保存ArrayList項目

Question

我正在創建一個應用程序，我必須一遍又一遍地引用相同的數據。我是新來的編碼，所以我不知道我是否正確地做了。現在我用setter和getters來創建一個類來存儲我想要的數據。

（Item類）

public class PlayerList { 
    private String score; 
    private String team; 
    private String name; 
    private String scoreWeek; 
    private String position; 
    private String goals; 
    private String assists; 
    private String yellowCards; 
    private String redCards; 
    private int iconID; 
    public PlayerList(String name, String team, String score, String scoreWeek, String position, 
      String goals, String assists, String yellowCards, String redCards, int iconID){ 
     super(); 
     this.score= score; 
     this.team = team; 
     this.name = name; 
     this.scoreWeek = scoreWeek; 
     this.position= position; 
     this.goals = goals; 
     this.assists = assists; 
     this.yellowCards = yellowCards; 
     this.redCards = redCards; 
     this.iconID= iconID; 
    } 
    public String getScore() { 
     return score; 
    } 
    public void setScore(String score) { 
     this.score = score; 
    } 
    public String getTeam() { 
     return team; 
    } 
    public void setTeam(String team) { 
     this.team = team; 
    } 
    public String getName() { 
     return name; 
    } 
    public void setName(String name) { 
     this.name = name; 
    } 
    public String getScoreWeek() { 
     return scoreWeek; 
    } 
    public void setScoreWeek(String scoreWeek) { 
     this.scoreWeek = scoreWeek; 
    } 
    public String getPosition() { 
     return position; 
    } 
    public void setPosition(String position) { 
     this.position = position; 
    } 
    public String getGoals() { 
     return goals; 
    } 
    public void setGoals(String goals) { 
     this.goals = goals; 
    } 
    public String getAssists() { 
     return assists; 
    } 
    public void setAssists(String assists) { 
     this.assists = assists; 
    } 
    public String getYellowCards() { 
     return yellowCards; 
    } 
    public void setYellowCards(String yellowCards) { 
     this.yellowCards = yellowCards; 
    } 
    public String getRedCards() { 
     return redCards; 
    } 
    public void setRedCards(String redCards) { 
     this.redCards = redCards; 
    } 
    public int getIconID() { 
     return iconID; 
    } 
    public void setIconID(int iconID) { 
     this.iconID = iconID; 
    } 
} 

然後，我提出在該數據被編輯，並把成陣列另一個類。

（編輯碼）

public class Players extends Activity { 
    private ArrayList<PlayerList> stateList = new ArrayList<PlayerList>(); 


    public Players(){ 
     PlayerList _states = new PlayerList("Name","Team","Score","Score Week", "Position", 
       "Goals", "Assists","Yellow Cards","Red Cards", R.drawable.client_icon); 
     stateList.add(_states); 

     PlayerList _states1 = new PlayerList("Name2","Team","Score","Score Week", "Position", 
       "Goals", "Assists","Yellow Cards","Red Cards", R.drawable.client_icon); 
     stateList.add(_states1); 

     PlayerList _states2 = new PlayerList("Name3","Team","Score","Score Week", "Position", 
       "Goals", "Assists","Yellow Cards","Red Cards", R.drawable.client_icon); 
     stateList.add(_states2); 

    } 
} 

編輯數據並將其添加到一個單獨的數組列表後，如何可以參考回數據。例如在應用程序的其他部分，我需要參考玩家的分數？我想將數據保存在SharedPreferences中，但它只保存集合。請幫忙。我想把它發送到另一個活動。例如，我希望它在主屏幕上顯示玩家分數。以及在一個談論球隊球員的屏幕上。

Answer 1

如果您不想將數據直接傳遞給使用它的函數，則必須將其保存在某處。這被稱爲數據持久性。它通常意味着該過程將在創建數據之前死亡。在Java中，這個術語是鬆散地用來指代事件之間持續的數據，甚至是方法調用，而不一定是過程。在Java中，持久性通常使用序列化完成。你可以讓你Serializable類這樣

​​

一個對象只能進行序列化，如果每一個對象包含可序列化。一旦一個對象是可序列化的，它就可以寫入一個流中（也可以寫入一個文件）並從中讀取。其他代碼可以檢索序列化的數據。 ObjectOutputStream和ObjectInputStream能夠讀取和寫入可串行化的數據。在讀取對象到相應的類型時，您必須將這些對象進行投射。

如果我讀了你的問題錯了，你真的只是不知道如何訪問ArrayList，試試這個：

int score = null; 
for (PlayerList pl: myArrayList) { 
    if(pl.getName() == teamName) 
     score = pl.getScore(); 
} 
System.out.println(score == null ? "No score available.": score); 

或者，讓所有的球隊的成績：

for (PlayerList pl: myArrayList) { 
    System.out.println(pl.getScore()); 
}