Николай Семенов's questions

在 ...\app\src\main\res\raw 文件夹中有一个 test.json 文件：

{
  "qotd_date":"2021-07-22T00:00:00+00:00",
  "quote":
  {
    "id":63363,
    "dialogue":false,
    "private":false,
    "tags":[],
    "url":"https://favqs.com/quotes/meister-eckhart/63363-be-willing-to-",
    "favorites_count":1,
    "upvotes_count":0,
    "downvotes_count":0,
    "author":"Meister Eckhart",
    "author_permalink":"meister-eckhart",
    "body":"Be willing to be a begineer every single morning."
  }
}

为此我创建类：

import javax.annotation.Generated;
import com.google.gson.annotations.Expose;
import com.google.gson.annotations.SerializedName;

@Generated("jsonschema2pojo")
public class Example {

    @SerializedName("qotd_date")
    @Expose
    public String qotdDate;
    @SerializedName("quote")
    @Expose
    public Quote quote;

}

和

import java.util.List;
import javax.annotation.Generated;
import com.google.gson.annotations.Expose;
import com.google.gson.annotations.SerializedName;

@Generated("jsonschema2pojo")
public class Quote {

    @SerializedName("id")
    @Expose
    public Integer id;
    @SerializedName("dialogue")
    @Expose
    public Boolean dialogue;
    @SerializedName("private")
    @Expose
    public Boolean _private;
    @SerializedName("tags")
    @Expose
    public List<Object> tags = null;
    @SerializedName("url")
    @Expose
    public String url;
    @SerializedName("favorites_count")
    @Expose
    public Integer favoritesCount;
    @SerializedName("upvotes_count")
    @Expose
    public Integer upvotesCount;
    @SerializedName("downvotes_count")
    @Expose
    public Integer downvotesCount;
    @SerializedName("author")
    @Expose
    public String author;
    @SerializedName("author_permalink")
    @Expose
    public String authorPermalink;
    @SerializedName("body")
    @Expose
    public String body;
}

接下来，我开始使用 Gson：

import com.google.gson.Gson;

import java.io.FileReader;

public class GsonParser {

    public Example parser() {

        Gson gson = new Gson();

        try(FileReader reader = new FileReader("test.json")) {

            Example example = gson.fromJson(reader, Example.class);

            return example;
        } catch (Exception ex) {

        }
        return null;
    }
}

然后我尝试在 Log 中显示结果：

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.util.Log;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        GsonParser gsonParser = new GsonParser();
        Example example = gsonParser.parser();

        Log.d("log1",example.toString());

    }
}

但我明白NullPointerException 了 请告诉我如何解决它

我想在android开发中练习使用Retrofit，请指教几个开放api的网站。

当屏幕旋转时，有一些代码应该将旧的 AsyncTask 绑定到新的活动：

   public class MainActivity extends AppCompatActivity {
    
        MyTask mt;
        TextView tv;
    
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            Log.d("qwe", "create MainActivity: " + this.hashCode());
    
            tv = (TextView) findViewById(R.id.tv);
    
            mt = (MyTask) getLastNonConfigurationInstance();
            if (mt == null) {
                mt = new MyTask();
                mt.execute();
            }
            // передаем в MyTask ссылку на текущее MainActivity
            mt.link(this);
    
            Log.d("qwe", "create MyTask: " + mt.hashCode());
        }
    
        public Object onRetainNonConfigurationInstance() {
            // удаляем из MyTask ссылку на старое MainActivity
            mt.unLink();
            return mt;
        }
    
    
        static class MyTask extends AsyncTask<String, Integer, Void> {
    
            MainActivity activity;
    
            // получаем ссылку на MainActivity
            void link(MainActivity act) {
                activity = act;
            }
    
            // обнуляем ссылку
            void unLink() {
                activity = null;
            }
    
            @Override
            protected Void doInBackground(String... params) {
                try {
                    for (int i = 1; i <= 10; i++) {
                        TimeUnit.SECONDS.sleep(1);
                        publishProgress(i);
                        Log.d("qwe", "i = " + i + ", MyTask: " + this.hashCode()
                                + ", MainActivity: " + activity.hashCode());
                    }
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
    
                return null;
            }
    
            @Override
            protected void onProgressUpdate(Integer... values) {
                super.onProgressUpdate(values);
                activity.tv.setText("i = " + values[0]);
            }
        }
    }

