問(wèn)題描述
我正在開(kāi)發(fā)一個(gè) Web 應(yīng)用程序，在該應(yīng)用程序中，數(shù)據(jù)將在客戶端和客戶端之間傳輸.服務(wù)器端.
I am working on a web application in which data will be transfer between client & server side.
我已經(jīng)知道 JavaScript int != Java int.因?yàn)椋琂ava int 不能為空，對(duì).現(xiàn)在這是我面臨的問(wèn)題.
I already know that JavaScript int != Java int. Because, Java int cannot be null, right. Now this is the problem I am facing.
我將我的 Java int 變量更改為 Integer.
I changed my Java int variables into Integer.
public void aouEmployee(Employee employee) throws SQLException, ClassNotFoundException
{
Integer tempID = employee.getId();
String tname = employee.getName();
Integer tage = employee.getAge();
String tdept = employee.getDept();
PreparedStatement pstmt;
Class.forName("com.mysql.jdbc.Driver");
String url ="jdbc:mysql://localhost:3306/general";
java.sql.Connection con = DriverManager.getConnection(url,"root", "1234");
System.out.println("URL: " + url);
System.out.println("Connection: " + con);
pstmt = (PreparedStatement) con.prepareStatement("REPLACE INTO PERSON SET ID=?, NAME=?, AGE=?, DEPT=?");
pstmt.setInt(1, tempID);
pstmt.setString(2, tname);
pstmt.setInt(3, tage);
pstmt.setString(4, tdept);
pstmt.executeUpdate();
}
我的問(wèn)題在這里:
pstmt.setInt(1, tempID);
pstmt.setInt(3, tage);
我不能在這里使用整數(shù)變量.我試過(guò) intgerObject.intValue();但它使事情變得更加復(fù)雜.我們還有其他轉(zhuǎn)換方法或轉(zhuǎn)換技術(shù)嗎?
I cant use the Integer variables here. I tried with intgerObject.intValue();
But it makes things more complex. Do we have any other conversion methods or conversion techniques?
任何修復(fù)都會(huì)更好.
推薦答案
正如已經(jīng)在別處寫(xiě)的:
- 對(duì)于 Java 1.5 及更高版本，您(幾乎)不需要做任何事情，它由編譯器完成.
- 對(duì)于 Java 1.4 及之前版本，使用
Integer.intValue()將 Integer 轉(zhuǎn)換為 int.
- For Java 1.5 and later you don't need to do (almost) anything, it's done by the compiler.
- For Java 1.4 and before, use
Integer.intValue()to convert from Integer to int.
但是正如您所寫(xiě)，Integer 可以為空，因此在嘗試轉(zhuǎn)換為 int 之前檢查一下是明智的(否則可能會(huì)遇到 NullPointerException).
BUT as you wrote, an Integer can be null, so it's wise to check that before trying to convert to int (or risk getting a NullPointerException).
pstmt.setInt(1, (tempID != null ? tempID : 0)); // Java 1.5 or later
或
pstmt.setInt(1, (tempID != null ? tempID.intValue() : 0)); // any version, no autoboxing
* 使用默認(rèn)值零，也可以什么都不做，顯示警告或...
我大多不喜歡使用自動(dòng)裝箱(第二個(gè)示例行)，所以很清楚我想要做什么.
I mostly prefer not using autoboxing (second sample line) so it's clear what I want to do.
這篇關(guān)于如何將整數(shù)轉(zhuǎn)換為整數(shù)?的文章就介紹到這了，希望我們推薦的答案對(duì)大家有所幫助，也希望大家多多支持html5模板網(wǎng)！