{"id":68389,"date":"2019-08-26T11:09:37","date_gmt":"2019-08-26T03:09:37","guid":{"rendered":"http:\/\/www.xiaoyebailong.com\/?p=68389"},"modified":"2019-08-26T11:09:39","modified_gmt":"2019-08-26T03:09:39","slug":"java%e5%8f%96%e6%95%b4%e5%92%8cjava%e5%9b%9b%e8%88%8d%e4%ba%94%e5%85%a5%e6%96%b9%e6%b3%95","status":"publish","type":"post","link":"http:\/\/www.xiaoyebailong.com\/index.php\/2019\/08\/26\/68389.htm","title":{"rendered":"java\u53d6\u6574\u548cjava\u56db\u820d\u4e94\u5165\u65b9\u6cd5"},"content":{"rendered":"\n

import java.math.BigDecimal; 
import java.text.DecimalFormat;<\/p>\n\n\n\n

public class TestGetInt{ 
public static void main(String[] args){ 
   double i=2, j=2.1, k=2.5, m=2.9; 
   System.out.println(“\u820d\u6389\u5c0f\u6570\u53d6\u6574:Math.floor(2)=” + (int)Math.floor(i)); 
   System.out.println(“\u820d\u6389\u5c0f\u6570\u53d6\u6574:Math.floor(2.1)=” + (int)Math.floor(j)); 
   System.out.println(“\u820d\u6389\u5c0f\u6570\u53d6\u6574:Math.floor(2.5)=” + (int)Math.floor(k)); 
   System.out.println(“\u820d\u6389\u5c0f\u6570\u53d6\u6574:Math.floor(2.9)=” + (int)Math.floor(m)); 
                                        
   \/* \u8fd9\u6bb5\u88ab\u6ce8\u91ca\u7684\u4ee3\u7801\u4e0d\u80fd\u6b63\u786e\u7684\u5b9e\u73b0\u56db\u820d\u4e94\u5165\u53d6\u6574 
   System.out.println(“\u56db\u820d\u4e94\u5165\u53d6\u6574:Math.rint(2)=” + (int)Math.rint(i)); 
   System.out.println(“\u56db\u820d\u4e94\u5165\u53d6\u6574:Math.rint(2.1)=” + (int)Math.rint(j)); 
   System.out.println(“\u56db\u820d\u4e94\u5165\u53d6\u6574:Math.rint(2.5)=” + (int)Math.rint(k)); 
   System.out.println(“\u56db\u820d\u4e94\u5165\u53d6\u6574:Math.rint(2.9)=” + (int)Math.rint(m)); 
   
   System.out.println(“\u56db\u820d\u4e94\u5165\u53d6\u6574:(2)=” + new DecimalFormat(“0”).format(i)); 
   System.out.println(“\u56db\u820d\u4e94\u5165\u53d6\u6574:(2.1)=” + new DecimalFormat(“0”).format(i)); 
   System.out.println(“\u56db\u820d\u4e94\u5165\u53d6\u6574:(2.5)=” + new DecimalFormat(“0”).format(i)); 
   System.out.println(“\u56db\u820d\u4e94\u5165\u53d6\u6574:(2.9)=” + new DecimalFormat(“0”).format(i)); 
   *\/ 
   
   System.out.println(“\u56db\u820d\u4e94\u5165\u53d6\u6574:(2)=” + new BigDecimal(“2”).setScale(0, BigDecimal.ROUND_HALF_UP)); 
   System.out.println(“\u56db\u820d\u4e94\u5165\u53d6\u6574:(2.1)=” + new BigDecimal(“2.1”).setScale(0, BigDecimal.ROUND_HALF_UP)); 
   System.out.println(“\u56db\u820d\u4e94\u5165\u53d6\u6574:(2.5)=” + new BigDecimal(“2.5”).setScale(0, BigDecimal.ROUND_HALF_UP)); 
   System.out.println(“\u56db\u820d\u4e94\u5165\u53d6\u6574:(2.9)=” + new BigDecimal(“2.9”).setScale(0, BigDecimal.ROUND_HALF_UP));<\/p>\n\n\n\n

   System.out.println(“\u51d1\u6574:Math.ceil(2)=” + (int)Math.ceil(i)); 
   System.out.println(“\u51d1\u6574:Math.ceil(2.1)=” + (int)Math.ceil(j)); 
   System.out.println(“\u51d1\u6574:Math.ceil(2.5)=” + (int)Math.ceil(k)); 
   System.out.println(“\u51d1\u6574:Math.ceil(2.9)=” + (int)Math.ceil(m));<\/p>\n\n\n\n

   System.out.println(“\u820d\u6389\u5c0f\u6570\u53d6\u6574:Math.floor(-2)=” + (int)Math.floor(-i)); 
   System.out.println(“\u820d\u6389\u5c0f\u6570\u53d6\u6574:Math.floor(-2.1)=” + (int)Math.floor(-j)); 
   System.out.println(“\u820d\u6389\u5c0f\u6570\u53d6\u6574:Math.floor(-2.5)=” + (int)Math.floor(-k)); 
   System.out.println(“\u820d\u6389\u5c0f\u6570\u53d6\u6574:Math.floor(-2.9)=” + (int)Math.floor(-m)); 
   
   System.out.println(“\u56db\u820d\u4e94\u5165\u53d6\u6574:(-2)=” + new BigDecimal(“-2”).setScale(0, BigDecimal.ROUND_HALF_UP)); 
   System.out.println(“\u56db\u820d\u4e94\u5165\u53d6\u6574:(-2.1)=” + new BigDecimal(“-2.1”).setScale(0, BigDecimal.ROUND_HALF_UP)); 
   System.out.println(“\u56db\u820d\u4e94\u5165\u53d6\u6574:(-2.5)=” + new BigDecimal(“-2.5”).setScale(0, BigDecimal.ROUND_HALF_UP)); 
   System.out.println(“\u56db\u820d\u4e94\u5165\u53d6\u6574:(-2.9)=” + new BigDecimal(“-2.9”).setScale(0, BigDecimal.ROUND_HALF_UP));<\/p>\n\n\n\n

   System.out.println(“\u51d1\u6574:Math.ceil(-2)=” + (int)Math.ceil(-i)); 
   System.out.println(“\u51d1\u6574:Math.ceil(-2.1)=” + (int)Math.ceil(-j)); 
   System.out.println(“\u51d1\u6574:Math.ceil(-2.5)=” + (int)Math.ceil(-k)); 
   System.out.println(“\u51d1\u6574:Math.ceil(-2.9)=” + (int)Math.ceil(-m)); 
   } 
}<\/p>\n\n\n\n

\/\/_____________________________<\/p>\n\n\n\n

\u820d\u6389\u5c0f?\u53d6\u6574:Math.floor(2)=2
\u820d\u6389\u5c0f?\u53d6\u6574:Math.floor(2.1)=2
\u820d\u6389\u5c0f?\u53d6\u6574:Math.floor(2.5)=2
\u820d\u6389\u5c0f?\u53d6\u6574:Math.floor(2.9)=2
\u56db\u820d\u4e94\u5165\u53d6\u6574:(2)=2
\u56db\u820d\u4e94\u5165\u53d6\u6574:(2.1)=2
\u56db\u820d\u4e94\u5165\u53d6\u6574:(2.5)=3
\u56db\u820d\u4e94\u5165\u53d6\u6574:(2.9)=3
?\u6574:Math.ceil(2)=2
?\u6574:Math.ceil(2.1)=3
?\u6574:Math.ceil(2.5)=3
?\u6574:Math.ceil(2.9)=3
\u820d\u6389\u5c0f?\u53d6\u6574:Math.floor(-2)=-2
\u820d\u6389\u5c0f?\u53d6\u6574:Math.floor(-2.1)=-3
\u820d\u6389\u5c0f?\u53d6\u6574:Math.floor(-2.5)=-3
\u820d\u6389\u5c0f?\u53d6\u6574:Math.floor(-2.9)=-3
\u56db\u820d\u4e94\u5165\u53d6\u6574:(-2)=-2
\u56db\u820d\u4e94\u5165\u53d6\u6574:(-2.1)=-2
\u56db\u820d\u4e94\u5165\u53d6\u6574:(-2.5)=-3
\u56db\u820d\u4e94\u5165\u53d6\u6574:(-2.9)=-3
?\u6574:Math.ceil(-2)=-2
?\u6574:Math.ceil(-2.1)=-2
?\u6574:Math.ceil(-2.5)=-2
?\u6574:Math.ceil(-2.9)=-2<\/p>\n\n\n\n

===================================================<\/p>\n\n\n\n

        BigDecimal b = new BigDecimal(9.655 );
        \/\/double f1 = b.setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue();
        double f1 = b.setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue();<\/p>\n\n\n\n

        System.out.println(“f1=” + f1);\/\/f1=9.65
        BigDecimal mData = new BigDecimal(“9.655”).setScale(2, BigDecimal.ROUND_HALF_UP);
        System.out.println(“mData=” + mData);\/\/mData=9.66<\/p>\n\n\n\n