问题是它public Object onRetainNonConfigurationInstance()带有红色下划线

启动时出现错误：

D:\User\GitHub\AsyncTaskLesson_6\app\src\main\java\com\semenov\asynctasklesson_6\MainActivity.java:35: error: onRetainNonConfigurationInstance() in MainActivity cannot override onRetainNonConfigurationInstance() in ComponentActivity
    public Object onRetainNonConfigurationInstance() {
                  ^
  overridden method is final

请告诉我该怎么做

有一个代码：

private void showResult() {
        if (mt == null) return;
        int result = -1;
        try {
            Log.d(LOG_TAG, "Try to get result");
            result = mt.get();
            Log.d(LOG_TAG, "get returns " + result);
            Toast.makeText(this, "get returns " + result, Toast.LENGTH_LONG).show();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (ExecutionException e) {
            e.printStackTrace();
        }
    }

为什么return它没有返回值，会发生什么？

我开始学习 AsyncTask，在一堂课中我看到了以下代码：

class MyTask extends AsyncTask<Void, Void, Void> {

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        tvInfo.setText("Begin");
    }

    @Override
    protected Void doInBackground(Void... params) {
        try {
            TimeUnit.SECONDS.sleep(2);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return null;
    }

    @Override
    protected void onPostExecute(Void result) {
        super.onPostExecute(result);
        tvInfo.setText("End");
    }
}

什么是 Void 类（带有大写字母），它的用途是什么，为什么不能使用常规的 void？

尝试为 Django 创建虚拟环境时遇到问题

文章对此进行了如下说明： 不带参数的等待方法 导致当前线程等待，直到另一个线程调用此对象的 notify() 方法或 notifyAll() 方法。换句话说，这个方法的行为就像它只是在做一个 wait(0) 调用一样。 https://java-en-blog.blogspot.com/2019/12/object-methods.html

有一个代码：

public class Main {
    public static void main(String[] args) {
        ThreadB threadB = new ThreadB();
        threadB.start();
        synchronized (threadB){
            try {
                threadB.wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        System.out.println(threadB.total);
    }
}

class ThreadB extends Thread {
    int total;

    @Override
    public void run() {
        for (int i = 0; i < 5; i ++){
            total+=i;
            try {
                sleep(500);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
/*        synchronized (this){
            notify();
        }*/
    }
}

一下子有两个问题：

1. 即使 notify() 方法被注释掉，线程也会运行到最后，这与上面写的内容相矛盾。
2. 如果取消注释notify()，就不是很清楚为什么调用这个方法是在线程内部（线程如何唤醒自己）

之前对于“什么是接口”这个问题，我回答的是“完全抽象的类”，也就是方法全是抽象的（没有body）的类，但最近开始处理迭代器和突然发现它的两个方法有一个主体：

总的来说，情况不是很清楚

我试图在互联网上找到文章，但基本上，他们都在谈论如何处理它。我想了解它是什么、在什么情况下发生、如何避免它等的基本知识。

Deque 中的 removeFirst() 和 pop() 有什么区别？

我看了几篇关于这个主题的文章，但是当我以前从未使用过 Comparator 时，那里给出的例子很难理解。

我正在尝试通过 id 更新数据库中的一行，但该行只是被删除了。请告诉我如何解决这个问题

public class MainActivity extends AppCompatActivity implements View.OnClickListener{
    
        Button btnAdd, btnRead, btnClear, btnUpd, btnDel;
        EditText etName, etEmail, etId;
    
        DBHelper dbHelper;
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
    
                        ................................................
    
            btnUpd = (Button) findViewById(R.id.btnUpd);
            btnUpd.setOnClickListener(this);
    
                        ................................................
    
            etName = (EditText) findViewById(R.id.etName);
            etEmail = (EditText) findViewById(R.id.etEmail);
            etId = (EditText) findViewById(R.id.etId);
    
            dbHelper = new DBHelper(this);
        }
    
        @Override
        public void onClick(View v) {
    
            String name = etName.getText().toString();
            String email = etEmail.getText().toString();
            String id = etId.getText().toString();
    
            SQLiteDatabase database = dbHelper.getWritableDatabase();
    
            ContentValues contentValues = new ContentValues();
    
    
            switch (v.getId()) {
    
                        ................................................
    
                case R.id.btnUpd:
                    if (id.equalsIgnoreCase("")){
                        break;
                    }
                    contentValues.put(DBHelper.KEY_MAIL, email);
                    contentValues.put(DBHelper.KEY_NAME, name);
                    int updCount = database.update(DBHelper.TABLE_CONTACTS, contentValues, DBHelper.KEY_ID + "= ?", new String[] {id});
    
