如何在java-8中避免/处理更清晰，更安全的Optional
但Optional emptyOptional = Optional.empty();
emptyOptional.ifPresent(System.out::println);
if (emptyOptional.isPresent())
System.out.println(emptyOptional.get());
以外的类别：
java-8 function getLocation()
{
if (navigator.geolocation)
{
navigator.geolocation.getCurrentPosition(reverseGeoLookup);
}
else
{
x.innerHTML="Geolocation is not supported by this browser.";
}
}
function reverseGeoLookup(position) {
var lat = position.coords.latitude;
var lon = position.coords.longitude;
var txt;
var req = new XMLHttpRequest()
req.open("GET", "https://maps.googleapis.com/maps/api/geocode/json?latlng="+lat+","+lon+"&sensor=true", true)
req.onreadystatechange = function() {
if(req.readyState == 4) {
var result = JSON.parse(req.response).results
for(var i = 0, length = result.length; i < length; i++) {
for(var j = 0; j < result[i].address_components.length; j++) {
var component = result[i].address_components[j]
if(~component.types.indexOf("postal_code")) {
txt = component.long_name;
$.ajax({
url: "genMapXML.php",
type: "post",
data: { post_code: txt },
success: function(){
alert('success');
},
error: function(){
alert('failure');
}
});
document.getElementById("trace_location").innerHTML = txt;
return false;
}
}
}
}
}
req.send()
}
还有其他方法吗？
答案 0 :(得分：0)
在java 8中避免!= null语句的唯一功能是可选，如果你想使用不同的模式，你几乎没有选择：
此外，您可以在SOF中查看有关avoiding-null-statements
的答案