我有一个名为MainActivity的活动，其中包含public class Test {
public static void main(String[] args) {
Scanner scan = new Scanner (System.in);
AddressBook ad1 = new AddressBook();
String firstName="";
String lastName="";
String key="";
int choice=0;
do{
System.out.println("********************************************************************************");
System.out.println("Welcome to the Address book. Please pick from the options below.\n");
System.out.println("1.Add user \n2.Remove user \n3.Edit user \n4.List Contact \n5.Sort contacts \n6.Exit");
System.out.print("Please enter a choice: ");
choice = scan.nextInt();
if(choice==1){
//Add user
System.out.print("Please enter firstname: ");
firstName=scan.next();
System.out.print("Please enter lastname: ");
lastName=scan.next();
Address address = new Address();
key = lastName.concat(firstName);
Person person = new Person(firstName,lastName);
ad1.addContact(key,person);
System.out.println("key: " + key);
}
else if(choice==2){
//Remove user
System.out.println("Please enter name of user to remove: ");
scan.useDelimiter(System.getProperty("line.separator"));
key=scan.next();
System.out.println("name:" + key);
ad1.removeContact(key);
}
else if(choice==3){
//Edit user
}
else if(choice==4){
//List contact
ad1.listAllContacts();
}
else if(choice==5){
//Sort contacts
}
}while(choice!=6);
}
}
。使用导航组件，我已经设置了可以从FirstFragment打开的单个片段是FirstFragment。我还启用了后退按钮，以便能够从SecondFragment导航到SecondFragment。问题是当我回到FirstFragment时，未触发了FirstFragment方法。在这种情况下会触发什么方法？怎么知道我何时从onStart()回到SecondFragment？
答案 0 :(得分：1)
onCreateView（）方法。该片段的布局在onCreateView（）方法中被放大。这样您将看到第一个片段屏幕。