java - 非常奇怪的 Android NullPointerException

<分区>

我一直致力于用从我的 sqlite 数据库中检索到的数据填充 ListView，我的数据库文件 DBMainAdapter 中的代码完美运行( fragment 以节省空间)我知道这一点，因为当我在一个单独的 Activity 中调用我的 getAll() 时，我正在使用(不是包括)我得到了我的 ArrayList 并且我可以很好地使用它打印出里面的内容但是我注意到每当我尝试在我的 ProfileListActivity 中做同样的事情时> 我不断收到 NullPointerException 抛出。我做错了什么？!

错误日志:

04-21 06:42:31.669: W/dalvikvm(6107): threadid=1: thread exiting with uncaught exception (group=0xb3a8db90)
04-21 06:42:31.749: E/AndroidRuntime(6107): FATAL EXCEPTION: main
04-21 06:42:31.749: E/AndroidRuntime(6107): Process: com.test.profilekeeper, PID: 6107
04-21 06:42:31.749: E/AndroidRuntime(6107): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.test.profilekeeper/com.test.profilekeeper.ProfileListActivity}: java.lang.NullPointerException
04-21 06:42:31.749: E/AndroidRuntime(6107):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2176)
04-21 06:42:31.749: E/AndroidRuntime(6107):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2226)
04-21 06:42:31.749: E/AndroidRuntime(6107):     at android.app.ActivityThread.access$700(ActivityThread.java:135)
04-21 06:42:31.749: E/AndroidRuntime(6107):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1397)
04-21 06:42:31.749: E/AndroidRuntime(6107):     at android.os.Handler.dispatchMessage(Handler.java:102)
04-21 06:42:31.749: E/AndroidRuntime(6107):     at android.os.Looper.loop(Looper.java:137)
04-21 06:42:31.749: E/AndroidRuntime(6107):     at android.app.ActivityThread.main(ActivityThread.java:4998)
04-21 06:42:31.749: E/AndroidRuntime(6107):     at java.lang.reflect.Method.invokeNative(Native Method)
04-21 06:42:31.749: E/AndroidRuntime(6107):     at java.lang.reflect.Method.invoke(Method.java:515)
04-21 06:42:31.749: E/AndroidRuntime(6107):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:777)
04-21 06:42:31.749: E/AndroidRuntime(6107):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:593)
04-21 06:42:31.749: E/AndroidRuntime(6107):     at dalvik.system.NativeStart.main(Native Method)
04-21 06:42:31.749: E/AndroidRuntime(6107): Caused by: java.lang.NullPointerException
04-21 06:42:31.749: E/AndroidRuntime(6107):     at com.test.profilekeeper.LoadedData.<init>(LoadedData.java:17)
04-21 06:42:31.749: E/AndroidRuntime(6107):     at com.test.profilekeeper.ProfileListActivity.onCreate(ProfileListActivity.java:23)
04-21 06:42:31.749: E/AndroidRuntime(6107):     at android.app.Activity.performCreate(Activity.java:5243)
04-21 06:42:31.749: E/AndroidRuntime(6107):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
04-21 06:42:31.749: E/AndroidRuntime(6107):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2140)
04-21 06:42:31.749: E/AndroidRuntime(6107):     ... 11 more

在 com.test.profilekeeper.LoadedData.(LoadedData.java:17) 的位置:ArrayList listdata = dbhelper.getAll();//构造函数

在 com.test.profilekeeper.ProfileListActivity.onCreate(ProfileListActivity.java:23) 的位置:LoadedData mydata = new LoadedData();

public class DBMainAdapter{
    DBMain dbhelper;

    public DBMainAdapter(Context context){
        dbhelper = new DBMain(context);
    }

    public long insertprofiledata(String fname, String lname, String age, String gender, String username, String password){
        SQLiteDatabase db = dbhelper.getWritableDatabase();
        ContentValues cv = new ContentValues();

        cv.put(DBMain.FIRSTNAME, fname);
        cv.put(DBMain.LASTNAME, lname);
        cv.put(DBMain.AGE, age);
        cv.put(DBMain.GENDER, gender);
        cv.put(DBMain.USERNAME, username);
        cv.put(DBMain.PASSWORD, password);

        long id = db.insert(DBMain.TABLE_NAME, null, cv);
        return id;
    }

    public ArrayList<String[]> getAll(){
        SQLiteDatabase db = dbhelper.getWritableDatabase();
        String[] columns = {DBMain.UID, DBMain.FIRSTNAME, DBMain.LASTNAME, DBMain.AGE, DBMain.GENDER};
        Cursor curs = db.query(DBMain.TABLE_NAME, columns, null, null, null, null, null);

        int index1 = curs.getColumnIndex(DBMain.UID);
        int index2 = curs.getColumnIndex(DBMain.FIRSTNAME);
        int index3 = curs.getColumnIndex(DBMain.LASTNAME);
        int index4 = curs.getColumnIndex(DBMain.AGE);
        int index5 = curs.getColumnIndex(DBMain.GENDER);

