Question

如何将元素动态添加到类中。我有一个列表视图组件和String变量中的信息列表。它们由星号和＃分隔。我需要ListView的适配器并使用此方法。静态方法还可以。但是动态方法不起作用。

这是我的代码：

public class transModel{
     public String DateTime;
     public String Action;
     public String Amount;
     public String DestAccount;
     public transModel(String DateTime, String Action, String Amount, String DestAccount){
            this.DateTime = DateTime;
            this.Action = Action;
            this.Amount = Amount;
            this.DestAccount = DestAccount;
     }
}
class Mylistadapter extends BaseAdapter{
    transModel[] transModels;
    public Mylistadapter (transModel[] transModels){
         this.transModels = transModels;
    }
    @Override
    public View getView(int i, View convertView, ViewGroup viewGroup) {
        View view1 = LayoutInflater.from(view.getContext()).inflate(R.layout.report_list,null);
……
            return view1;
    }
}

.
.
///////////////   Main program  ///////////////////
result1 = “a#b#c#d * e#f#g#h * i#j#k#l”; 
String[] items = result1.split(Pattern.quote("*"));
String[] items1;
transModel[] transModels = null;
 transModel tt =  new transModel("","","","");
 for (String item : items) {
      items1 = item.split(Pattern.quote("#"));
      tt.DateTime = items1[0];
      tt.Action = items1[1];
      tt.Amount = items1[2];
      tt.DestAccount = items1[3];
 //                        transModels = new transModel[]{tt};
                    }
 ListView lview = (ListView) view.findViewById(R.id.list_trans);
 lview.setAdapter(new Mylistadapter(transModels));
 /*
 Static way : 
 transModel tmodel1 = new transModel(“a”,”b”,”c”,”d”);
 transModel tmodel2 = new transModel(“e”,”f”,”g”,”h”);
 transModel tmodel3 = new transModel(“i”,”j”,”k”,”l”);
 transModel[] transModels = new transModel[]{tmodel1,tmodel2,tmodel3};
 */

Answer 1

您将项目错误地添加到了数组中。以下代码不正确：

String[] items = result1.split(Pattern.quote("*"));
String[] items1;
transModel[] transModels = null;
transModel tt =  new transModel("","","","");
for (String item : items) {
      items1 = item.split(Pattern.quote("#"));
      tt.DateTime = items1[0];
      tt.Action = items1[1];
      tt.Amount = items1[2];
      tt.DestAccount = items1[3];
//                        transModels = new transModel[]{tt};
}

首先，您永远不会用以下方法初始化数组大小：

transModel[] transModels = null;

第二，您永远不会在每个循环中都设置项目。

要解决此问题，您需要使用以下内容初始化数组的大小：

transModel[] transModels = new TransModel[10];

然后按位置设置每个项目。

这里是示例代码：

String[] items = result1.split(Pattern.quote("*"));

// initialize the length of transModel by the length of items.
transModel[] transModels = new transMode[items.length];

// use traditional for loop so we can use the item index.
for (int i = 0; i < items.length; i++) {
      transModel tt =  new transModel("","","","");
      String[] items1 = items[i].split(Pattern.quote("#"));
      tt.DateTime = items1[0];
      tt.Action = items1[1];
      tt.Amount = items1[2];
      tt.DestAccount = items1[3];

      // set the transModel to the array with specific index.
      transModels[i] = tt;
}

// now you have the array properly populated.
ListView lview = (ListView) view.findViewById(R.id.list_trans);
lview.setAdapter(new Mylistadapter(transModels));

动态添加元素到类

1 个答案: