如何在 Java 中将对象添加到 ArrayList
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How to add an object to an ArrayList in Java
提问by Johnfranklien
I want to add an object to an ArrayList, but each time I add a new object to an ArrayListwith 3 attributes: objt(name, address, contact), I get an error.
我想向 an 添加一个对象ArrayList，但是每次我向ArrayList具有 3 个属性的an 添加一个新对象时objt(name, address, contact)，我都会收到错误消息。
import java.util.ArrayList;
import java.util.Scanner;
public class mainClass {
public static void main(String args[]){
Scanner input = new Scanner(System.in);
System.out.println("Plz enter Name : ");
String name = input.nextLine();
System.out.println("Plz enter Address : ");
String address = input.nextLine();
System.out.println("Plz enter ContactNo : ");
String contact = input.nextLine();
ArrayList<Data> Contacts = new ArrayList<Data>();
Data objt = new Data();
Contacts.add(objt.Data(name, address, contact));
}
}
Here, Datais the class of which I'm trying to create an object and pass it to an ArrayList.
在这里，Data是我试图创建一个对象并将其传递给ArrayList.
public class Data {
private String name = "";
private String address = "";
private String cell = "";
public void Data(String n, String a, String c){
name = n;
address = a;
cell = c;
}
public void printData(){
System.out.println("Name\tAddress\tContactNo");
System.out.println(name + "\t" + address + "\t" + cell);
}
}
采纳答案by SudoRahul
You need to use the newoperator when creating the object
new创建对象时需要使用运算符
Contacts.add(new Data(name, address, contact)); // Creating a new object and adding it to list - single step
or else
要不然
Data objt = new Data(name, address, contact); // Creating a new object
Contacts.add(objt); // Adding it to the list
and your constructor shouldn't contain void. Else it becomes a method in your class.
并且您的构造函数不应包含void. 否则它会成为您班级中的一个方法。
public Data(String n, String a, String c) { // Constructor has the same name as the class and no return type as such
回答by Umar Asghar
Try this one:
试试这个：
Data objt = new Data(name, address, contact);
Contacts.add(objt);
回答by Prashant Bhagwani
You have to use new operator here to instantiate. For example:
您必须在此处使用 new 运算符来实例化。例如：
Contacts.add(new Data(name, address, contact));
回答by moha
change Date to Object which is between parenthesis
将日期更改为括号之间的对象
回答by saibaba vali
Contacts.add(objt.Data(name, address, contact));
This is not a perfect way to call a constructor. The constructor is called at the time of object creation automatically. If there is no constructor java class creates its own constructor.
这不是调用构造函数的完美方式。构造函数在对象创建时自动调用。如果没有构造函数，java 类会创建自己的构造函数。
The correct way is:
正确的方法是：
// object creation.
Data object1 = new Data(name, address, contact);
// adding Data object to ArrayList object Contacts.
Contacts.add(object1);
