## Java\u57fa\u7840\uff1a
\n### 1. JDK \u548c JRE \u6709\u4ec0\u4e48\u533a\u522b\uff1f
\n\u9762\u5411\u4eba\u7fa4\u4e0d\u540c\uff1a<\/p>\n
JDK\u662f\u9762\u5411\u5f00\u53d1\u4eba\u5458\u4f7f\u7528\u7684SDK\u3002<\/p>\n
JRE\u662fJava Runtime Enviroment\u662f\u6307Java\u7684\u8fd0\u884c\u73af\u5883\uff0c\u662f\u9762\u5411Java\u7a0b\u5e8f\u7684\u4f7f\u7528\u8005\u3002<\/p>\n
\u91cd\u8981\u7a0b\u5ea6\u4e0d\u540c\uff1a<\/p>\n
JRE\u7684\u5730\u4f4d\u5c31\u8c61\u4e00\u53f0PC\u673a\u4e00\u6837\uff0c\u7f16\u5199\u7684Java\u7a0b\u5e8f\u5fc5\u987b\u8981JRE\u624d\u80fd\u8fd0\u884c\u3002\u53ea\u8981\u4f60\u7684\u7535\u8111\u5b89\u88c5\u4e86JRE\uff0c\u5c31\u53ef\u4ee5\u6b63\u786e\u8fd0\u884cJav a\u5e94\u7528\u7a0b\u5e8f\u3002<\/p>\n
\u5b89\u88c5\u4f4d\u7f6e\u4e0d\u540c\uff1a<\/p>\n
\u5982\u679c\u5b89\u88c5JDK\uff0c\u7535\u8111\u6709\u4e24\u5957JRE\uff0c\u4e00\u5957\u4f4d\u4e8e \\jre \u53e6\u5916\u4e00\u5957\u4f4d\u4e8e C:\\Program Files\\Java\\j2re1.4.1_01 \u76ee\u5f55\u4e0b\u3002<\/p>\n
\u5982\u679c\u5b89\u88c5JRE\uff0c\u4f1a\u5728 C:\\Program Files\\Java \u76ee\u5f55\u4e0b\u5b89\u88c5\u552f\u4e00\u7684\u4e00\u5957JRE\u3002<\/p>\n
### 2. Java \u4e2d\u64cd\u4f5c\u5b57\u7b26\u4e32\u90fd\u6709\u54ea\u4e9b\u7c7b\uff1f\u5b83\u4eec\u4e4b\u95f4\u6709\u4ec0\u4e48\u533a\u522b\uff1f
\n\u64cd\u4f5c\u5b57\u7b26\u4e32\u7684\u7c7b\u6709\uff1aString\u3001StringBuffer\u3001StringBuilder\u3002<\/p>\n
String \u548c StringBuffer\u3001StringBuilder \u7684\u533a\u522b\u5728\u4e8e String \u58f0\u660e\u7684\u662f\u4e0d\u53ef\u53d8\u7684\u5bf9\u8c61\uff0c\u6bcf\u6b21\u64cd\u4f5c\u90fd\u4f1a\u751f\u6210\u65b0\u7684 String \u5bf9\u8c61\uff0c\u7136\u540e\u5c06\u6307\u9488\u6307\u5411\u65b0\u7684 String \u5bf9\u8c61\uff0c\u800c StringBuffer\u3001StringBuilder \u53ef\u4ee5\u5728\u539f\u6709\u5bf9\u8c61\u7684\u57fa\u7840\u4e0a\u8fdb\u884c\u64cd\u4f5c\uff0c\u6240\u4ee5\u5728\u7ecf\u5e38\u6539\u53d8\u5b57\u7b26\u4e32\u5185\u5bb9\u7684\u60c5\u51b5\u4e0b\u6700\u597d\u4e0d\u8981\u4f7f\u7528 String\u3002<\/p>\n
StringBuffer \u548c StringBuilder \u6700\u5927\u7684\u533a\u522b\u5728\u4e8e\uff0cStringBuffer \u662f\u7ebf\u7a0b\u5b89\u5168\u7684\uff0c\u800c StringBuilder \u662f\u975e\u7ebf\u7a0b\u5b89\u5168\u7684\uff0c\u4f46 StringBuilder \u7684\u6027\u80fd\u5374\u9ad8\u4e8e StringBuffer\uff0c\u6240\u4ee5\u5728\u5355\u7ebf\u7a0b\u73af\u5883\u4e0b\u63a8\u8350\u4f7f\u7528 StringBuilder\uff0c\u591a\u7ebf\u7a0b\u73af\u5883\u4e0b\u63a8\u8350\u4f7f\u7528 StringBuffer\u3002<\/p>\n
### 3. String str=”i”\u4e0e String str=new String(“i”)\u4e00\u6837\u5417\uff1f
\n\u4e0d\u4e00\u6837\uff0c\u56e0\u4e3a\u5185\u5b58\u7684\u5206\u914d\u65b9\u5f0f\u4e0d\u4e00\u6837\u3002String str=”i”\u7684\u65b9\u5f0f\uff0cJava \u865a\u62df\u673a\u4f1a\u5c06\u5176\u5206\u914d\u5230\u5e38\u91cf\u6c60\u4e2d\uff1b\u800c String str=new String(“i”) \u5219\u4f1a\u88ab\u5206\u5230\u5806\u5185\u5b58\u4e2d\u3002
\n### 4. \u5982\u4f55\u5c06\u5b57\u7b26\u4e32\u53cd\u8f6c\uff1f
\n\u4f7f\u7528 StringBuilder \u6216\u8005 stringBuffer \u7684 reverse() \u65b9\u6cd5\u3002
\n### 5. String \u7c7b\u7684\u5e38\u7528\u65b9\u6cd5\u90fd\u6709\u90a3\u4e9b\uff1f
\nindexOf()\uff1a\u8fd4\u56de\u6307\u5b9a\u5b57\u7b26\u7684\u7d22\u5f15\u3002
\ncharAt()\uff1a\u8fd4\u56de\u6307\u5b9a\u7d22\u5f15\u5904\u7684\u5b57\u7b26\u3002
\nreplace()\uff1a\u5b57\u7b26\u4e32\u66ff\u6362\u3002
\ntrim()\uff1a\u53bb\u9664\u5b57\u7b26\u4e32\u4e24\u7aef\u7a7a\u767d\u3002
\nsplit()\uff1a\u5206\u5272\u5b57\u7b26\u4e32\uff0c\u8fd4\u56de\u4e00\u4e2a\u5206\u5272\u540e\u7684\u5b57\u7b26\u4e32\u6570\u7ec4\u3002
\ngetBytes()\uff1a\u8fd4\u56de\u5b57\u7b26\u4e32\u7684 byte \u7c7b\u578b\u6570\u7ec4\u3002
\nlength()\uff1a\u8fd4\u56de\u5b57\u7b26\u4e32\u957f\u5ea6\u3002
\ntoLowerCase()\uff1a\u5c06\u5b57\u7b26\u4e32\u8f6c\u6210\u5c0f\u5199\u5b57\u6bcd\u3002
\ntoUpperCase()\uff1a\u5c06\u5b57\u7b26\u4e32\u8f6c\u6210\u5927\u5199\u5b57\u7b26\u3002
\nsubstring()\uff1a\u622a\u53d6\u5b57\u7b26\u4e32\u3002
\nequals()\uff1a\u5b57\u7b26\u4e32\u6bd4\u8f83\u3002
\n### 6. \u666e\u901a\u7c7b\u548c\u62bd\u8c61\u7c7b\u6709\u54ea\u4e9b\u533a\u522b\uff1f
\n\u666e\u901a\u7c7b\u4e0d\u80fd\u5305\u542b\u62bd\u8c61\u65b9\u6cd5\uff0c\u62bd\u8c61\u7c7b\u53ef\u4ee5\u5305\u542b\u62bd\u8c61\u65b9\u6cd5\u3002
\n\u62bd\u8c61\u7c7b\u4e0d\u80fd\u76f4\u63a5\u5b9e\u4f8b\u5316\uff0c\u666e\u901a\u7c7b\u53ef\u4ee5\u76f4\u63a5\u5b9e\u4f8b\u5316\u3002
\n### 7. \u62bd\u8c61\u7c7b\u80fd\u4f7f\u7528 final \u4fee\u9970\u5417\uff1f
\n\u4e0d\u80fd\uff0c\u5b9a\u4e49\u62bd\u8c61\u7c7b\u5c31\u662f\u8ba9\u5176\u4ed6\u7c7b\u7ee7\u627f\u7684\uff0c\u5982\u679c\u5b9a\u4e49\u4e3a final \u8be5\u7c7b\u5c31\u4e0d\u80fd\u88ab\u7ee7\u627f\uff0c\u8fd9\u6837\u5f7c\u6b64\u5c31\u4f1a\u4ea7\u751f\u77db\u76fe\uff0c\u6240\u4ee5 final \u4e0d\u80fd\u4fee\u9970\u62bd\u8c61\u7c7b
\n### 8. \u63a5\u53e3\u548c\u62bd\u8c61\u7c7b\u6709\u4ec0\u4e48\u533a\u522b\uff1f
\n\u5b9e\u73b0\uff1a\u62bd\u8c61\u7c7b\u7684\u5b50\u7c7b\u4f7f\u7528 extends \u6765\u7ee7\u627f\uff1b\u63a5\u53e3\u5fc5\u987b\u4f7f\u7528 implements \u6765\u5b9e\u73b0\u63a5\u53e3\u3002
\n\u6784\u9020\u51fd\u6570\uff1a\u62bd\u8c61\u7c7b\u53ef\u4ee5\u6709\u6784\u9020\u51fd\u6570\uff1b\u63a5\u53e3\u4e0d\u80fd\u6709\u3002
\n\u5b9e\u73b0\u6570\u91cf\uff1a\u7c7b\u53ef\u4ee5\u5b9e\u73b0\u5f88\u591a\u4e2a\u63a5\u53e3\uff1b\u4f46\u662f\u53ea\u80fd\u7ee7\u627f\u4e00\u4e2a\u62bd\u8c61\u7c7b\u3002
\n\u8bbf\u95ee\u4fee\u9970\u7b26\uff1a\u63a5\u53e3\u4e2d\u7684\u65b9\u6cd5\u9ed8\u8ba4\u4f7f\u7528 public \u4fee\u9970\uff1b\u62bd\u8c61\u7c7b\u4e2d\u7684\u65b9\u6cd5\u53ef\u4ee5\u662f\u4efb\u610f\u8bbf\u95ee\u4fee\u9970\u7b26\u3002
\n### 9. Java \u4e2d\u7684 Math. round(-1. 5) \u7b49\u4e8e\u591a\u5c11\uff1f
\n\u7b49\u4e8e -1\uff0c\u56e0\u4e3a\u5728\u6570\u8f74\u4e0a\u53d6\u503c\u65f6\uff0c\u4e2d\u95f4\u503c\uff080.5\uff09\u5411\u53f3\u53d6\u6574\uff0c\u6240\u4ee5\u6b63 0.5 \u662f\u5f80\u4e0a\u53d6\u6574\uff0c\u8d1f 0.5 \u662f\u76f4\u63a5\u820d\u5f03\u3002
