38 lines
1.2 KiB
Java
38 lines
1.2 KiB
Java
package com.inmind.system06;
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import java.time.Instant;
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import java.time.LocalDateTime;
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import java.util.Date;
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/*
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System类获取当前系统时刻
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static long currentTimeMillis() 返回当前时间（以毫秒为单位）。
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作用：以毫秒级别测试一段代码的执行效率，Instant以纳秒级别测试代码的执行效率
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*/
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public class SystemDemo15 {
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public static void main(String[] args) {
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// 获取当前时间
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Date date = new Date();
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long now2 = System.currentTimeMillis();
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LocalDateTime now = LocalDateTime.now();
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Instant now1 = Instant.now();
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System.out.println(date);
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System.out.println(date.getTime());
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System.out.println(now1.getNano());
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System.out.println(now2);
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System.out.println("------------以毫秒级别测试一段代码的执行效率------------");
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long start = System.currentTimeMillis();
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//测试500次打印消耗的时间（毫秒级）
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for (int i = 0; i < 500; i++) {
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System.out.println(i);
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}
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long end = System.currentTimeMillis();
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System.out.println("打印消耗的毫秒值："+(end-start));
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}
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}
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