        StringBuffer buffer = new StringBuffer();

        while(curs.moveToNext()){
            String uid = curs.getString(index1);
            String fname = curs.getString(index2);
            String lname = curs.getString(index3);
            String age = curs.getString(index4);
            String gender = curs.getString(index5);

            buffer.append(uid+","+fname+","+lname+","+age+","+gender+" ");
        }

        String[] row = buffer.toString().split(" ");
        String profilebuilder[][] = new String[row.length][row[0].length()];

        for(int i = 0; i < row.length; i++){
            String[] profile = row[i].split(",");
            for(int j = 0; j < profile.length; j++){
                profilebuilder[i][j] = profile[j];
            }
        }

        String[] ids = new String[profilebuilder.length];
        String[] firstname = new String[profilebuilder.length];
        String[] ages = new String[profilebuilder.length];
        String[] genders = new String[profilebuilder.length];

        for(int k = 0; k < profilebuilder.length; k++){
            for(int l = 0; l < profilebuilder[0].length; l++){
                ids[k] = profilebuilder[k][0];
                firstname[k] = profilebuilder[k][1];
                ages[k] = profilebuilder[k][3];
                genders[k] = profilebuilder[k][4];
            }
        }

        ArrayList<String[]> alldata = new ArrayList<String[]>();
        alldata.add(ids);
        alldata.add(firstname);
        alldata.add(ages);
        alldata.add(genders);       

        return alldata;
    }
}

    public class LoadedData {
        DBMainAdapter dbhelper;

        String[] ids;
        String[] firstnames;
        String[] ages;
        String[] genders;

        public LoadedData(){
            ArrayList<String[]> listdata = dbhelper.getAll();

            ids =  new String[listdata.get(0).length];
            firstnames = new String[listdata.get(0).length];
            ages = new String[listdata.get(0).length];
            genders  = new String[listdata.get(0).length];

            ids = listdata.get(0);
            firstnames = listdata.get(1);
            ages = listdata.get(2);
            genders = listdata.get(3);
        }

        public String[] getIds() {
            return ids;
        }

        public String[] getFirstnames() {
            return firstnames;
        }

        public String[] getAges() {
            return ages;
        }

        public String[] getGenders() {
            return genders;
        }
    }


public class ProfileListActivity extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        LoadedData mydata = new LoadedData();
        populateListView(mydata);   
    }

    private void populateListView(LoadedData mydata) {
        ArrayAdapter<LoadedData> adapter = new MyListAdapter(mydata);
        ListView list = (ListView) findViewById(R.id.listView);
        list.setAdapter(adapter);
    }

    private class MyListAdapter extends ArrayAdapter<LoadedData>{
        LoadedData mdata;
        public MyListAdapter(LoadedData data){
            super(ProfileListActivity.this, R.layout.row);
            this.mdata = data;
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            View itemView = convertView;
            if(itemView == null){
                itemView = getLayoutInflater().inflate(R.layout.row, parent, false);
            }

            TextView first_name = (TextView) itemView.findViewById(R.id.nameListTextView);
            TextView id = (TextView) itemView.findViewById(R.id.idListTextView);
            TextView age = (TextView) itemView.findViewById(R.id.ageListTextView);
            ImageView img = (ImageView) itemView.findViewById(R.id.imageViewList);

            id.setText(mdata.getIds()[position]);
            first_name.setText(mdata.getFirstnames()[position]);
            age.setText(mdata.getAges()[position]);

            if(mdata.getGenders()[position].equalsIgnoreCase("Male")){
                img.setImageResource(R.raw.man_thumb);
            }else{
                img.setImageResource(R.raw.woman_thumb);
            }   

            return itemView;
        }
    }
}

java - 非常奇怪的 Android NullPointerException

上一篇：java - 使用对象数组获取 NullPointerException

下一篇：java - spring amqp rabbitmq MessageListener 不工作