Apex中文手册

for循环是一种重复控制结构，它允许您有效地编写需要执行特定次数的循环。 考虑一个业务案例，当我们想一次性处理或更新100条记录。 没有循环语法，这将是困难的。

语法：

for (variable : list_or_set) { code_block }

流程图：

示例：

考虑我们有一个Invoice对象，它存储CreatedDate，Status等日常发票的各种信息。在这个例子中，我们将获取今天创建的发票，状态为付费。

注意：在执行此示例之前，在“发票对象”中创建至少一个记录。

//Initializing the custom object records list to store the Invoice Records created today
List<apex_invoice__c> PaidInvoiceNumberList = new List<apex_invoice__c>();

//SOQL query which will fetch the invoice records which has been created today 
PaidInvoiceNumberList = [SELECT Id,Name, APEX_Status__c FROM APEX_Invoice__c  WHERE CreatedDate = today]; 

//List to store the Invoice Number of Paid invoices
List<string> InvoiceNumberList = new List<string>();

//This loop will iterate on the List PaidInvoiceNumberList and will process the each record
for (APEX_Invoice__c objInvoice: PaidInvoiceNumberList) {
	//Condition to check the current record in context values 
	if (objInvoice.APEX_Status__c == 'Paid') {
		//current record on which loop is iterating 
		System.debug('Value of Current Record on which Loop is iterating is '+objInvoice);
		//if Status value is paid then it will the invoice number into List of String
		InvoiceNumberList.add(objInvoice.Name);
	}
}
System.debug('Value of InvoiceNumberList '+InvoiceNumberList);