創建新對象後ArrayList爲空

Question

我想創建一個使用for循環在我的MainActivity.java中的虛擬對象的ArrayList。這似乎是我得到我創建的每個對象的對象引用做工精細：

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

我有一個日誌（this.toString（））返回10次這樣的構造函數中：

d/ARRAY：com.mail.app_appname.TaskObjects@af4fd26（每個不同ID）

TaskObjects類：

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，當我嘗試返回所述陣列的尺寸，則返回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

您必須使tasksArray爲靜態。否則的TaskObjects每個實例創建一個新的（=空）taskArray

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