Question

在我的应用程序中，我正在从sd card重新获取文件，并将其列在listview中。列出m得到异常致命的execption。我应该怎么做。请帮助我。我使用android2.2.same代码运行在2.3

下面是代码 -

 public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main); 
        //i=getIntent();
        File file = new File(Environment.getExternalStorageDirectory()
            + File.separator
            + "gallery" //folder name
        );
        if (!file.exists()) {
            file.mkdirs();
        }
        ListView lv = (ListView) findViewById(R.id.listview);
        list = getSD();
        lv.setAdapter((ListAdapter) new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, list));//here i'm getting exeception
        Log.d("LOG", "FIRE !!!! " );  

        lv.setOnItemClickListener(new OnItemClickListener() {
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                // When clicked, show a toast with the TextView text

                i=new Intent();
                i.putExtra("file","string");
                setResult(RESULT_OK, i);
                finish();
            }


        });
    }

异常 -

02-14 14:27:38.377: E/AndroidRuntime(395): FATAL EXCEPTION: main
02-14 14:27:38.377: E/AndroidRuntime(395): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.my.zproject/com.my.zproject.ImportFile}: java.lang.NullPointerException
02-14 14:27:38.377: E/AndroidRuntime(395):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
02-14 14:27:38.377: E/AndroidRuntime(395):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
02-14 14:27:38.377: E/AndroidRuntime(395):  at android.app.ActivityThread.access$2300(ActivityThread.java:125)
02-14 14:27:38.377: E/AndroidRuntime(395):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
02-14 14:27:38.377: E/AndroidRuntime(395):  at android.os.Handler.dispatchMessage(Handler.java:99)
02-14 14:27:38.377: E/AndroidRuntime(395):  at android.os.Looper.loop(Looper.java:123)
02-14 14:27:38.377: E/AndroidRuntime(395):  at android.app.ActivityThread.main(ActivityThread.java:4627)
02-14 14:27:38.377: E/AndroidRuntime(395):  at java.lang.reflect.Method.invokeNative(Native Method)
02-14 14:27:38.377: E/AndroidRuntime(395):  at java.lang.reflect.Method.invoke(Method.java:521)
02-14 14:27:38.377: E/AndroidRuntime(395):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
02-14 14:27:38.377: E/AndroidRuntime(395):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
02-14 14:27:38.377: E/AndroidRuntime(395):  at dalvik.system.NativeStart.main(Native Method)
02-14 14:27:38.377: E/AndroidRuntime(395): Caused by: java.lang.NullPointerException
02-14 14:27:38.377: E/AndroidRuntime(395):  at com.my.zproject.ImportFile.onCreate(ImportFile.java:38)
02-14 14:27:38.377: E/AndroidRuntime(395):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)

Answer 1

Caused by: java.lang.NullPointerException
02-14 14:27:38.377: E/AndroidRuntime(395):  at com.my.zproject.ImportFile.onCreate(ImportFile.java:38)

您的方法NullPointerException中的ImportFile课程中有一个onCreate(...) 38 。

Answer 2

问题是因为activity_main.xml。请检查文件名/变量名是否正确。

列出list view.getting exception中的项目

2 个答案: