我知道之前已经多次询问过，但即使查看类似的帖子，我也无法弄清楚这一点。
这是我的MainActivity类：
package binchtitsinc.adventuregameamlior;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity {
private int compteur;
private TextView display;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
compteur = 0;
display = (TextView) findViewById(R.id.Afficheur);
display.setText("Count is: " + compteur);
Game theGame;
theGame = new Game();
theGame.play();
}
public void plusOne(View button){
compteur=compteur+1;
display.setText("Count is: "+compteur);
}
public void toUser(String texte){
display.setText("Message:"+texte);
}
}
我已经检查过，ID是正确的（R.id.Afficheur）。 真正奇怪的是，当我在该课堂上打电话给用户时，它的工作完美无瑕。但是，当我从另一个类调用该方法时（这里，＆＃34; Game＆＃34;），我得到了我在标题中粘贴的错误。
这是我课堂游戏的开始：
package binchtitsinc.adventuregameamlior;
/**
* Created by Leo on 11/04/16.
*/
public class Game {
//Attributes
private Parser parser;
private Energy energy;
private Room currentRoom;
private Room goalRoom;
private MainActivity main;
private DirectionLexicon dirVocabulary;
private CommandLexicon commandVocabulary;
private boolean wantsToQuit;
private boolean hasTheItem;
//Methods
//Public methods
/**
* This is a constructor.
* It creates the game and initialise its internal map.
*/
public Game() {
dirVocabulary = new DirectionLexicon();
commandVocabulary = new CommandLexicon();
createRooms();
energy = new Energy();
main = new MainActivity();
parser = new Parser(2); //the parameter 2 here in the call to the constructor of Parser means that in this game
// sentences typed in by the player will contain at most 2 words.
}
/**
* Main play routine. Loops until end of play.
*/
public void play() {
printWelcome();
// Enter the main command loop. Here we repeatedly read commands and
// execute them until the game is over.
wantsToQuit = false;
hasTheItem = false;
while (!wantsToQuit) {
if (!currentRoom.isSameRoomAs(goalRoom) || !hasTheItem) {
// && is the logical operator AND
// ! is the logical operator NOT
// currentRoom.isSameRoomAs(goalRoom) checks whether we have reached the goal.
parser.getAndAnalyzeSentence();
if (parser.lastSentenceLength() > 0) {// Here we know the player has typed in at list 1 word
if (commandVocabulary.isLexiconWord(parser.word(1))) { // here we know the firs word typed in corresponds to a known command
if (energy.getEnergy() <= energy.move) { // If the remaining energy is less than the amount required to move, it's over
main.toUser("You don't have any more energy. You're dead.");
printwelcome（）调用main.toUser（）方法，它也在粘贴代码的末尾：main.toUser（＆＃34;你没有更多的精力。你和＃39;死了＆＃34;）。
有什么想法吗？