小第寫左個android class 大約係咁

public class MainActivity extends Activity {
private Boolean isBoy = false;

public void onCreate(Bundle savedInstanceState){
checkBoy();
Log.d("1", new Boolean(isBoy).toString());
}

public void checkBoy(){
Thread t = new Thread(){
public void run(){
try{
isBoy = true;
Log.d("2", new Boolean(isBoy).toString());
}catch (Exception e){
e.printStackTrace();
}
}
};
t.start();
}
}

result:
Log -> 2 true;
Log -> 1 false;
點解到最後出面個isBoy 仲係false 嘅?
真心求教