                    Log.d("mLog", "updates rows count = " + updCount);
    
    
        case R.id.btnDel:
            if (id.equalsIgnoreCase("")){
                break;
            }
            int delCount = database.delete(DBHelper.TABLE_CONTACTS, DBHelper.KEY_ID + "=" + id, null);

            Log.d("mLog", "deleted rows count = " + delCount);
    
    
            }
            dbHelper.close();
        }
    }

有类似于 Google Play 的平台： https : //ilike.guru/nash-top/15-alternativ-play-market/ 将它们一起使用或代替 Play Market 是否有意义。如果应用程序也托管在替代平台上，Google 是否可以阻止该应用程序？而且，如果有某种意义，什么类似物更好用？

在 Intelij IDEA 中，这可以通过转到 Progect Structure - Progect 来完成（当然，如果我正确解释了我看到的内容）：

但在 Android Studio 中，同样的路径，却出现了完全不同的信息：

我是新手，参加过好几次面试，目前都没有成功。由于自我隔离和大多数企业向远程工作的转变，作为一名大三学生，找工作变得更加困难。对此，我在想，在没有行业经验的情况下，以自由职业者的身份开始工作是多么现实，在这种情况下，还有什么其他方法可以解决就业问题并获得经验？提前致谢！

有一个activity有2个fragment，当应用启动时，第一个fragment被启动，上面有个按钮，点击按钮后，第二个fragment应该被启动，如何实现呢？

我正在尝试制作一个在 TextView 中显示来自 Json 的文本的应用程序。目前我得到以下信息：

import retrofit2.Call;
import retrofit2.http.GET;
import retrofit2.http.Query;

public interface ApiService {
    /*
    Retrofit get annotation with our URL
    And our method that will return us the List of ContactList
    */
    @GET("/daily_json.js")
    Call<CurrencyOperations> getData(@Query("ID") String resourceName);
    //getMyJSON();
}

货币操作类：

import com.google.gson.annotations.Expose;
import com.google.gson.annotations.SerializedName;

public class CurrencyOperations {

    @SerializedName("Date")
    @Expose
    private String date;
    @SerializedName("PreviousDate")
    @Expose
    private String previousDate;
    @SerializedName("PreviousURL")
    @Expose
    private String previousURL;
    @SerializedName("Timestamp")
    @Expose
    private String timestamp;
    @SerializedName("Valute")
    @Expose
    private Valute valute;

    public String getDate() {
        return date;
    }

    public void setDate(String date) {
        this.date = date;
    }

    public String getPreviousDate() {
        return previousDate;
    }

    public void setPreviousDate(String previousDate) {
        this.previousDate = previousDate;
    }

    public String getPreviousURL() {
        return previousURL;
    }

    public void setPreviousURL(String previousURL) {
        this.previousURL = previousURL;
    }

    public String getTimestamp() {
        return timestamp;
    }

    public void setTimestamp(String timestamp) {
        this.timestamp = timestamp;
    }

    public Valute getValute() {
        return valute;
    }

    public void setValute(Valute valute) {
        this.valute = valute;
    }
}

美元类：

import com.google.gson.annotations.Expose;
import com.google.gson.annotations.SerializedName;

public class USD {

    @SerializedName("ID") // это связывает то, что находится в json и мой код (я так думаю)
    @Expose
    private String iD;
    @SerializedName("NumCode")
    @Expose
    private String numCode;
    @SerializedName("CharCode")
    @Expose
    private String charCode;
    @SerializedName("Nominal")
    @Expose
    private int nominal;
    @SerializedName("Name")
    @Expose
    private String name;
    @SerializedName("Value")
    @Expose
    private double value;
    @SerializedName("Previous")
    @Expose
    private double previous;

    public String getID() {
        return iD;
    }

    public void setID(String iD) {
        this.iD = iD;
    }

    public String getNumCode() {
        return numCode;
    }

    public void setNumCode(String numCode) {
        this.numCode = numCode;
    }

    public String getCharCode() {
        return charCode;
    }

    public void setCharCode(String charCode) {
        this.charCode = charCode;
    }

    public int getNominal() {
        return nominal;
    }

    public void setNominal(int nominal) {
        this.nominal = nominal;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public double getValue() {
        return value;
    }

    public void setValue(double value) {
        this.value = value;
    }

    public double getPrevious() {
        return previous;
    }

    public void setPrevious(double previous) {
        this.previous = previous;
    }

