivityThread.java: 2232)android.os.Handler.dispatchMessage (Handler.java: 107)android.os.Looper.loop (Looper.java: 238)android.app.ActivityThread.main (ActivityThread.java: 7824)在java.lang.reflect.Method。调用(本地方法)com.android.internal.os.RuntimeInit MethodAndArgsCaller.run美元(RuntimeInit.java: 492)com.android.internal.os.ZygoteInit.main (ZygoteInit.java: 981)由于:java.lang.NullPointerException:试图在空对象上调用接口方法'int java.util.List.size()'参考

你能帮我一下吗?

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

用这种方式我正在处理问题列表。我能读出问题。但是我看不懂答案。你能帮我吗

Answer 1

From First Activity Use

intent.putParcelableArrayListExtra("questionsData", questionsArrayList);

在第二个活动中使用

questionsList = intent.getParcelableArrayListExtra("questionsData");