Question

我已经尝试了所有形式的错误检查，以便捕获并处理错误检查，但没有任何作用，它一直在崩溃。

Cursor cursor = null;
    try{
     cursor  = mydb.getAllRows();
    }finally{
        if(cursor == null)
        {
            // I want to exit here and do nothing. 
            // Crashes here. 

        }
        else{if(cursor.moveToFirst()){
             do{
                String id= cursor.getString(0);
                String text = cursor.getString(1);
                String cooktime = cursor.getString(2);
                String difficulty = cursor.getString(3);
                String making = cursor.getString(4);




                }while(cursor.moveToNext());
             }
          cursor.close();

        }

    }

我知道mydb中没有任何内容，所以如何对此问题进行错误检查，以免崩溃。

错误记录

12-03 14:54:21.259: E/AndroidRuntime(16766): FATAL EXCEPTION: main
12-03 14:54:21.259: E/AndroidRuntime(16766): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.exasmple.test/com.exasmple.test.List_of_recipes}: java.lang.NullPointerException
12-03 14:54:21.259: E/AndroidRuntime(16766):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2338)
12-03 14:54:21.259: E/AndroidRuntime(16766):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2388)
12-03 14:54:21.259: E/AndroidRuntime(16766):    at android.app.ActivityThread.access$900(ActivityThread.java:148)
12-03 14:54:21.259: E/AndroidRuntime(16766):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1319)
12-03 14:54:21.259: E/AndroidRuntime(16766):    at android.os.Handler.dispatchMessage(Handler.java:99)
12-03 14:54:21.259: E/AndroidRuntime(16766):    at android.os.Looper.loop(Looper.java:137)
12-03 14:54:21.259: E/AndroidRuntime(16766):    at android.app.ActivityThread.main(ActivityThread.java:5457)
12-03 14:54:21.259: E/AndroidRuntime(16766):    at java.lang.reflect.Method.invokeNative(Native Method)
12-03 14:54:21.259: E/AndroidRuntime(16766):    at java.lang.reflect.Method.invoke(Method.java:525)
12-03 14:54:21.259: E/AndroidRuntime(16766):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:854)
12-03 14:54:21.259: E/AndroidRuntime(16766):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:670)
12-03 14:54:21.259: E/AndroidRuntime(16766):    at dalvik.system.NativeStart.main(Native Method)
12-03 14:54:21.259: E/AndroidRuntime(16766): Caused by: java.lang.NullPointerException
12-03 14:54:21.259: E/AndroidRuntime(16766):    at com.exasmple.test.List_of_recipes.onCreate(List_of_recipes.java:114)
12-03 14:54:21.259: E/AndroidRuntime(16766):    at android.app.Activity.performCreate(Activity.java:5234)
12-03 14:54:21.259: E/AndroidRuntime(16766):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
12-03 14:54:21.259: E/AndroidRuntime(16766):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2302)
12-03 14:54:21.259: E/AndroidRuntime(16766):    ... 11 more

编辑：感谢大家的帮助，我使用了Nathan建议的try catch方法。

try{
        Cursor cursor  = mydb.getAllRows();

        // Do everything here

    }catch (NullPointerException e){
         // if caught then I do nothing and move on. 
    }

这阻止了我的问题，而不是尝试{}，最后是{}。在.getAllRows（）类调用中也发现了这个问题。

Android sqlite数据库getallRows（）检查null会出错

0 个答案: