問題描述
我正在開發一個 Web 應用程序，在該應用程序中，數據將在客戶端和客戶端之間傳輸.服務器端.
I am working on a web application in which data will be transfer between client & server side.
我已經知道 JavaScript int != Java int.因為，Java int 不能為空，對.現在這是我面臨的問題.
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();
}
我的問題在這里:
pstmt.setInt(1, tempID);
pstmt.setInt(3, tage);
我不能在這里使用整數變量.我試過 intgerObject.intValue();但它使事情變得更加復雜.我們還有其他轉換方法或轉換技術嗎?
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?
任何修復都會更好.
推薦答案
正如已經在別處寫的:
- 對于 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.
- 對于 Java 1.4 及之前版本，使用
Integer.intValue()將 Integer 轉換為 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，Integer 可以為空，因此在嘗試轉換為 int 之前檢查一下是明智的(否則可能會遇到 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裝箱(第二個示例行)，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.
這篇關于如何將整數轉換為整數?的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網！