}

价值等级：

import com.google.gson.annotations.Expose;
import com.google.gson.annotations.SerializedName;

public class Valute {

    @SerializedName("USD")
    @Expose
    private USD uSD;

    public USD getUSD() {
        return uSD;
    }

    public void setUSD(USD uSD) {
        this.uSD = uSD;
    }
}

RetroClient 类：

import retrofit2.Retrofit;
import retrofit2.converter.gson.GsonConverterFactory;

public class RetroClient {

    /********
     * URLS
     *******/
    private static final String ROOT_URL = "https://www.cbr-xml-daily.ru/";

    /**
     * Get Retrofit Instance
     */
    private static Retrofit getRetrofitInstance() {
        return new Retrofit.Builder()
                .baseUrl(ROOT_URL)
                .addConverterFactory(GsonConverterFactory.create())
                .build();

        // !!!
    }

    /**
     * Get API Service
     *
     * @return API Service
     */
    public static ApiService getApiService() {
        return getRetrofitInstance().create(ApiService.class);
    }
}

MainActivity 类：

import retrofit2.Call;
import retrofit2.Callback;
import retrofit2.Response;

public class MainActivity extends AppCompatActivity {

    private TextView mTextView;
    private CurrencyOperations operations;
    private ArrayList<CurrencyOperations> mList;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        //Creating an object of our api interface
        ApiService api = RetroClient.getApiService();

        /**
         * Calling JSON
         */
        Call<CurrencyOperations> call = api.getData("bash");

        mTextView = (TextView) findViewById(R.id.text);
       // final CurrencyOperations operations = new CurrencyOperations();
      //  this.operations = new CurrencyOperations();
        final USD usd = new USD();

/*        HashMap<String, Object> hm;
        hm = new HashMap<String, Object>();
        //читаем что в себе хранит параметр balance
        hm.put(NAME, urls.getJSONObject(i).getString("name").toString());*/

        call.enqueue(new Callback<CurrencyOperations>() {
            @Override
            public void onResponse(Call<CurrencyOperations> call, Response<CurrencyOperations> response) {
                mTextView.setText(usd.getID()); // ???
            }

            @Override
            public void onFailure(Call<CurrencyOperations> call, Throwable t) {

