如何在不使用ArrayList的情况下编辑数组？ [英] How do I edit an array without using ArrayList?

问题描述

我已经设法将表的内容读入一个数组，但我现在有了删除行和更新单个元素的美好任务。



我明白，在Java中，Arrays被设置为一个特定的维度（这个是从while-nested-for循环中的ResultSet填充的），这使得删除变得困难。



填充数组的代码如下：

I have managed to read the contents of the table into an array, but I now have the oh-so joyous task of deleting rows and updating individual elements.

I understand that, in Java, Arrays are set to a specific dimension (this one is populated from a ResultSet in a while-nested-for loop), making deletion difficult.

The code I have for populating the array is as follows:

public static String[][] dbTable() throws SQLException
	{
		String[][] dbTable = null;
		table = conn.createStatement();
		String sql = "select * from Profiles";
		ResultSet rs = table.executeQuery(sql);
		rs.last();
		int rowNumb = rs.getRow();
		ResultSetMetaData rsmd = rs.getMetaData();
		int columnS = rsmd.getColumnCount();

		rs.beforeFirst();
		dbTable= new String[rowNumb][columnS];
		
		int i=0;
		while(rs.next() && i<rowNumb && rowNumb<100)
		{
			for(int j=0;j<columnS;j++)
			{
				dbTable[i][j] = rs.getString(j+1);
			}
			i++;
		}
		return dbTable;
	}

我需要应用程序处理SQL风格，所以我的应用程序可以说：

如果< insert method =here =>包含< string input =>删除匹配或说不存在的行。有一个问题（到目前为止）：这可能不使用ArrayLists吗？

I need the application to work on a SQL-style, so my application can say:
If <insert method="" here=""> contains <string input=""> remove the row that matches or says doesn't exist. There's one catch (so far): Is this possible without the use of ArrayLists?

推荐答案

这取决于你的编辑是什么意思。您可以通过索引编辑数组元素立即访问它，但是您需要一些集合来添加/插入/删除元素。



请阅读这篇好文章： http://www.cforcoding.com/2009/12/mutability-arrays-and -cost-of-temporary.html [ ^ ]。



基本上，不要将数组复制到集合中并返回。仅在最后创建一个数组，当您已经知道不需要修改它时。使用不可变集合是个好主意。原则上，你可以完全摆脱阵列，在许多情况下这是一个可行的决定。

-SA

It depends on what do you mean by "edit". You can edit array element immediately accessing it by index, but you will need some collection to add/insert/remove element.

Please read this nice article: http://www.cforcoding.com/2009/12/mutability-arrays-and-cost-of-temporary.html[^].

Basically, don't copy an array to collection and back. Create an array only at the very end, when you already know that you won't need to modify it. Using immutable collection is a good idea. In principle, you can get rid of arrays totally, which can be a viable decision in many cases.

—SA

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