在java中使用Getter和Setter for arraylist

Question

我有一個問題，我想設置並從android的setter和getter方法獲取ArrayList。但我是新來的android和Java，不知道該怎麼做？任何人都可以幫我解決這個問題嗎？

Answer 1

示例 -

import java.util.ArrayList; 
import java.util.List; 

public class Test { 

List<String> list = null; 

public List<String> getList() { 
    return list; 
} 

public void setList(List<String> list) { 
    this.list = list; 
} 

public static void main(String[] args) { 
    Test test = new Test(); 
    List<String> sample = new ArrayList<String>(); 
    sample.add("element 1"); 
    test.setList(sample); 
    List<String> sample1 = test.getList(); 
} 
} 

Answer 2

嘗試這些

public ArrayList getArrayList() { 
    return arraylist; 
} 

public void setArrayList(ArrayList arraylist) { 
    this.arraylist = arraylist; 
} 

Answer 3

我不熟悉的Android。 但是在JAVA中，如果你想使用set和get方法，你需要首先聲明List。

private List arrayList = new ArrayList(); 

public List getArrayList() { 
    return arrayList; 
} 

public void setArrayList(List arrayList) { 
    this.arrayList = arrayList; 
} 

Answer 4

ArrayList<String> arrList = new ArrayList<String>(); 

    public ArrayList<String> getArrList() { 
     return arrList; 
    } 

    public void setArrList(ArrayList<String> arrList) { 
     this.arrList = arrList; 
    } 

Answer 5

一般getter和setter方法是變量賦值，並從該

There is not any difference of getter and setter methods for arraylist or for int of a class 

ArrayList<String> arrList; 

    public ArrayList<String> getArrList() { 
     return arrList; 
    } 

    public void setArrList(ArrayList<String> arrList) { 
     this.arrList = arrList; 
    } 

相同的變量值詮釋

int id; 

    public int getId() { 
     return id; 
    } 

    public void setId(int id) { 
     this.id = id; 
    } 

Answer 6

爲了更好的封裝/ OO設計我會做以下

import java.util.ArrayList; 
import java.util.Arrays; 
import java.util.List; 

public class TestListGetterSetter { 
List<String> list = new ArrayList<>(); 

//Return copy of the list 
public List<String> getList() { 
    return new ArrayList<>(list); 
} 

// Copy source list into destination list 
public void setList(List<String> listToBeSet) { 
    if (listToBeSet != null) 
     this.list.addAll(listToBeSet); 
} 

public static void main(String[] args) { 
    TestListGetterSetter testListGetterSetter = new TestListGetterSetter(); 

    List<String> clientList = new ArrayList<>(Arrays.asList("foo", "bar", "HiHa")); 

    testListGetterSetter.setList(clientList); 
    System.out.println("TestListGetterSetter.list before clientList modification = " + testListGetterSetter.getList()); 

    //Now you can change "clientList" without affecting testListGetterSetter object 
    clientList.add("1"); 
    System.out.println("clientList modified List = " + clientList); 
    System.out.println("TestListGetterSetter.list after clientList modification = " + testListGetterSetter.getList()); 
    } 
} 

Answer 7

請一定要試試這個

public static ArrayList<books> al = new ArrayList<books>(); 
    books book=new books(id,name,type); 
       book1 b1=new book1(id,name,type); 
       al.add(book); 
       al.add(book1); //error at book1