JDK8\uff08jdk 1.8\uff09\u7248\u672c\uff08\u76ee\u524d\u6700\u65b0\u5df2\u523017\uff09\n\n\u5b98\u65b9\u5730\u5740\uff1ahttps:\/\/www.oracle.com\/java\/technologies\/downloads\/#java8\n\u767e\u5ea6\u4e91\u76d8\uff1a\u8d44\u6e90\u76ee\u5f55<\/code><\/pre>\n\u5b89\u88c5\u597d\u4e4b\u540e\u9700\u8981\u914d\u7f6e\u4e0b\u73af\u5883\u53d8\u91cf\u3002<\/p>\n
![\"image-20210929163956511\"](\"https:\/\/lemon-guess.oss-cn-hangzhou.aliyuncs.com\/img\/image-20210929163956511.png\")
<\/p>\n
![\"image-20210929163410661\"](\"https:\/\/lemon-guess.oss-cn-hangzhou.aliyuncs.com\/img\/image-20210929163410661.png\")
<\/p>\n
\u5173\u4e8emac\u7cfb\u7edf\uff0c\u81ea\u5e26JDK\uff1a<\/p>\n
![\"image-20210929152514354\"](\"https:\/\/lemon-guess.oss-cn-hangzhou.aliyuncs.com\/img\/image-20210929152514354.png\")
<\/p>\n
\/Library\/Java\/JavaVirtualMachines <\/code><\/pre>\n![\"image-20210929152444076\"](\"https:\/\/lemon-guess.oss-cn-hangzhou.aliyuncs.com\/img\/image-20210929152444076.png\")
<\/p>\n
\u7f16\u5199\u4ee3\u7801+\u7f16\u8bd1+\u8fd0\u884c\uff1a<\/p>\n
\n- \n
\u7f16\u5199Java\u4ee3\u7801\uff1aHello.java<\/p>\n
public class Hello {\n public static void main(String[] args) {\n System.out.println(\"Hello World\");\n }\n}<\/code><\/pre>\n<\/li>\n- \n
\u6253\u5f00\u7ec8\u7aef\u53bb\u8fd0\u884c\u547d\u4ee4<\/p>\n
>>>javac Hello.java\n>>>java Hello<\/code><\/pre>\n<\/li>\n<\/ul>\n2.2 Inteliji<\/h3>\n
\u7f16\u5199Java\u4ee3\u7801\u65f6\u5efa\u8bae\u5927\u5bb6\u4f7f\u7528IDE\uff08\u96c6\u6210\u5f00\u53d1\u73af\u5883\uff09\u6765\u63d0\u4f9b\u5f00\u53d1\u6548\u7387\u3002<\/p>\n
\n- \n
\u4e0b\u8f7d\uff0c\u5efa\u8bae\u30102020.1.1\u7248\u672c\u3011<\/p>\n
https:\/\/www.jetbrains.com\/idea\/download\/other.html<\/code><\/pre>\n<\/li>\n- \n
\u6fc0\u6d3b<\/p>\n
\u89c6\u9891\uff1ahttps:\/\/www.zhihu.com\/zvideo\/1254435808801050624\n\u6fc0\u6d3b\u5305\uff1a\u5728\u7f51\u76d8\u5171\u4eab\u76ee\u5f55\uff0c\u5176\u4ed6\u5171\u4eab\u8d44\u6599\u5305\u6587\u4ef6\u5939\u3010jetbrains-agent-latest.zip\u3011<\/code><\/pre>\n<\/li>\n<\/ul>\n![\"image-20220127202943378\"](\"https:\/\/lemon-guess.oss-cn-hangzhou.aliyuncs.com\/img\/image-20220127202943378.png\")
<\/p>\n
2.3 Java\u57fa\u7840\u8bed\u6cd5<\/h3>\n
\u521d\u6b65\u4ee3\u7801\u7684\u5206\u6790\uff1aHello.java<\/code><\/p>\npublic class Hello {\n public static void main(String[] args) {\n System.out.println("\u4f60\u597d\u5440");\n }\n}<\/code><\/pre>\n\n- \n
\u4e3b\u51fd\u6570 & \u7a0b\u5e8f\u7684\u5165\u53e3\u3002<\/p>\n
def func():\n pass\n\nif __name__ == \"__main__\":\nfunc()<\/code><\/pre>\n<\/li>\n- \n
\u6587\u4ef6\u540d<\/p>\n
\u4e00\u4e2a\u6587\u4ef6\u4e2d\u6700\u591a\u53ea\u80fd\u6709\u4e00\u4e2apublic\u7c7b \u4e14 \u6587\u4ef6\u540d\u5fc5\u987b\u548cpublic\u7c7b\u540d\u4e00\u81f4\u3002\n\u5982\u679c\u6587\u4ef6\u4e2d\u6709\u591a\u4e2a\u7c7b\uff0c\u6587\u4ef6\u540d\u4e0epublic\u7c7b\u540d\u4e00\u81f4\u3002\n\u5982\u679c\u6587\u4ef6\u4e2d\u6709\u591a\u4e2a\u7c7b \u4e14 \u65e0public\u7c7b\uff0c\u6587\u4ef6\u540d\u53ef\u4ee5\u662f\u4efb\u610f\u7c7b\u540d\u3002<\/code><\/pre>\n<\/li>\n- \n
\u7c7b\u540d<\/p>\n
\u9996\u5b57\u6bcd\u5927\u5199\u4e14\u9a7c\u5cf0\u5f0f\u547d\u540d\uff0c\u4f8b\u5982\uff1aHello\u3001UserInfo\u3001PersonApplication<\/code><\/pre>\n<\/li>\n- \n
\u7c7b\u4fee\u9970\u7b26\uff1apublic\u3001default\uff08\u4e0d\u5199\uff09<\/p>\n<\/li>\n
- \n
\u7c7b\u4e2d\u6210\u5458\u4fee\u9970\u7b26\uff1apublic\u3001private\u3001protected\u3001default\uff08\u4e0d\u5199\uff09<\/p>\n<\/li>\n
- \n
\u9759\u6001\u6210\u5458\uff0c\u65e0\u5e8f\u5b9e\u4f8b\u5316\u5c31\u53ef\u4ee5\u6307\u5b9a\u8c03\u7528\u3002<\/p>\n
class MyTest{\n\n public void f1(){\n System.out.println(\"f1\");\n }\n\n public static void f2(){\n System.out.println(\"f2\");\n }\n}\n\npublic class Hello {\n\n public static void main(String[] args) {\n \/\/1.\u5b9e\u4f8b\u5316\n MyTest obj = new MyTest();\n \/\/ 2.\u5bf9\u8c61\u8c03\u7528\n obj.f1();\n\n MyTest.f2();\n }\n}<\/code><\/pre>\nclass Person{\n public static void f1(){\n \/\/ \u9759\u6001\u65b9\u6cd5\n System.out.println(\"\u6211\u662fF1\u51fd\u6570\");\n }\n}\n\npublic class Hello {\n public static void main(String[] args) {\n Person.f1();\n }\n}<\/code><\/pre>\nclass Person {\n public void f2() {\n \/\/ \u5b9e\u4f8b\u65b9\u6cd5\n System.out.println(\"\u6211\u662fF1\u51fd\u6570\");\n }\n}\n\npublic class Hello {\n public static void main(String[] args) {\n \/\/ \u5b9e\u4f8b\u5316\u5bf9\u8c61 obj = Person();\n Person obj = new Person();\n\n \/\/ \u5bf9\u8c61\u8c03\u7528f2\n obj.f2();\n }\n}<\/code><\/pre>\n<\/li>\n- \n
void\u8868\u793a\u65b9\u6cd5\u6ca1\u6709\u8fd4\u56de\u503c<\/p>\n
class MyTest{\n\n public int f1(){\n System.out.println(\"f1\");\n\n return 123;\n }\n\n public static String f2(){\n System.out.println(\"f2\");\n return \"\u54c8\u54c8\u54c8\";\n }\n}\n\npublic class Hello {\n\n public static void main(String[] args) {\n\n MyTest obj = new MyTest();\n int v1 = obj.f1();\n\n String v2 = MyTest.f2();\n }\n}\n<\/code><\/pre>\n<\/li>\n- \n
\u53c2\u6570<\/p>\n
class MyTest {\n\n public int f1(int a1, int a2) {\n int result = a1 + a2;\n return result;\n }\n\n}\n\npublic class Hello {\n\n public static void main(String[] args) {\n MyTest obj = new MyTest();\n int v1 = obj.f1(1, 2);\n }\n}<\/code><\/pre>\n<\/li>\n<\/ul>\n\u8865\u5145\uff1a<\/strong><\/p>\nPython \u5b98\u65b9\u6e90\u4ee3\u7801\u4e0d\u4e5f\u6709java\u8fd9\u6837\u5199\u7684\u4e48\uff1f\n\ndef func(a1,a2):\n return a1 + a2\n\n# \u5efa\u8bae\ndef foo(a1: str a2:int) -> int\n return 1\n\nfoo(11,22)<\/code><\/pre>\n2.3.1 \u6ce8\u91ca<\/h4>\n\/**\n * \u5bf9\u8fd9\u4e2a\u7c7b\u8fdb\u884c\u6ce8\u91ca\n *\/\npublic class Hello {\n\n \/**\n * \u8fd9\u4e2a\u65b9\u6cd5\u662f\u5e72\u561b....\n * @param v1 \u5927\u5c0f\n * @param v2 \u5c3a\u5bf8\n * @return \u8fd4\u56de\u4e00\u4e2axxx\n *\/\n public static String getSign(int v1, String v2) {\n return "\u54c8\u54c8\u54c8";\n }\n\n public static void main(String[] args) {\n \/\/ \u5355\u884c\u6ce8\u91ca\n \/\/ int age = 18;\n\n \/* \u591a\u884c\u6ce8\u91ca\n String name = "\u6b66\u6c9b\u9f50";\n int size = 18;\n *\/\n }\n}<\/code><\/pre>\n\u6ce8\u610f\uff1aJavaScript<\/p>\n
2.3.2 \u53d8\u91cf\u548c\u5e38\u91cf<\/h4>\npublic class Hello {\n\n public static void main(String[] args) {\n String name = "\u6b66\u6c9b\u9f50";\n name = "alex";\n\n int age = 19;\n age = 20;\n\n final int size = 18;\n }\n}<\/code><\/pre>\nv1 = [111,22]\nv2 = 345<\/code><\/pre>\n2.3.3 \u8f93\u5165\u548c\u8f93\u51fa<\/h4>\nimport java.util.Scanner;\n\npublic class Hello {\n\n public static void main(String[] args) {\n \/\/ \u8f93\u5165\n Scanner input = new Scanner(System.in);\n String text = input.nextLine();\n\n \/\/ \u8f93\u51fa\n System.out.println(text);\n \/\/ System.out.print(text);\n }\n}<\/code><\/pre>\nimport java.util.Scanner;\n\npublic class Hello {\n\n public static void main(String[] args) {\n \/\/ \u8f93\u51fa\n System.out.print("\u8bf7\u8f93\u5165\uff1a");\n\n \/\/ \u8f93\u5165\n Scanner input = new Scanner(System.in);\n String text = input.nextLine();\n\n \/\/ \u8f93\u51fa\n System.out.println(text);\n }\n}<\/code><\/pre>\n2.3.4 \u6761\u4ef6\u8bed\u53e5<\/h4>\nimport java.util.Scanner;\n\npublic class Hello {\n\n public static void main(String[] args) {\n int age = 19;\n\n if (age < 18) {\n System.out.println("\u5c11\u5e74");\n } else if (age < 40) {\n System.out.println("\u5927\u53d4");\n } else {\n System.out.println("\u8001\u6c49");\n }\n\n }\n}<\/code><\/pre>\npublic class Hello {\n\n public static void main(String[] args) {\n int score = 19;\n\n switch (score) {\n case 10:\n System.out.println("xxx");\n System.out.println("xxx");\n System.out.println("xxx");\n break;\n case 20:\n System.out.println("xxx");\n System.out.println("xxx");\n System.out.println("xxx");\n break;\n default:\n System.out.println("xxx");\n break;\n }\n\n }\n}<\/code><\/pre>\n2.3.5 \u5faa\u73af\u8bed\u53e5<\/h4>\n
while\u5faa\u73af<\/p>\n
public class Hello {\n\n public static void main(String[] args) {\n\n int count = 0;\n while (count < 3) {\n System.out.println("\u6267\u884c\u4e2d...");\n count += 1;\n }\n }\n}<\/code><\/pre>\ndo while\u5faa\u73af\uff08\u81f3\u5c11\u6267\u884c1\u6b21\uff09<\/p>\n
