{"id":529,"date":"2013-01-29T23:44:00","date_gmt":"2013-01-29T15:44:00","guid":{"rendered":"http:\/\/note.systw.net\/note\/?p=529"},"modified":"2023-11-03T23:47:56","modified_gmt":"2023-11-03T15:47:56","slug":"java%e6%91%98%e8%a6%81","status":"publish","type":"post","link":"https:\/\/systw.net\/note\/archives\/529","title":{"rendered":"Java\u6458\u8981"},"content":{"rendered":"\n

java\u7a0b\u5f0f\u7bc4\u4f8b<\/strong>
ex:
\u6a94\u6848sample_code.java\u7a0b\u5f0f\u78bc\u5982\u4e0b<\/p>\n\n\n\n

public class sample_code\n{\n\u3000public static void main(String[] args)\n\u3000{\n\u3000System.out.println(\"hello wrold\");\n\u3000 }\n}<\/code><\/pre>\n\n\n\n
ps:\u539f\u59cb\u7a0b\u5f0f\u6a94\u5167\u7684\u985e\u5225\u540d\u7a31\u9700\u548c\u6a94\u540d\u76f8\u540c<\/p>\n\n\n\n

java\u8cc7\u6599\u578b\u5225\u5ba3\u544a<\/strong>
boolean :1bit,true or false
byte :8bit,\u4f4d\u5143\u7d44,-128~127
char :16bit,Unicode characters
short :16bit,\u77ed\u6574\u6578,-32768 ~ 32767
int :32bit,\u6574\u6578,-2147483648 ~ 2147483647
long :64bit,\u9577\u6574\u6578,-9223372036854775808 ~ 9223372036854775807
float :32bit ,\u6d6e\u9ede\u6578
double :64bit,\u6d6e\u9ede\u6578
\u5ba3\u544a\u65b9\u5f0f<\/strong>
< datatype> < variable1 [, variable2,…]>
ex:
int var1;
int var1,int1;<\/p>\n\n\n\n
………………<\/p>\n\n\n\n
java\u8b8a\u6578<\/strong>
1. \u540d\u7a31\u53ef\u4efb\u610f\u9577,\u6709\u5927\u5c0f\u5beb\u4e4b\u5206
2. \u540d\u7a31\u7b2c\u4e00\u500b\u5b57\u9808\u70baletter(\u5b57\u6bcd)\u6216underscore(\u5e95\u7dda)\u6216dollar sign(\u9322\u865f)
3. \u540d\u7a31\u4e0d\u53ef\u70ba\u95dc\u9375\u5b57
4. \u8b8a\u6578\u5132\u503c\u683c\u5f0f:[datatype] < variable> = < value>
ex:
var1=100;
var2=’a’;
char var3=’b’;
5. \u8b8a\u6578\u578b\u614b\u8f49\u63db\u683c\u5f0f: < (datatype)>< variable1>
ex:
(double)var1<\/p>\n\n\n\n

\u5e38\u898b\u95dc\u9375\u5b57\u5982\u4e0b<\/strong>
\u8a2a\u554f\u63a7\u5236:<\/strong>
private \u79c1\u6709\u7684
protected \u53d7\u4fdd\u8b77\u7684
public \u516c\u5171\u7684
\u985e\u3001\u65b9\u6cd5\u548c\u8b8a\u91cf\u4fee\u98fe\u7b26<\/strong>
abstract \u8072\u660e\u62bd\u8c61
class \u985e
extends \u64f4\u5141,\u7e7c\u627f
final \u7d42\u6975,\u4e0d\u53ef\u6539\u8b8a\u7684
implements\u5be6\u73fe
interface \u63a5\u53e3
native \u672c\u5730
new \u65b0,\u5275\u5efa
static \u975c\u614b
strictfp \u56b4\u683c,\u7cbe\u6e96
synchronized \u7dda\u7a0b,\u540c\u6b65
transient \u77ed\u66ab
volatile \u6613\u5931
\u7a0b\u5e8f\u63a7\u5236\u8a9e\u53e5<\/strong>
break \u8df3\u51fa\u5faa\u74b0
continue \u7e7c\u7e8c
return \u8fd4\u56de
do \u904b\u884c
while \u5faa\u74b0
if \u5982\u679c
else \u53cd\u4e4b
for \u5faa\u74b0
instanceof \u5be6\u4f8b
switch \u958b\u95dc
case \u8fd4\u56de\u958b\u95dc\u91cc\u7684\u7d50\u679c
default \u9ed8\u8a8d
\u932f\u8aa4\u8655\u7406<\/strong>
catch \u8655\u7406\u7570\u5e38
finally \u6709\u6c92\u6709\u7570\u5e38\u90fd\u57f7\u884c
throw \u62cb\u51fa\u4e00\u500b\u7570\u5e38\u5c0d\u8c61
throws \u8072\u660e\u4e00\u500b\u7570\u5e38\u53ef\u80fd\u88ab\u62cb\u51fa
try \u6355\u7372\u7570\u5e38
\u5305\u76f8\u95dc<\/strong>
import \u5f15\u5165
package \u5305
\u57fa\u672c\u985e\u578b<\/strong>
boolean \u5e03\u723e\u578b
byte \u5b57\u7bc0\u578b
char \u5b57\u7b26\u578b
double \u96d9\u7cbe\u5ea6,
float \u6d6e\u9ede
int \u6574\u578b
long \u9577\u6574\u578b
short \u77ed\u6574\u578b
null \u7a7a
true \u771f
false \u5047
\u8b8a\u91cf\u5f15\u7528<\/strong>
super \u7236\u985e,\u8d85\u985e
this \u672c\u985e
void \u7121\u8fd4\u56de\u503c<\/p>\n\n\n\n
………………………….<\/p>\n\n\n\n
\u5e38\u7528\u6578\u5b78\u51fd\u5f0f<\/strong>
\u5c0d\u6578\u548c\u6307\u6578<\/strong>
Math.exp(double): \u81ea\u7136\u6307\u6578
Math.log(double): \u81ea\u7136\u5c0d\u6578
Math.sqrt(double): \u958b\u6839\u865f
Math.pow(double, int):\u5e73\u65b9
\u4e82\u6578\u548c\u5c0f\u6578<\/strong>
Math.random(): \u50b3\u56de0.0 ~ 1.0\u4e4b\u9593\u7684\u4e82\u6578
Math.round(double): \u56db\u6368\u4e94\u5165\u5f8c\u50b3\u56de\u6574\u6578
Math.ceil(double): \u7121\u689d\u4ef6\u9032\u4f4d
Math.floor(double): \u7121\u689d\u4ef6\u6368\u53bb
Math.abs(n): \u50b3\u56de\u7d55\u5c0d\u503c
\u6700\u5927\u8207\u6700\u5c0f<\/strong>
Math.max()
Math.min()<\/p>\n\n\n\n
………………………………..<\/p>\n\n\n\n
\u9663\u5217<\/strong><\/p>\n\n\n\n
\u5ba3\u544a
\u65b9\u6cd51
< datetype> < arrayname>[ ] =new < datatype>[< num>];<\/strong>
ex:
int ary1[] = new int[5]; \/\/\u5ba3\u544a\u4e00\u500bint\u985e\u578b\u9663\u5217,\u4e26\u914d\u7f6e5\u500bint\u5143\u7d20\u7a7a\u9593
int ary2[][] = new int[5][6]; \/\/\u5ba3\u544a\u4e00\u500bint\u985e\u578b2\u7dad\u9663\u5217,\u4e26\u914d\u7f6e5*6\u500bint\u5143\u7d20\u7a7a\u9593
\u65b9\u6cd52
< datetype> < arrayname>[ ] ;
< arrayname>=new < datatype>[< num>];<\/strong>
ex:
int ary1[]; \/\/\u5ba3\u544a\u4e00\u500bint\u985e\u578b\u9663\u5217,
ary1=new int[5]; \/\/\u914d\u7f6e5\u500bint\u5143\u7d20\u7a7a\u9593
int ary2[][]; \/\/\u5ba3\u544a\u4e00\u500bint\u985e\u578b2\u7dad\u9663\u5217,
ary2=new int[5][6]; \/\/\u914d\u7f6e5*6\u500bint\u5143\u7d20\u7a7a\u9593<\/p>\n\n\n\n

\u4f7f\u7528<\/strong>
< arrayname>[< index>]=< value><\/strong>
ex:
ary[3] = 10; \/\/ \u8a2d\u5b9a\u7b2c4\u500b\u5143\u7d20\u70ba10<\/p>\n\n\n\n
\u5ba3\u544a+\u4f7f\u7528<\/strong>
< datatype> < arrayname>[] = {value1, value2, …};<\/strong>
ex:
int ary[5] = {1, 2, 3, 5,8}; \/\/\u5ba3\u544a\u9663\u5217\u4e26\u5c07\u503c\u52a0\u5165<\/p>\n\n\n\n
\u5217\u51fa\u9663\u5217<\/strong>
System.out.println(ary); \/\/\u5217\u51fa\u9663\u5217\u6240\u6709\u5143\u7d20
System.out.println(ary[1]); \/\/\u5217\u51fa\u9663\u5217\u7b2c2\u500b\u5143\u7d20<\/p>\n\n\n\n
\u53d6\u5f97\u9663\u5217\u9577\u5ea6<\/strong>
arrayname.length
ex:
\u8a2d\u9663\u5217\u70baint ary[][][] = new int[3][4][5];
ary.length \/\/\u8868\u793a3
ary[0].length \/\/\u8868\u793a4
ary[0][0] .length \/\/\u8868\u793a5<\/p>\n\n\n\n
………………………………………………….<\/p>\n\n\n\n
\u5176\u4ed6\u7528\u6cd5<\/strong><\/p>\n\n\n\n
\u5c07\u4e3b\u7a0b\u5f0f\u8207\u8655\u7406\u4f8b\u5916\u72c0\u6cc1\u7684\u7a0b\u5f0f\u5206\u958b
try {
\/\/ code body
\/\/ \u57f7\u884c\u6642\u82e5\u7522\u751fIO Exception,\u5247\u9032\u5165catch
} catch (IOException e) {
\/\/ \u8655\u7406IO Exception\u7684code
\/\/ ex: System.out.println(e);
} <\/p>\n","protected":false},"excerpt":{"rendered":"
java\u7a0b\u5f0f\u7bc4\u4f8bex:\u6a94\u6848sample_code.java\u7a0b …<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"fifu_image_url":"","fifu_image_alt":"","_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[14],"tags":[],"class_list":["post-529","post","type-post","status-publish","format-standard","hentry","category-develop"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/posts\/529","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/comments?post=529"}],"version-history":[{"count":0,"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/posts\/529\/revisions"}],"wp:attachment":[{"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/media?parent=529"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/categories?post=529"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/tags?post=529"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}