InputStream 返回 NullPointerException (Java) [英] InputStream returning NullPointerException (Java)

问题描述

这是获取 NullPointerException 错误的代码:

Here is the code that is getting the NullPointerException error:

InputStream is = getAssets().open("twentyone.txt");
InputStreamReader iz=new InputStreamReader(is);
BufferedReader br = new BufferedReader(iz);

可能出了什么问题?

*printStackTrace

* the printStackTrace

03-19 18:20:18.662: E/AndroidRuntime(929): Caused by: java.lang.NullPointerException

编辑 2:代码直到异常:

Edit 2: Code till the exception:

public class ListViewAa3 extends ListViewA{



public String[] process(String cti)throws IOException{
    String ctid=cti;
    Log.d("Outside try invoked","tag1");
    try{
        Log.d("beginning of try invoked","tag2");
        try{
    InputStream is = getAssets().open("USCOUNTIES.txt");
    InputStreamReader iz=new InputStreamReader(is);
    BufferedReader br = new BufferedReader(iz);}catch(Exception e){e.printStackTrace();}

推荐答案

好的，我明白了.我必须将主要活动的上下文传递给这个类，然后使用 context.getAssets.open("twentyone.txt");

OK, I got it. I had to pass the context of the main activity to this class, then use context.getAssets.open("twentyone.txt");

对于有同样问题的任何人，请执行以下操作:将其放在具有活动的类的 onCreate 函数中:Context context=getApplicationContext();

To anyone who has the same problem, do this: Put this in the onCreate function of the class with activity: Context context=getApplicationContext();

将上下文传递给新类的函数(在我的例子中是process(String a,Context context)")然后在进程函数中输入:

Pass context to the new class's function(in my case "process(String a,Context context)") Then type this in the process function:

InputStream is = context.getAssets().open("twentyone.txt");

我花了 4 个小时才弄清楚这么愚蠢的事情.

Took me 4 hours to figure such a silly thing out.

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