创建新对象后ArrayList为空

Question

我想创建一个使用for循环在我的MainActivity.java中的虚拟对象的ArrayList。这似乎是我得到我创建的每个对象的对象引用做工精细：

for(int i=0; i < 10; i++){ 
    new TaskObjects("Title " + i, "Category " + i, "Description " + i, i + 10); 
    Log.d("For Loop", "" + i); 
} 

我有一个日志（this.toString（））返回10次这样的构造函数中：

d/ARRAY：[email protected]（每个不同ID）

TaskObjects类：

public class TaskObjects { 
    private String title; 
    private String category; 
    private String description; 
    private int taskPosterID; 
    private ArrayList<TaskObjects> tasksArray = new ArrayList<>(); 

    public TaskObjects(String title, String category, String description, int taskPosterID){ 
    this.title = title; 
    this.category = category; 
    this.description = description; 
    this.taskPosterID = taskPosterID; 
    tasksArray.add(this); 
    Log.d("ARRAY",this.toString()); 
    } 
    //getters and setters 
} 

然而，当我尝试返回所述阵列的尺寸，则返回0

Answer 1

public class TaskObjects { 
    private String title; 
    private String category; 
    private String description; 
    private int taskPosterID; 


    public TaskObjects(String title, String category, String description, int taskPosterID){ 
    this.title = title; 
    this.category = category; 
    this.description = description; 
    this.taskPosterID = taskPosterID; 


    } 
    //getters and setters 
} 

MainActivity.java

private ArrayList<TaskObjects> tasksArray = new ArrayList<>(); 


@Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 

     setContentView(R.layout.main_activity); 

for(int i=0; i < 10; i++){ 
TaskObjects task= new TaskObjects("Title " + i, "Category " + i, "Description " + i, i + 10); 
tasksArray.add(task); 
    Log.d("For Loop", "" + i); 
} 

} 

Answer 2

您必须使tasksArray为静态。否则的TaskObjects每个实例创建一个新的（=空）taskArray

private static ArrayList<TaskObjects> tasksArray = new ArrayList<>();