在java中,除了遵循if-else梯形图外,还有什么更好的选择?
情况:我正在检查文件名,文件名存储在名为在java中,除了遵循if-else梯形图外,还有什么更好的选择?,java,string,if-statement,optimization,Java,String,If Statement,Optimization,情况:我正在检查文件名,文件名存储在名为str的变量中,根据if语句中检查的条件,我正在设置名为mailType的变量的值 if(str.contains("template")) { if(str.contains("unsupported")) mailType="unsupported"; else if(str.
str
的变量中,根据if
语句中检查的条件,我正在设置名为mailType
的变量的值
if(str.contains("template"))
{
if(str.contains("unsupported"))
mailType="unsupported";
else
if(str.contains("final_result"))
mailType="final_result";
else
if(str.contains("process_success"))
mailType="Process Success";
else
if(str.contains("receive"))
mailType="Receive";
else
if(str.contains("sen"))
mailType="sent";
else
if(str.contains("welcome"))
mailType="welcome";
else
if(str.contains("manual"))
mailType="Manual";
}
else
if(str.contains("properties"))
{
if(str.contains("unsupported"))
mailType="unsupported";
else
if(str.contains("final_result"))
mailType="final_result";
else
if(str.contains("process_success"))
mailType="Process Success";
else
if(str.contains("receive"))
mailType="Receive";
else
if(str.contains("sen"))
mailType="sent";
else
if(str.contains("welcome"))
mailType="welcome";
else
if(str.contains("manual"))
mailType="Manual";
}
问题:在java中,有没有更好的方法来缩短我的代码并对内存友好?使用LinkedHashMap
:
然后以相同的方式迭代键:
for (Map.Entry<String, LinkedHashMap<String, String>> outerEntry : outerMapping.entrySet()) {
if (str.contains(outerEntry.getKey()) {
// Apply the iteration above, using outerEntry.getValue().
}
}
for(Map.Entry outerEntry:outerMapping.entrySet()){
if(str.contains(outerEntry.getKey()){
//使用outerEntry.getValue()应用上面的迭代。
}
}
首先,如果使用else if
而不是简单的else
,缩进会更少
if(str.contains("unsupported"))
mailType="unsupported";
else if(str.contains("final_result"))
mailType="final_result";
else if(str.contains("process_success"))
mailType="Process Success";
else if(str.contains("receive"))
mailType="Receive";
else if(str.contains("sen"))
mailType="sent";
else if(str.contains("welcome"))
mailType="welcome";
else if(str.contains("manual"))
mailType="Manual";
在您的特殊情况下,我建议尝试使用正则表达式来简化您的工作:
Pattern p = Pattern.compile("(unsupported|final_result|welcome)");
Matcher m = p.matcher(str);
if (m.matches()) {
mailType = m.group(1);
}
你说你觉得(我也会这么做)太复杂了。他建议的else if
可能是你的一个选择:
if (str.contains("template")) {
if (str.contains("unsupported"))
mailType = "unsupported";
else if (str.contains("final_result"))
mailType = "final_result";
else if (str.contains("process_success"))
mailType = "Process Success";
else if (str.contains("receive"))
mailType = "Receive";
else if (str.contains("sen"))
mailType = "sent";
else if (str.contains("welcome"))
mailType = "welcome";
else if (str.contains("manual"))
mailType = "Manual";
} else if (str.contains("properties")) {
if (str.contains("unsupported"))
mailType = "unsupported";
else if (str.contains("final_result"))
mailType = "final_result";
else if (str.contains("process_success"))
mailType = "Process Success";
else if (str.contains("receive"))
mailType = "Receive";
else if (str.contains("sen"))
mailType = "sent";
else if (str.contains("welcome"))
mailType = "welcome";
else if (str.contains("manual"))
mailType = "Manual";
}
或者更好的是,通过一致地使用{}:
if (str.contains("template")) {
if (str.contains("unsupported")) {
mailType = "unsupported";
} else if (str.contains("final_result")) {
mailType = "final_result";
} else if (str.contains("process_success")) {
mailType = "Process Success";
} else if (str.contains("receive")) {
mailType = "Receive";
} else if (str.contains("sen")) {
mailType = "sent";
} else if (str.contains("welcome")) {
mailType = "welcome";
} else if (str.contains("manual")) {
mailType = "Manual";
}
} else if (str.contains("properties")) {
if (str.contains("unsupported")) {
mailType = "unsupported";
} else if (str.contains("final_result")) {
mailType = "final_result";
} else if (str.contains("process_success")) {
mailType = "Process Success";
} else if (str.contains("receive")) {
mailType = "Receive";
} else if (str.contains("sen")) {
mailType = "sent";
} else if (str.contains("welcome")) {
mailType = "welcome";
} else if (str.contains("manual")) {
mailType = "Manual";
}
}
试试这个
static String containsAndValue(Collection<String> collection, String oldValue, String... strings) {
if (strings.length % 2 != 0)
throw new IllegalArgumentException("strings");
for (int i = 0; i < strings.length; i += 2)
if (collection.contains(strings[i]))
return strings[i + 1];
return oldValue;
}
这不那么复杂吗
public enum MailType {
UNSUPPORTED("unsupported", "unsupported"),
FINAL_RESULT("final_result", "final_result"),
PROCESS_SUCCESS("process_success", "Process Success"),
RECEIVE("receive", "Receive"),
SENT("sen", "sent"),
WELCOME("welcome", "welcome"),
MANUAL("manual", "Manual");
private final String query;
private final String value;
MailType(String query, String value) {
this.query = query;
this.value = value;
}
public static String find(String text){
for(MailType mailType: values()){
if(text.contains(mailType.query)) {
return mailType.value;
}
}
return null;
}
}
然后像这样使用它:
String mailType = MailType.find(str);
如果使用if-else
而不是else
(不带大括号),则代码的可读性会更好然后缩进后续的块。只是提出Andy的观点:或者更好@T.J.Crowder谢谢你添加这些!@T.J.Crowder有趣的是,没有正确格式的阶梯,答案变得很明显。无意冒犯,但我发现这种方法有点复杂,因为我是初学者,你能推荐其他方法吗?而且这种方法需要你选择的方法取决于你想要优化什么。这只是一种方法;我可以看到为什么你会认为它是初学者的复杂。如果你想动态地指定映射(例如,在外部配置中),这是非常好的;正如他们所说的,YMMV:@varunsinghal:以上内容只会占用少量内存,无需担心。它也很容易维护,而且一点也不复杂。FWIW,这就是我要做的,或者类似的事情。正则表达式方法不太管用-一些邮件类型与匹配的邮件类型不一样(例如process\u success
=>process success
)。是的,但至少它可以帮助删除一些if语句。在字符串处理的情况下,我尽量使用正则表达式,因为它是合适的工具。“我尽量使用正则表达式,因为它是合适的工具”你显然从未听说过引号:),我认为它并没有真正的帮助-然后你只需创建一个从“你发现的正则表达式”到相应值的映射。然后你基本上回到我的解决方案。
static String containsAndValue(Collection<String> collection, String oldValue, String... strings) {
if (strings.length % 2 != 0)
throw new IllegalArgumentException("strings");
for (int i = 0; i < strings.length; i += 2)
if (collection.contains(strings[i]))
return strings[i + 1];
return oldValue;
}
if (str.contains("template")) {
mailType = containsAndValue(str, mailType,
"unsupported", "unsupported",
"final_result", "final_result",
"process_success", "Process Success",
"receive", "Receive",
"sen", "sent",
"welcome", "welcome",
"manual", "Manual");
} else if (str.contains("properties")) {
mailType = containsAndValue(str, mailType,
"unsupported", "unsupported",
"final_result", "final_result",
"process_success", "Process Success",
"receive", "Receive",
"sen", "sent",
"welcome", "welcome",
"manual", "Manual");
}
public enum MailType {
UNSUPPORTED("unsupported", "unsupported"),
FINAL_RESULT("final_result", "final_result"),
PROCESS_SUCCESS("process_success", "Process Success"),
RECEIVE("receive", "Receive"),
SENT("sen", "sent"),
WELCOME("welcome", "welcome"),
MANUAL("manual", "Manual");
private final String query;
private final String value;
MailType(String query, String value) {
this.query = query;
this.value = value;
}
public static String find(String text){
for(MailType mailType: values()){
if(text.contains(mailType.query)) {
return mailType.value;
}
}
return null;
}
}
String mailType = MailType.find(str);