public BigDecimal<\/strong>(double val)<\/pre>\n\n\n\n
\u5c06 double \u8f6c\u6362\u4e3a BigDecimal\uff0c\u540e\u8005\u662f double \u7684\u4e8c\u8fdb\u5236\u6d6e\u70b9\u503c\u51c6\u786e\u7684\u5341\u8fdb\u5236\u8868\u793a\u5f62\u5f0f\u3002\u8fd4\u56de\u7684 BigDecimal \u7684\u6807\u5ea6\u662f\u4f7f (10scale<\/sup> \u00d7 val)\u4e3a\u6574\u6570\u7684\u6700\u5c0f\u503c\u3002<\/p>\n\n\n\n
\u6ce8\uff1a<\/strong><\/p>\n\n\n\n
  1. \u6b64\u6784\u9020\u65b9\u6cd5\u7684\u7ed3\u679c\u6709\u4e00\u5b9a\u7684\u4e0d\u53ef\u9884\u77e5\u6027\u3002\u6709\u4eba\u53ef\u80fd\u8ba4\u4e3a\u5728 Java \u4e2d\u5199\u5165\u00a0new BigDecimal(0.1)\u00a0\u6240\u521b\u5efa\u7684\u00a0BigDecimal\u00a0\u6b63\u597d\u7b49\u4e8e 0.1\uff08\u975e\u6807\u5ea6\u503c 1\uff0c\u5176\u6807\u5ea6\u4e3a 1\uff09\uff0c\u4f46\u662f\u5b83\u5b9e\u9645\u4e0a\u7b49\u4e8e 0.1000000000000000055511151231257827021181583404541015625\u3002\u8fd9\u662f\u56e0\u4e3a 0.1 \u65e0\u6cd5\u51c6\u786e\u5730\u8868\u793a\u4e3a\u00a0double\uff08\u6216\u8005\u8bf4\u5bf9\u4e8e\u8be5\u60c5\u51b5\uff0c\u4e0d\u80fd\u8868\u793a\u4e3a\u4efb\u4f55\u6709\u9650\u957f\u5ea6\u7684\u4e8c\u8fdb\u5236\u5c0f\u6570\uff09\u3002\u8fd9\u6837\uff0c\u4f20\u5165<\/em>\u5230\u6784\u9020\u65b9\u6cd5\u7684\u503c\u4e0d\u4f1a\u6b63\u597d\u7b49\u4e8e 0.1\uff08\u867d\u7136\u8868\u9762\u4e0a\u7b49\u4e8e\u8be5\u503c\uff09\u3002<\/li>
  2. \u53e6\u4e00\u65b9\u9762\uff0cString\u00a0\u6784\u9020\u65b9\u6cd5\u662f\u5b8c\u5168\u53ef\u9884\u77e5\u7684\uff1a\u5199\u5165\u00a0new BigDecimal(“0.1”)\u00a0\u5c06\u521b\u5efa\u4e00\u4e2a\u00a0BigDecimal\uff0c\u5b83\u6b63\u597d<\/em>\u00a0\u7b49\u4e8e\u9884\u671f\u7684 0.1\u3002\u56e0\u6b64\uff0c\u6bd4\u8f83\u800c\u8a00\uff0c\u901a\u5e38\u5efa\u8bae\u4f18\u5148\u4f7f\u7528\u00a0String\u00a0\u6784\u9020\u65b9\u6cd5\u3002<\/li>
  3. \u5f53\u00a0double\u00a0\u5fc5\u987b\u7528\u4f5c\u00a0BigDecimal\u00a0\u7684\u6e90\u65f6\uff0c\u8bf7\u6ce8\u610f\uff0c\u6b64\u6784\u9020\u65b9\u6cd5\u63d0\u4f9b\u4e86\u4e00\u4e2a\u51c6\u786e\u8f6c\u6362\uff1b\u5b83\u4e0d\u63d0\u4f9b\u4e0e\u4ee5\u4e0b\u64cd\u4f5c\u76f8\u540c\u7684\u7ed3\u679c\uff1a\u5148\u4f7f\u7528\u00a0Double.toString(double<\/code>)<\/code><\/a>\u00a0\u65b9\u6cd5\uff0c\u7136\u540e\u4f7f\u7528\u00a0BigDecimal(String)<\/code><\/a>\u00a0\u6784\u9020\u65b9\u6cd5\uff0c\u5c06\u00a0double\u00a0\u8f6c\u6362\u4e3a\u00a0String\u3002\u8981\u83b7\u53d6\u8be5\u7ed3\u679c\uff0c\u8bf7\u4f7f\u7528\u00a0static\u00a0valueOf(double)<\/code><\/a>\u00a0\u65b9\u6cd5\u3002<\/li><\/ol>\n","protected":false},"excerpt":{"rendered":"
    import java.math.BigDecimal; import java.text.DecimalFormat; public class TestGetInt{ public static void main(…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"topic":[],"class_list":["post-68389","post","type-post","status-publish","format-standard","hentry","category-technology"],"_links":{"self":[{"href":"http:\/\/www.xiaoyebailong.com\/index.php\/wp-json\/wp\/v2\/posts\/68389","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.xiaoyebailong.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.xiaoyebailong.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.xiaoyebailong.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.xiaoyebailong.com\/index.php\/wp-json\/wp\/v2\/comments?post=68389"}],"version-history":[{"count":1,"href":"http:\/\/www.xiaoyebailong.com\/index.php\/wp-json\/wp\/v2\/posts\/68389\/revisions"}],"predecessor-version":[{"id":68390,"href":"http:\/\/www.xiaoyebailong.com\/index.php\/wp-json\/wp\/v2\/posts\/68389\/revisions\/68390"}],"wp:attachment":[{"href":"http:\/\/www.xiaoyebailong.com\/index.php\/wp-json\/wp\/v2\/media?parent=68389"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.xiaoyebailong.com\/index.php\/wp-json\/wp\/v2\/categories?post=68389"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.xiaoyebailong.com\/index.php\/wp-json\/wp\/v2\/tags?post=68389"},{"taxonomy":"topic","embeddable":true,"href":"http:\/\/www.xiaoyebailong.com\/index.php\/wp-json\/wp\/v2\/topic?post=68389"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}