如何在android应用程序中加载初始视图？

我一直在开发这个应用程序，这是我上学期参加的一门课作业的一部分，但我不能完全让它工作。根据反馈，我的主要问题是“没有初始视图加载来启动游戏”，所以应用程序崩溃了。 这是我的活动课：

public class GuessMasterActivity extends AppCompatActivity {
    private TextView entityName;
    private TextView ticketsum;
    private Button guessButton;
    private EditText userIn;
    private Button btnclearContent;
    private String user_input;
    private ImageView entityImage;
    String answer;
    private int numOfEntities;
    private Entity[] entities;
    private int numOfTickets;
    private int[] tickets;
    String entName;
    int entityid =0;
    int currentTicketWon = 0;
    Politician trudeau = new Politician("Justin Trudeau", new Date("December", 25, 1971), "Male", "Liberal", 0.25);
    Singer dion = new Singer("Celine Dion", new Date("March", 30, 1968), "Female", "La voix du bon Dieu", new Date("November", 6, 1981), 0.5);
    Person myCreator = new Person("myCreator", new Date("September", 1, 2000), "Female", 1);
    Country usa = new Country("United States", new Date("July", 4, 1776), "Washington D.C.", 0.1);

    public GuessMasterActivity() {
        numOfEntities = 0;          //Initialize counter variables to zero
        numOfTickets = 0;
        entities = new Entity[100]; //Max number of entities possible in the game is 100

    }


    public void addEntity(Entity entity) {          //Adds selected entity to the game
        entities[numOfEntities++] = entity.clone(); //Invokes clone function to create a copy of selected entity and stores copy in entities array
    }



    public void playGame() {                                //Runs the game with selected entity

            userIn.getText().clear();
            int entityId = genRandomEntityId();

            Entity entity = entities[entityId];
            entityName.setText(entity.getName());
            String answer = userIn.getText().toString();                            //Reads user input
            answer = answer.replace("\n", "").replace("\r", "");

            if (answer.equals("quit")) {                                //Ends game if user inputs quit
                System.exit(0);
            }

            Date date = new Date(answer);

            if (date.precedes(entity.getBorn())) {                      //Evaluates user input
                AlertDialog.Builder Incorrect = new AlertDialog.Builder(GuessMasterActivity.this);
                Incorrect.setTitle("Incorrect");
                Incorrect.setMessage("Try a later date");

                Incorrect.setNegativeButton("Ok", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialogInterface, int i) {
                        Toast.makeText(getBaseContext(),"Loading...",Toast.LENGTH_SHORT).show();
                    }
                });
                AlertDialog dialog = Incorrect.create();
                dialog.show();
            } else if (entity.getBorn().precedes(date)) {
                AlertDialog.Builder Incorrect2 = new AlertDialog.Builder(GuessMasterActivity.this);
                Incorrect2.setTitle("Incorrect");
                Incorrect2.setMessage("Try an earlier date");

                Incorrect2.setNegativeButton("Ok", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialogInterface, int i) {
                        Toast.makeText(getBaseContext(),"Loading...",Toast.LENGTH_SHORT).show();
                    }
                });
                AlertDialog dialog = Incorrect2.create();
                dialog.show();
            } else {
                currentTicketWon = entity.getAwardedTicketNumber();
                this.numOfTickets = this.numOfTickets + entity.getAwardedTicketNumber(); //Updates total number of tickets for this game based on difficulty of selected entity
                AlertDialog.Builder win = new AlertDialog.Builder(GuessMasterActivity.this);
                win.setTitle("You Won");
                win.setMessage("Bingo"+entity.closingMessage());

                win.setNegativeButton("Continue", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialogInterface, int i) {
                        Toast.makeText(getBaseContext(),"You won"+currentTicketWon+"tickets",Toast.LENGTH_SHORT).show();
                    }
                });
                AlertDialog dialog = win.create();
                dialog.show();
                ticketsum.setText(numOfTickets);
                ContinueGame();
            }

    }
    public void ImageSetter(){
        ImageView imgView = findViewById(R.id.entityImage);
        switch(entName){
            case("Justin Trudeau"):
                imgView.setImageResource(R.drawable.justint);
                break;
            case("Celine Dion"):
                imgView.setImageResource(R.drawable.celidion);
                break;
            case("United States"):
                imgView.setImageResource(R.drawable.usaflag);
                break;
            case("myCreator"):
                imgView.setImageResource(R.drawable.pic);
                break;
        }
    }
    public void ContinueGame(){
        entityid = genRandomEntityId();
        Entity entity = entities[entityid];
        entName = entity.getName();
        ImageSetter();
        entityName.setText(entName);
    }

    public int genRandomEntityId() {                                    //Selects random integer in the range of 0-the number of entities in the game
        Random randomNumber = new Random();
        return randomNumber.nextInt(numOfEntities);
    }
    public void changeEntity(){
        userIn.setText("");
        playGame();
    }

    void welcomeToGame(Entity entity){
        AlertDialog.Builder welcomealert = new AlertDialog.Builder(GuessMasterActivity.this);
        welcomealert.setTitle("GuessMaster Game v3");
        welcomealert.setMessage(entity.welcomeMessage());
        welcomealert.setCancelable(false);

        welcomealert.setNegativeButton("START_GAME", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                Toast.makeText(getBaseContext(),"Game is Starting. . . Enjoy", Toast.LENGTH_SHORT).show();
            }
        });
        AlertDialog dialog = welcomealert.create();
        dialog.show();

    }
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        addEntity(usa);
        addEntity(dion);
        addEntity(trudeau);
        addEntity(myCreator);
        setContentView(R.layout.activity_guess_master);
        guessButton = (Button) findViewById(R.id.btnGuess);
        userIn = (EditText)findViewById(R.id.guessInput);
        ticketsum = (TextView)findViewById(R.id.ticket);
        entityImage = (ImageView)findViewById(R.id.entityImage);
        entityName = (TextView)findViewById(R.id.entityName);
        btnclearContent = (Button) findViewById(R.id.btnClear);
        btnclearContent.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                changeEntity();
            }
        });
        guessButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                playGame();
            }
        });
        final GuessMasterActivity gm = new GuessMasterActivity();
    }
}

以及XML布局：

    <?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.david.guessmaster.GuessMasterActivity">

    <TextView
        android:id = "@+id/ticket"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
    <ImageView
        android:id="@+id/entityImage"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />
    <TextView
        android:id = "@+id/entityName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />
    <EditText
        android:id = "@+id/guessInput"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

    <TableLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content">

        <LinearLayout>

            <Button
                android:id="@+id/btnGuess"
                style="@style/Widget.AppCompat.Button"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content" />

            <Button
                android:id="@+id/btnClear"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content" />
        </LinearLayout>
    </TableLayout>

</LinearLayout>

---

我错过了什么/哪里出了问题？我觉得我一定是误解了应用程序的流程

如果应用程序崩溃，请发布崩溃日志。你对发生的事情的描述告诉我们什么。它不会因为“没有初始视图加载”而崩溃，也不会因为崩溃而显示任何视图。虽然我可以在你的代码中看到一些奇怪的地方（活动很少->从来没有构造函数，也不应该通过new关键字来创建）。由于某种原因，它似乎不再崩溃，但它在开始时不会加载任何图片。所有内容都应该在onCreate中而不是构造函数中吗？然后我就不需要最后的GuessMasterActivity gm=新的GuessMasterActivity行了，对吗？