public List getAllProduct(); //正確。定義返回類(lèi)型
public ArrayList getAllProduct(); //錯(cuò)誤！！定義返回類(lèi)型
public List queryByCritical(Map criticals); //定義參數(shù)類(lèi)型
public List queryByCritical(HashMap criticals); //錯(cuò)誤！！定義參數(shù)類(lèi)型

List result = null;//定義類(lèi)型的時(shí)候未List
result = new ArrayList();//只有構(gòu)造時(shí)出現(xiàn)的實(shí)現(xiàn)類(lèi)

Map result = null;//定義類(lèi)型的時(shí)候未Map
result = new HashMap();//只有構(gòu)造時(shí)出現(xiàn)的實(shí)現(xiàn)類(lèi)

String user_name= null;//錯(cuò)誤！！！ 即使數(shù)據(jù)庫(kù)中這種風(fēng)格
String userName = null;//正確寫(xiě)法
int CET_SIX=6;//常量命名時(shí)用下劃線區(qū)分單詞,字符全部大寫(xiě)

//錯(cuò)誤！！不能出現(xiàn)如此寫(xiě)法，需要定義為常量if(user.getNumber() == 1001 ) {
//do something
}
//正確寫(xiě)法static?final?int ADMINISTRATOR_ROLE_NUMBER = 1001;
static?final?int MIN_WIDTH = 4;
static?final?int MAX_WIDTH = 999;
static?final?int GET_THE_CPU = 1

if(user.getNumber() == ADMINISTRATOR_ROLE_NUMBER ) {
//do something
}

//sample code snippetfor(int i=0;i<10;i++){
    ValueObject vo = new ValueObject();
}

//recommend this style
ValueObject vo = null;
for(int i=0;i<10;i++){
   vo = new ValueObject();
}

//sample code snippetString sql =”INSERT INTO test (”;

Sql+=”column1,column2,values(”
Sql+=”1,2)”

StringBuffer sql = new?StringBuffer();
sql.append(”INSERT INTO test (”);
sql.appdend(”column1,column2,values(”);
sql.append(”1,2)”);

if ( condition) //single statement, code here
while ( condition ) //single statement, code here

//IFif ( condition) {
  //code here
}

//WHILEwhile ( condition ) {
  // code here
}

if ( foo ) {
    // code here
}

try {
    // code here
} catch (Exception bar) {
    // code here
} finally {
    // code here
}

while ( true ) {
    // code here
}

System.out.println(" debug 信息");

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

private?static Log logger = LogFactory.getLog(SQLTable.class);

logger.debug("debug 信息"); //注意這里沒(méi)有涉及字符串操作
    //涉及字符串操作或者方法調(diào)用的，需要用
    logger.isDebugEnable()
    來(lái)做判斷
    if(logger.isDebugEnable()){
       logger.debug(String1  + string 2 + string3 + object.callMethod()); 
}

logger.info(""Can't find column to build index. ColName=" + columnName");

try{
   //handle something
} catch (Exception ex) {
   //do nothing. 請(qǐng)確定該exception是否可以被忽略！！！！
}

try{
   //handle something
} catch (Exception ex) {
  ex.printStackTrace ();//不在程序中出現(xiàn)如此寫(xiě)法！！
}

try{
   //handle something
} catch (Exception ex) {
  log.error(ex);//這樣將僅僅是輸出ex.getMessage(),不能輸出stacktrace
}

try{
   //handle something
} catch (Exception ex) {
   log.error("錯(cuò)誤描述",ex);//使用log4j做異常記錄
}

//sample code snippet
Connection con = null;
Statement st = null;
ResultSet rs = null;

try {
  con = JNDIUtils.getConnection();
  st = …
  rs = …
} finally {
        JDBCUtil.safeClose(rs);//close resultset ,it is optional
        JDBCUtil.safeClose(st);//close statement after close resultset, it is optional
        JDBCUtil.safeClose(con);//make sure release it right now
}

//sample code snippetString username = …
…
if(“mark”.equals(userName)){
	…
}

//recommend coding conventionimport java.util.HashMap;
import java.util.Map;
import java.util.List;

//import java.util.*; 
NOT!!//We can use eclipse,right click, choose Source -> Organize Imports
//hotkey：Ctrl+Shift+O

/**
 * $Id: $
 *          
 */

<?xml version="1.0" encoding="UTF-8"?><!--
$Id:$ 
-->

//sample code snippet//TODO issue: the data format, should be fixed

//user table中的該字段允許為null，使用時(shí)就需要去check，否則可能出現(xiàn)nullpoint exception
if(user.getDescription()!=null) {
  //do something
}

<input type="text" maxlength = "10" size="20"/>