Java的String.valueOf(String)和String a + "" 的效率

「爱情、让人受尽委屈。」 2022-03-29 01:58 416阅读 0赞

float a= 125F; 那么String s = ""; s = String.valueOf(a);   和   String s = "";  s = a + "";  哪个效率更高呢？今天做个测试和查看各种文章，好像有点头绪。循环n次方的时候，得出时间：

上代码：

public class Test0107 {
    
    	@Test
    	public void test() {
    		  float a = 123F;
    	        String s = "";
    	        int loopCount = 2000_0000;
    
    	        long start = System.currentTimeMillis();
    	        for (int i = 0; i < loopCount; i++) {
    	            s = String.valueOf(a);
    	            s = String.valueOf(a);
    	        }
    	        long end = System.currentTimeMillis();
    	        System.out.println("String.valueOf:" +(end - start));
    
    
    	        long start1 = System.currentTimeMillis();
    	        for (int i = 0; i < loopCount; i++) {
    	            s = a + "";
    	            s = a + "";
    	        }
    	        long end1 = System.currentTimeMillis();
    	        System.out.println("s = a + '' :" +(end1 - start1));
    
    	}
    }

运行结果：答案是String.valueOf(float)更快。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM2NDExODc0_size_16_color_FFFFFF_t_70][]

关于效率：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM2NDExODc0_size_16_color_FFFFFF_t_70 1][]

原因参考贴吧链接：[https://bbs.csdn.net/topics/390837088][https_bbs.csdn.net_topics_390837088]

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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM2NDExODc0_size_16_color_FFFFFF_t_70 1]: /images/20220329/a4d201babb28420998ce8f6216b31ede.png
[https_bbs.csdn.net_topics_390837088]: https://bbs.csdn.net/topics/390837088