避免自動裝箱
阿新 • • 發佈：2017-11-08
class sta 基本類型 nbsp void stat art get pub
long sum1 = 0L;
for(int i = 0,max = 1000000; i < max; i++) {
sum1 += 5;
}
end = new Date();
System.out.println("用時: " + (end.getTime() - start.getTime()));
}
public class Person {
public static void main(String[] args) {
// TODO Auto-generated method stub
//較差
Date start = new Date();
Long sum = 0L;
for(int i = 0,max = 1000000; i < max; i++) {
sum += 5;
}
Date end = new Date();
System.out.println("用時: " + (end.getTime() - start.getTime()));
//較好
start = new
long sum1 = 0L;
for(int i = 0,max = 1000000; i < max; i++) {
sum1 += 5;
}
end = new Date();
System.out.println("用時: " + (end.getTime() - start.getTime()));
}
}
輸出結果:
用時: 18
用時: 2
要優先使用基本類型而不是裝箱基本類型,要當心無意識的自動裝箱
避免自動裝箱