Question

我有一个问题，我想设置并从android的setter和getter方法中获取ArrayList。但我是Android和Java的新手，不知道该怎么做？任何人都可以帮我解决这个问题吗？

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

为了更好的封装/ OO设计，我会做以下

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 3

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

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

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

Answer 4

通常，getter和setter方法用于从

赋值变量和获取变量值

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;
    }

Int

相同

int id;

    public int getId() {
        return id;
    }

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

Answer 5

我不熟悉android。但是在JAVA中，如果你想使用set和get方法，你需要先声明List。

private List arrayList = new ArrayList();

public List getArrayList() {
    return arrayList;
}

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

Answer 6

请试试这个

  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

Answer 7

试试这些

public ArrayList getArrayList() {
    return arraylist;
}

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

在java中使用getter和Setter for arraylist

7 个答案: