将while循环中的项目添加到ArrayList java
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Adding items from a while loop to an ArrayList java
提问by Calibre2010
Simple one here, I have connected to a sqldb and from my database I am retrieving rows from a table.
这里很简单，我已连接到 sqldb 并从我的数据库中检索表中的行。
For each row i wish to save the data to an ArrayList. Each row being an
item in the ArrayList.
对于每一行，我希望将数据保存到ArrayList. 每一行都是ArrayList.
This is what I have so far.
这就是我迄今为止所拥有的。
List<DVDProperty> DVDList = new ArrayList<DVDProperty>();
DVDProperty context = new DVDProperty();
while (res.next()) {
int i = res.getInt("idnew_table");
String s = res.getString("dvdName");
context.setDVDId(i);
context.setDVDName(s);
DVDList.add(context);
}
DVDProperyis a set property where i set the properties with the table row values.
DVDPropery是一个设置属性，我在其中使用表行值设置属性。
I have 2 rows with the following data
我有 2 行包含以下数据
1 Scarface
2 Avatar
1 疤面煞星
2 阿凡达
Everytime I Run through the loop my ArrayListoverrides
1 Scarface
with 2 Avatar twice
每次我运行循环时，我都会ArrayList用 2 个头像两次覆盖 1 Scarface
I wish to add a new row to my ArrayListeach time
and it not override
我希望ArrayList每次都添加一个新行，而不是覆盖
回答by Bozho
Instantiate DVDPropertyinside the loop. Currently you are reusing the same instance, and thus overriding its properties:
DVDProperty在循环内实例化。目前您正在重用同一个实例，从而覆盖其属性：
while (res.next()) {
DVDProperty context = new DVDProperty();
...
}
回答by Karol Lewandowski
You have to create new object of type DVDProperty for every record. At this time you change the same object (context) in every iteration. Try:
您必须为每条记录创建类型为 DVDProperty 的新对象。此时，您在每次迭代中更改相同的对象（上下文）。尝试：
List<DVDProperty> DVDList = new ArrayList<DVDProperty>();
while (res.next()) {
int i = res.getInt("idnew_table");
String s = res.getString("dvdName");
DVDProperty context = new DVDProperty();
context.setDVDId(i);
context.setDVDName(s);
DVDList.add(context);
}
回答by karan shah
Please create new instance of the DVDProperty object in loop everytime it runs the loop.
Please refer to code snippet below.
Code
List<DVDProperty> DVDList = new ArrayList<DVDProperty>();
DVDProperty context = null;
while (res.next()) {
int i = res.getInt("idnew_table");
String s = res.getString("dvdName");
context = new DVDProperty();
context.setDVDId(i);
context.setDVDName(s);
DVDList.add(context);
}