public class Hello {\n public static void main(String[] args) {\n\n int count = 0;\n do {\n System.out.println("\u6267\u884c\u4e2d...");\n count += 1;\n } while (count < 3);\n\n }\n}<\/code><\/pre>\nfor\u5faa\u73af<\/p>\n
public class Hello {\n\n public static void main(String[] args) {\n\n for (int i = 0; i < 10; i++) {\n System.out.println("\u54c8\u54c8\u54c8");\n }\n\n }\n}<\/code><\/pre>\npublic class Hello {\n\n public static void main(String[] args) {\n\n String[] nameList = {"\u4fee\u4ed9", "\u8096\u5cf0", "\u9ebb\u5b50", "\u5341\u5206"};\n \/\/ nameList.length 4\n \/\/ nameList[0]\n\n for (int idx = 0; idx < nameList.length; idx++) {\n String ele = nameList[idx];\n System.out.println(ele);\n }\n }\n}<\/code><\/pre>\n\u6ce8\u610f\uff1a\u4e5f\u652f\u6301break\/continue\u3002<\/p>\n
2.4 \u6570\u636e\u7c7b\u578b<\/h3>\n2.4.1 \u6574\u6570\u7c7b\u578b<\/h4>\n\n- byte\uff0c\u5b57\u8282 \u30101\u5b57\u8282\u3011\u8868\u793a\u8303\u56f4\uff1a-128 ~ 127 \u5373\uff1a
-2^7 ~ 2^7 -1 <\/code> <\/li>\n- short\uff0c\u77ed\u6574\u578b \u30102\u5b57\u8282\u3011\u8868\u793a\u8303\u56f4\uff1a-32768 ~ 32767<\/li>\n
- int\uff0c\u6574\u578b \u30104\u5b57\u8282\u3011\u8868\u793a\u8303\u56f4\uff1a-2147483648 ~ 2147483647<\/li>\n
- long\uff0c\u957f\u6574\u578b \u30108\u5b57\u8282\u3011\u8868\u793a\u8303\u56f4\uff1a-9223372036854775808 ~ 9223372036854775807<\/li>\n<\/ul>\n
public class Hello {\n\n public static void main(String[] args) {\n byte v1 = 32;\n short v2 = 10000;\n int v3 = 22221331;\n long v4 = 554534353424L;\n }\n}<\/code><\/pre>\n\u63d0\u9192\uff1a<\/strong>\u9006\u5411\u65f6\u6709\u4e00\u4e9b\u5b57\u7b26\u4e32\u662f\u901a\u8fc7\u5b57\u8282\u6570\u7ec4\u6765\u8868\u793a\uff08UTF-8\u7f16\u7801\uff09<\/p>\nv1 = "\u6b66\u6c9b\u9f50"\nv2 = [230, 173, 166, 230, 178, 155, 233, 189, 144]\n<\/code><\/pre>\nimport java.util.Arrays;\n\npublic class Hello {\n\n public static void main(String[] args) {\n \/\/ 1.\u5b57\u8282\u6570\u7ec4\uff08\u8f6c\u6362\u4e3a\u5b57\u7b26\u4e32\uff09 [\u5b57\u8282,\u5b57\u8282,\u5b57\u8282]\n byte[] dataList = {97, 105, 100, 61, 50, 52, 54, 51, 56, 55, 53, 55, 49, 38, 97, 117, 116, 111, 95, 112, 108, 97, 121, 61, 48, 38, 99, 105, 100, 61, 50, 56, 57, 48, 48, 56, 52, 52, 49, 38, 100, 105, 100, 61, 75, 82, 69, 104, 69, 83, 77, 85, 74, 104, 56, 116, 70, 67, 69, 86, 97, 82, 86, 112, 69, 50, 116, 97, 80, 81, 107, 55, 87, 67, 104, 67, 74, 103, 38, 101, 112, 105, 100, 61, 48, 38, 102, 116, 105, 109, 101, 61, 49, 54, 50, 55, 49, 48, 48, 57, 51, 55, 38, 108, 118, 61, 48, 38, 109, 105, 100, 61, 48, 38, 112, 97, 114, 116, 61, 49, 38, 115, 105, 100, 61, 48, 38, 115, 116, 105, 109, 101, 61, 49, 54, 50, 55, 49, 48, 52, 51, 55, 50, 38, 115, 117, 98, 95, 116, 121, 112, 101, 61, 48, 38, 116, 121, 112, 101, 61, 51};\n\n String dataString = new String(dataList);\n System.out.println("\u5b57\u7b26\u4e32\u662f\uff1a" + dataString);\n\n \/\/ 2.\u5b57\u7b26\u4e32->\u5b57\u8282\u6570\u7ec4\n try {\n \/\/ Python\u4e2d\u7684 name.encode("gbk")\n String name = "\u6b66\u6c9b\u9f50";\n byte[] v1 = name.getBytes("GBK");\n System.out.println(Arrays.toString(v1)); \/\/ [-50, -28, -59, -26, -58, -21]\n\n \/\/ Python\u4e2d\u7684 name.encode("utf-8")\n byte[] v2 = name.getBytes("UTF-8");\n System.out.println(Arrays.toString(v2)); \/\/ [-26, -83, -90, -26, -78, -101, -23, -67, -112]\n } catch (Exception e) {\n\n }\n }\n}\n<\/code><\/pre>\n![\"image-20220127173504514\"](\"https:\/\/lemon-guess.oss-cn-hangzhou.aliyuncs.com\/img\/image-20220127173504514.png\")
<\/p>\n
\u9700\u6c42\u6765\u4e86\uff1a\u67d0\u4e2aapp\u9006\u5411\uff0c\u5728Java\u4ee3\u7801\u4e2d\u5f97\u5230\u4e00\u4e2a\u5b57\u8282\u6570\u7ec4 [-50,-28,-59,-26,-58,-21]<\/code>\uff0c\u8bf7\u901a\u8fc7Python\u4ee3\u7801\u5c06\u8fd9\u4e2a\u5b57\u8282\u6570\u7ec4\u8f6c\u6362\u6210\u5b57\u7b26\u4e32\uff1f<\/p>\n\n\n- \n
\u5728Java\u4e2d\u7684\u5b57\u8282\u8303\u56f4\uff1a-128~127\uff1bPython\u4e2d\u5b57\u8282\u7684\u8303\u56f4\uff1a0~255\u3002<\/p>\n
Java 0 1 2 3 4 .. 127 -128 -127 -126 -3 -2 -1 \nPython 0 1 2 3 4 .. 127 128 129 130 ...253 254 255<\/code><\/pre>\njava, \u6709\u7b26\u53f7\uff1a-128~127\npython\uff0c\u65e0\u7b26\u53f7\uff1a0~255<\/code><\/pre>\nbyte_list = [-50,-28,-59,-26,-58,-21]<\/code><\/pre>\n<\/li>\n- \n
\u8ba9\u6570\u5b57\u8f6c\u5316\u5f04\u6210\u5b57\u8282\u5e76\u62fc\u63a5\u8d77\u6765 bytearray<\/p>\n<\/li>\n<\/ul>\n<\/blockquote>\n
# Python\u811a\u672c\uff0c\u65b9\u4fbf\u4f60\u4eec\u4ee5\u540e\u4f7f\u7528\u3002\nbyte_list = [-50, -28, -59, -26, -58, -21]\n\nbs = bytearray() # python\u5b57\u8282\u6570\u7ec4\nfor item in byte_list:\n if item < 0:\n item = item + 256\n bs.append(item)\n\nstr_data = bs.decode('gbk') # data = bytes(bs)\nprint(str_data)<\/code><\/pre>\n2.4.2 \u5b57\u7b26<\/h4>\nchar v1 = 'x';\nchar v2 = '\u6b66';\n\nString = "\u6b66\u6c9b\u9f50";<\/code><\/pre>\n\u6ce8\u610f\uff1a\u5b57\u7b26\u4e32\u662f\u7531\u591a\u4e2a\u5b57\u7b26\u4e32\u7ec4\u6210\u3002<\/p>\n
2.4.3 \u5b57\u7b26\u4e32<\/h4>\n
\u5b9a\u4e49\u5b57\u7b26\u4e32<\/p>\n
import java.io.UnsupportedEncodingException;\n\npublic class Hello {\n\n public static void main(String[] args) throws UnsupportedEncodingException {\n String v1 = "\u6b66\u6c9b\u9f50";\n String v2 = new String("\u6b66\u6c9b\u9f50");\n\n String v4 = new String(new byte[]{-26, -83, -90, -26, -78, -101, -23, -67, -112});\n String v5 = new String(new byte[]{-50, -28, -59, -26, -58, -21}, "GBK");\n\n String v6 = new String( new char[]{'\u6b66', '\u6c9b', '\u9f50'} ) ;\n }\n}<\/code><\/pre>\n\u5b57\u7b26\u4e32\u4e2d\u7684\u65b9\u6cd5\uff1a<\/p>\n
public class Hello {\n\n public static void main(String[] args) {\n String origin = "alex\u662f\u4e2a\u5927DB";\n\n char v1 = origin.charAt(5); \/\/ \u6307\u5b9a\u5b57\u7b26\n int len = origin.length(); \/\/ \u957f\u5ea6\n for (int i = 0; i < len; i++) {\n char item = origin.charAt(i);\n }\n\n String v2 = origin.trim(); \/\/ \u53bb\u9664\u7a7a\u767d\n String v3 = origin.toLowerCase(); \/\/ \u5c0f\u5199\n String v4 = origin.toUpperCase(); \/\/ \u5927\u5199\n String[] v5 = origin.split("\u662f"); \/\/ \u5206\u5272\n String v6 = origin.replace("D", "S"); \/\/ \u66ff\u6362\n\n String v7 = origin.substring(2, 6); \/\/ \u5b50\u5b57\u7b26\u4e32=\u5207\u7247 [2:6]\n\n boolean v8 = origin.equals("alex\u662f\u4e2a\u5927SB"); \/\/ "alex\u662f\u4e2a\u5927DB" "alex\u662f\u4e2a\u5927SB"\n\n boolean v9 = origin.contains("el");\n\n boolean v10 = origin.startsWith("a");\n\n String v11 = origin.concat("\u54c8\u54c8\u54c8");\n }\n}<\/code><\/pre>\nname = 'alex'\nif name == 'sb':\n pass<\/code><\/pre>\n\u5b57\u7b26\u4e32\u62fc\u63a5<\/p>\n
import java.io.UnsupportedEncodingException;\n\npublic class Hello {\n\n public static void main(String[] args) {\n \/\/ "name=alex&age=18"\n StringBuilder sb = new StringBuilder(); \/\/ StringBuffer\u7ebf\u7a0b\u5b89\u5168\n sb.append("name");\n sb.append("=");\n sb.append("alex");\n sb.append("&");\n sb.append("age");\n sb.append("=");\n sb.append("18");\n String dataString = sb.toString();\n\n System.out.println(dataString);\n }\n}<\/code><\/pre>\ndata = []\ndata.append("name")\ndata.append("=")\ndata.append("18")\ndata_string = "".join(data)<\/code><\/pre>\n![\"image-20220127174147151\"](\"https:\/\/lemon-guess.oss-cn-hangzhou.aliyuncs.com\/img\/image-20220127174147151.png\")
<\/p>\n
![\"image-20220127173632438\"](\"https:\/\/lemon-guess.oss-cn-hangzhou.aliyuncs.com\/img\/image-20220127173632438.png\")
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![\"image-20220127173906405\"](\"https:\/\/lemon-guess.oss-cn-hangzhou.aliyuncs.com\/img\/image-20220127173906405.png\")
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2.4.4 \u6570\u7ec4<\/h4>\n
\u5b58\u653e\u56fa\u5b9a\u957f\u5ea6\u7684\u5143\u7d20\u3002<\/p>\n
\n- \u5bb9\u5668<\/li>\n
- \u56fa\u5b9a\u957f\u5ea6<\/li>\n
- \u7279\u5b9a\u7c7b\u578b<\/li>\n<\/ul>\n
import java.util.Arrays;\n\npublic class Hello {\n\n public static void main(String[] args) {\n \/\/ [123,1,999]\n int[] numArray = new int[3];\n numArray[0] = 123;\n numArray[1] = 1;\n numArray[2] = 99;\n\n System.out.println(Arrays.toString(numArray));\n\n String[] names = new String[]{"\u6b66\u6c9b\u9f50", "alex", "eric"};\n System.out.println(Arrays.toString(names));\n\n String[] nameArray = {"\u6b66\u6c9b\u9f50", "alex", "eric"};\n System.out.println(Arrays.toString(nameArray));\n\n \/\/ nameArray[0]\n \/\/ nameArray.length\n for (int idx = 0; idx < nameArray.length; idx++) {\n String item = nameArray[idx];\n }\n\n }\n}<\/code><\/pre>\n\u6ce8\u610f\uff1a\u6570\u7ec4\u4e00\u65e6\u521b\u5efa\u4e2a\u6570\u5c31\u4e0d\u53ef\u8c03\u6574\u3002<\/p>\n
2.4.5 \u5173\u4e8eObject<\/h4>\n\n\n- \n
\u5728Python\u4e2d\u6bcf\u4e2a\u7c7b\u90fd\u9ed8\u8ba4\u7ee7\u627fObject\u7c7b\uff08\u6240\u6709\u7684\u7c7b\u90fd\u662fObject\u7684\u5b50\u7c7b\uff09\u3002<\/p>\n<\/li>\n
- \n
\u5728Java\u6240\u6709\u7684\u7c7b\u90fd\u662f\u9ed8\u8ba4\u7ee7\u627fObject\u7c7b\u3002<\/p>\n
int v1 = 123;\nString name = \"\u6b66\u6c9b\u9f50\";<\/code><\/pre>\n\u7528\u57fa\u7c7b\u53ef\u4ee5\u6cdb\u6307\u4ed6\u7684\u5b50\u7c7b\u7684\u7c7b\u578b\u3002<\/p>\n<\/li>\n<\/ul>\n<\/blockquote>\n
import sun.lwawt.macosx.CSystemTray;\n\nimport java.util.Arrays;\n\npublic class Hello {\n\n public static void main(String[] args) {\n \/\/ String v1 = "wupeiqi";\n Object v1 = new String("wupeiqi");\n System.out.println(v1);\n System.out.println(v1.getClass());\n\n Object v2 = 123;\n System.out.println(v2);\n System.out.println(v2.getClass());\n }\n}<\/code><\/pre>\nimport sun.lwawt.macosx.CSystemTray;\n\nimport java.util.Arrays;\n\npublic class Hello {\n\n public static void main(String[] args) {\n \/\/ \u58f0\u660e\u6570\u7ec4\uff0c\u6570\u7ec4\u4e2d\u5143\u7d20\u5fc5\u987bint\u7c7b\u578b;\n int[] v1 = new int[3];\n\n \/\/ \u58f0\u660e\u6570\u7ec4\uff0c\u6570\u7ec4\u4e2d\u5143\u7d20\u5fc5\u987bString\u7c7b\u578b;\n String[] v2 = new String[3];\n\n \/\/ \u58f0\u660e\u6570\u7ec4\uff0c\u6570\u7ec4\u4e2d\u53ef\u4ee5\u662f\u5fc5\u987bint\/String\u7c7b\u578b;\n Object[] v3 = new Object[3];\n v3[0] = 123;\n v3[1] = "wupeiqi";\n\n }\n}<\/code><\/pre>\n\u6240\u4ee5\uff0c\u5982\u679c\u4ee5\u540e\u60f3\u8981\u58f0\u660e\u7684\u6570\u7ec4\u4e2d\u60f3\u8981\u662f\u6df7\u5408\u7c7b\u578b\uff0c\u5c31\u53ef\u4ee5\u7528Object\u6765\u5b9e\u73b0\u3002<\/p>\n
import java.util.Arrays;\n\npublic class Hello {\n\n public static void main(String[] args) {\n \/\/ v1\u662f\u6307\u4e0a\u5b57\u7b26\u4e32\u5bf9\u8c61\uff1bString\n String v1 = new String("wupeiqi");\n String res = v1.toUpperCase();\n System.out.println(res);\n\n \/\/ v2\u672c\u8d28\u662f\u5b57\u7b26\u4e32\u5bf9\u8c61\uff1bObject\n Object v2 = new String("wupeiqi");\n String data = (String)v2;\n }\n}<\/code><\/pre>\nimport java.util.Arrays;\n\npublic class Hello {\n\n public static void func(Object v1) {\n \/\/ System.out.println(v1);\n \/\/ System.out.println(v1.getClass());\n if (v1 instanceof Integer) {\n System.out.println("\u6574\u578b");\n } else if (v1 instanceof String) {\n System.out.println("\u5b57\u7b26\u4e32\u7c7b\u578b");\n } else {\n System.out.println("\u672a\u77e5\u7c7b\u578b");\n }\n }\n\n public static void main(String[] args) {\n func(123);\n func("123");\n }\n}<\/code><\/pre>\n\n- Java\u4e2d\u6240\u6709\u7684\u7c7b\u90fd\u7ee7\u627fObject\uff0cObject\u4ee3\u6307\u6240\u6709\u7684\u7c7b\u578b\u3002<\/li>\n
- \u81ea\u5df1\u521b\u5efa\u5173\u7cfb
\n![\"image-20220127224643681\"](\"https:\/\/lemon-guess.oss-cn-hangzhou.aliyuncs.com\/img\/image-20220127224643681.png\")
<\/li>\n<\/ul>\nArrayList v1 = new ArrayList();\nLinkedList v2 = new LinkedList();<\/code><\/pre>\nList v1 = new ArrayList();\nList v2 = new LinkedList();<\/code><\/pre>\nObject v1 = new ArrayList();\nObject v2 = new LinkedList();<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"day02 \u8bc1\u4e66\u548cJava\u5165\u95e8 \u4eca\u65e5\u6982\u8981\uff1a https\u8bc1\u4e66\u95ee\u9898\uff0c\u5b89\u53537\u53ca\u4ee5\u4e0a\u3002 java\u57fa\u7840 \u4e0a\u4e00\u8282\u4e86\u89e3\u521d\u6b65\u4e86\u89e3\u4e86app\u9006\u5411\uff0c\u5e76\u4e14\u53d1\u73b0\u5982 \u2026 …<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"ngg_post_thumbnail":0},"categories":[209],"tags":[],"_links":{"self":[{"href":"\/index.php?rest_route=\/wp\/v2\/posts\/8986"}],"collection":[{"href":"\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=8986"}],"version-history":[{"count":1,"href":"\/index.php?rest_route=\/wp\/v2\/posts\/8986\/revisions"}],"predecessor-version":[{"id":8987,"href":"\/index.php?rest_route=\/wp\/v2\/posts\/8986\/revisions\/8987"}],"wp:attachment":[{"href":"\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=8986"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=8986"},{"taxonomy":"post_tag","embeddable":true,"href":"\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=8986"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
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<\/p>\n![\"image-20220428191016704\"](\"https:\/\/lemon-guess.oss-cn-hangzhou.aliyuncs.com\/img\/image-20220428191016704.png\")
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<\/p>\n![\"image-20220428191439073\"](\"https:\/\/lemon-guess.oss-cn-hangzhou.aliyuncs.com\/img\/image-20220428191439073.png\")
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<\/p>\n![\"image-20220428193426241\"](\"https:\/\/lemon-guess.oss-cn-hangzhou.aliyuncs.com\/img\/image-20220428193426241.png\")
<\/p>\n<\/li>\n![\"image-20220428193533311\"](\"https:\/\/lemon-guess.oss-cn-hangzhou.aliyuncs.com\/img\/image-20220428193533311.png\")
<\/p>\n<\/li>\n<\/ul>\n![\"image-20220428204854249\"](\"https:\/\/lemon-guess.oss-cn-hangzhou.aliyuncs.com\/img\/image-20220428204854249.png\")
<\/p>\n![\"image-20210929141555448\"](\"https:\/\/lemon-guess.oss-cn-hangzhou.aliyuncs.com\/img\/image-20210929141555448.png\")
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