\n### 10. == \u548c equals \u7684\u533a\u522b\u662f\u4ec0\u4e48\uff1f
\n== \u5bf9\u4e8e\u57fa\u672c\u7c7b\u578b\u6765\u8bf4\u662f\u503c\u6bd4\u8f83\uff0c\u5bf9\u4e8e\u5f15\u7528\u7c7b\u578b\u6765\u8bf4\u662f\u6bd4\u8f83\u7684\u662f\u5f15\u7528\uff1b\u800c equals \u9ed8\u8ba4\u60c5\u51b5\u4e0b\u662f\u5f15\u7528\u6bd4\u8f83\uff0c\u53ea\u662f\u5f88\u591a\u7c7b\u91cd\u65b0\u4e86 equals \u65b9\u6cd5\uff0c\u6bd4\u5982 String\u3001Integer \u7b49\u628a\u5b83\u53d8\u6210\u4e86\u503c\u6bd4\u8f83\uff0c\u6240\u4ee5\u4e00\u822c\u60c5\u51b5\u4e0b equals \u6bd4\u8f83\u7684\u662f\u503c\u662f\u5426\u76f8\u7b49\u3002
\n### 11. \u4e24\u4e2a\u5bf9\u8c61\u7684 hashCode() \u76f8\u540c\uff0c\u5219 equals() \u4e5f\u4e00\u5b9a\u4e3a true\uff0c\u5bf9\u5417\uff1f
\n\u4e0d\u5bf9\uff0c\u4e24\u4e2a\u5bf9\u8c61\u7684 hashCode() \u76f8\u540c\uff0cequals() \u4e0d\u4e00\u5b9a true\u3002<\/p>\n
\u4ee3\u7801\u793a\u4f8b\uff1a
\n“`java
\nSysem. out. println(String. format(“str1\uff1a%d | str2\uff1a%d”, str1. hashCode(),str2. hashCode()));
\nSystem. out. println(str1. equals(str2));
\n“`
\n\u6267\u884c\u7684\u7ed3\u679c\uff1a
\n“`java
\nstr1\uff1a1179395 | str2\uff1a1179395
\n“`<\/p>\n
\u4ee3\u7801\u89e3\u8bfb\uff1a\u5f88\u663e\u7136\u201c\u901a\u8bdd\u201d\u548c\u201c\u91cd\u5730\u201d\u7684 hashCode() \u76f8\u540c\uff0c\u7136\u800c equals() \u5219\u4e3a false\uff0c\u56e0\u4e3a\u5728\u6563\u5217\u8868\u4e2d\uff0chashCode() \u76f8\u7b49\u5373\u4e24\u4e2a\u952e\u503c\u5bf9\u7684\u54c8\u5e0c\u503c\u76f8\u7b49\uff0c\u7136\u800c\u54c8\u5e0c\u503c\u76f8\u7b49\uff0c\u5e76\u4e0d\u4e00\u5b9a\u80fd\u5f97\u51fa\u952e\u503c\u5bf9\u76f8\u7b49\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
## Java\u57fa\u7840\uff1a ### 1. JDK \u548c JRE \u6709\u4ec0\u4e48\u533a\u522b\uff1f \u9762\u5411\u4eba\u7fa4\u4e0d\u540c\uff1a JDK\u662f\u9762\u5411\u5f00\u53d1\u4eba\u5458\u4f7f\u7528 […]<\/p>\n","protected":false},"author":8,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[99],"tags":[],"class_list":["post-7220","post","type-post","status-publish","format-standard","hentry","category-javabase"],"_links":{"self":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/7220","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/users\/8"}],"replies":[{"embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/comments?post=7220"}],"version-history":[{"count":1,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/7220\/revisions"}],"predecessor-version":[{"id":7221,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/7220\/revisions\/7221"}],"wp:attachment":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/media?parent=7220"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/categories?post=7220"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/tags?post=7220"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}