            }
        });
    }
}

JSON：

{
    "Date": "2020-04-08T11:30:00+03:00",
    "PreviousDate": "2020-04-07T11:30:00+03:00",
    "PreviousURL": "\/\/www.cbr-xml-daily.ru\/archive\/2020\/04\/07\/daily_json.js",
    "Timestamp": "2020-04-07T23:00:00+03:00",
    "Valute": {
        "AUD": {
            "ID": "R01010",
            "NumCode": "036",
            "CharCode": "AUD",
            "Nominal": 1,
            "Name": "Австралийский доллар",
            "Value": 46.6312,
            "Previous": 46.2341
        },
        "AZN": {
            "ID": "R01020A",
            "NumCode": "944",
            "CharCode": "AZN",
            "Nominal": 1,
            "Name": "Азербайджанский манат",
            "Value": 44.4769,
            "Previous": 45.0383
        },
        "GBP": {
            "ID": "R01035",
            "NumCode": "826",
            "CharCode": "GBP",
            "Nominal": 1,
            "Name": "Фунт стерлингов Соединенного королевства",
            "Value": 93.0662,
            "Previous": 93.9429
        },
        "AMD": {
            "ID": "R01060",
            "NumCode": "051",
            "CharCode": "AMD",
            "Nominal": 100,
            "Name": "Армянских драмов",
            "Value": 15.0534,
            "Previous": 15.2434
        },
        "BYN": {
            "ID": "R01090B",
            "NumCode": "933",
            "CharCode": "BYN",
            "Nominal": 1,
            "Name": "Белорусский рубль",
            "Value": 29.5612,
            "Previous": 29.7155
        },
        "BGN": {
            "ID": "R01100",
            "NumCode": "975",
            "CharCode": "BGN",
            "Nominal": 1,
            "Name": "Болгарский лев",
            "Value": 41.9311,
            "Previous": 42.2257
        },
        "BRL": {
            "ID": "R01115",
            "NumCode": "986",
            "CharCode": "BRL",
            "Nominal": 1,
            "Name": "Бразильский реал",
            "Value": 14.274,
            "Previous": 14.2818
        },
        "HUF": {
            "ID": "R01135",
            "NumCode": "348",
            "CharCode": "HUF",
            "Nominal": 100,
            "Name": "Венгерских форинтов",
            "Value": 22.7589,
            "Previous": 22.7079
        },
        "HKD": {
            "ID": "R01200",
            "NumCode": "344",
            "CharCode": "HKD",
            "Nominal": 10,
            "Name": "Гонконгских долларов",
            "Value": 97.3224,
            "Previous": 98.5482
        },
        "DKK": {
            "ID": "R01215",
            "NumCode": "208",
            "CharCode": "DKK",
            "Nominal": 1,
            "Name": "Датская крона",
            "Value": 10.9849,
            "Previous": 11.0588
        },
        "USD": {
            "ID": "R01235",
            "NumCode": "840",
            "CharCode": "USD",
            "Nominal": 1,
            "Name": "Доллар США",
            "Value": 75.455,
            "Previous": 76.4074
        },
        "EUR": {
            "ID": "R01239",
            "NumCode": "978",
            "CharCode": "EUR",
            "Nominal": 1,
            "Name": "Евро",
            "Value": 82.012,
            "Previous": 82.6346
        },
        "INR": {
            "ID": "R01270",
            "NumCode": "356",
            "CharCode": "INR",
            "Nominal": 100,
            "Name": "Индийских рупий",
            "Value": 99.7673,
            "Previous": 10.0268
        },
        "KZT": {
            "ID": "R01335",
            "NumCode": "398",
            "CharCode": "KZT",
            "Nominal": 100,
            "Name": "Казахстанских тенге",
            "Value": 17.2656,
            "Previous": 17.3999
        },
        "CAD": {
            "ID": "R01350",
            "NumCode": "124",
            "CharCode": "CAD",
            "Nominal": 1,
            "Name": "Канадский доллар",
            "Value": 53.8004,
            "Previous": 54.1244
        },
        "KGS": {
            "ID": "R01370",
            "NumCode": "417",
            "CharCode": "KGS",
            "Nominal": 100,
            "Name": "Киргизских сомов",
            "Value": 88.877,
            "Previous": 89.9985
        },
        "CNY": {
            "ID": "R01375",
            "NumCode": "156",
            "CharCode": "CNY",
            "Nominal": 1,
            "Name": "Китайский юань",
            "Value": 10.696,
            "Previous": 10.7725
        },
        "MDL": {
            "ID": "R01500",
            "NumCode": "498",
            "CharCode": "MDL",
            "Nominal": 10,
            "Name": "Молдавских леев",
            "Value": 40.6218,
            "Previous": 40.9691
        },
        "NOK": {
            "ID": "R01535",
            "NumCode": "578",
            "CharCode": "NOK",
            "Nominal": 10,
            "Name": "Норвежских крон",
            "Value": 73.5924,
            "Previous": 72.5616
        },
        "PLN": {
            "ID": "R01565",
            "NumCode": "985",
            "CharCode": "PLN",
            "Nominal": 1,
            "Name": "Польский злотый",
            "Value": 18.0757,
            "Previous": 18.1099
        },
        "RON": {
            "ID": "R01585F",
            "NumCode": "946",
            "CharCode": "RON",
            "Nominal": 1,
            "Name": "Румынский лей",
            "Value": 16.9787,
            "Previous": 17.0972
        },
        "XDR": {
            "ID": "R01589",
            "NumCode": "960",
            "CharCode": "XDR",
            "Nominal": 1,
            "Name": "СДР (специальные права заимствования)",
            "Value": 102.4845,
            "Previous": 103.7895
        },
        "SGD": {
            "ID": "R01625",
            "NumCode": "702",
            "CharCode": "SGD",
            "Nominal": 1,
            "Name": "Сингапурский доллар",
            "Value": 52.9212,
            "Previous": 53.2604
        },
        "TJS": {
            "ID": "R01670",
            "NumCode": "972",
            "CharCode": "TJS",
            "Nominal": 10,
            "Name": "Таджикских сомони",
            "Value": 73.903,
            "Previous": 74.8358
        },
        "TRY": {
            "ID": "R01700J",
            "NumCode": "949",
            "CharCode": "TRY",
            "Nominal": 1,
            "Name": "Турецкая лира",
            "Value": 11.2234,
            "Previous": 11.2795
        },
        "TMT": {
            "ID": "R01710A",
            "NumCode": "934",
            "CharCode": "TMT",
            "Nominal": 1,
            "Name": "Новый туркменский манат",
            "Value": 21.5894,
            "Previous": 21.8619
        },
        "UZS": {
            "ID": "R01717",
            "NumCode": "860",
            "CharCode": "UZS",
            "Nominal": 10000,
            "Name": "Узбекских сумов",
            "Value": 78.0865,
            "Previous": 79.4999
        },
        "UAH": {
            "ID": "R01720",
            "NumCode": "980",
            "CharCode": "UAH",
            "Nominal": 10,
            "Name": "Украинских гривен",
            "Value": 27.8478,
            "Previous": 28.0394
        },
        "CZK": {
            "ID": "R01760",
            "NumCode": "203",
            "CharCode": "CZK",
            "Nominal": 10,
            "Name": "Чешских крон",
            "Value": 30.039,
            "Previous": 29.8461
        },
        "SEK": {
            "ID": "R01770",
            "NumCode": "752",
            "CharCode": "SEK",
            "Nominal": 10,
            "Name": "Шведских крон",
            "Value": 75.4437,
            "Previous": 75.2515
        },
        "CHF": {
            "ID": "R01775",
            "NumCode": "756",
            "CharCode": "CHF",
            "Nominal": 1,
            "Name": "Швейцарский франк",
            "Value": 77.5408,
            "Previous": 78.1901
        },
        "ZAR": {
            "ID": "R01810",
            "NumCode": "710",
            "CharCode": "ZAR",
            "Nominal": 10,
            "Name": "Южноафриканских рэндов",
            "Value": 41.194,
            "Previous": 40.0399
        },
        "KRW": {
            "ID": "R01815",
            "NumCode": "410",
            "CharCode": "KRW",
            "Nominal": 1000,
            "Name": "Вон Республики Корея",
            "Value": 62.1042,
            "Previous": 62.1658
        },
        "JPY": {
            "ID": "R01820",
            "NumCode": "392",
            "CharCode": "JPY",
            "Nominal": 100,
            "Name": "Японских иен",
            "Value": 69.3106,
            "Previous": 70.0247
        }
    }
}

json 链接：https ://www.cbr-xml-daily.ru/daily_json.js

这个项目在 GitHub 上：https ://github.com/Nikolui333/JSONTestL

由于某种原因，我无法在 textView 中显示美元 ID 数据。PS我知道，很可能，我犯的错误很明显，但我以前从未这样做过，所以我不知道如何使代码工作。

我经常遇到这样一种情况，我面临一个特定的任务（例如，一个测试任务），为此需要使用我以前从未使用过的技能和技术。通常搜索信息需要花费大量时间，我必须搜索大量“无用”信息，然后才能找到至少与我正在解决的问题相关的信息，同时又不会过时。直到几个月前，我才学会了如何使用 GitHub 搜索（我了解到您可以搜索整个站点，而不仅仅是特定帐户）。请告诉我如何快速找到必要的信息

我阅读和观看了很多关于这个主题的材料，意见往往截然相反。有人说你需要主要依靠书本，从头到尾，相反，实践是首要的，只把书作为可以提高你对问题理解的材料是有意义的（否则，在这种情况下，花费的时间不值得非常谦虚的最终结果）。一点澄清：我还没有开始我的旅程，我已经编程了一年多一点，在那段时间我学习了JavaRush编程，阅读了Head First书籍“Java编程”，掌握了部分同一出版商关于 Android 开发主题的书，编写了几个应用程序（主要针对 Android），参加了 5 次面试（并非全部针对 Android 开发人员），几次测试任务失败。

主要的问题是，即使经过一年的编程，我也无法制定出最优的学习策略，对此，请问各位经验丰富的同志，您认为哪种学习方式最有效，为什么？

观看有关编程的视频教程。为了不手动输入代码，我在 GitHub 上寻找现成的仓库。问题是，如果应用程序是由几节课创建的，那么找到正确的存储库是相当困难的，早期版本不断出现。我试图搜索视频中代码中存在的行，但问题是 GitHub 并没有完全搜索整行，而是找到具有相同关键字的结果。我该怎么做才能获得准确的搜索结果？例如，我输入以下行：

JSONArray jsonarray = jsonResponse.getJSONArray("response");

而且我需要搜索只返回整行所在的那些代码片段。