byte short int long float double char boolean
if (false){} else if (false){} else{}
for (int i = 1; i <= 10; i++) {}
int i=1;
while(i <= 10){}
int[] arr = {1,2,3,4,5};
int[] arr = new int[5];
for(int i = 0; i < arr.length; i++) {}
public static void
private protected interface package import
public static final
public abstract
java.lang.Math
Math.abs( )
Math.round( )
java.util.Random
java.lang.String
length( )
equals( )
charAt( )
indexOf( )
contains( )
trim( )
replace( )
substring(1, 3)
toUpperCase( )
split(";")
java.lang.StringBuffer
java.lang.StringBuilder
synchronized
java.util.Date
java.text.SimpleDateFormat
String t = "2021/12/20";
SimpleDateFormat sd = new SimpleDateFormat("yyyy/MM/dd");
Date e = sd.parse(t);
Date d = new Date();
SimpleDateFormat s = new SimpleDateFormat("yyyy-MM-dd ");
String str = s.format(d);
java.lang.Integer
java.lang.Character
int a = 2;
String b = String.valueOf(a);
String c = "3";
int d = Integer.parseInt(c);
java.io.InputStream
java.io.OutputStream
java.io.Reader
java.io.Writer
FileReader f = new FileReader("d:/person.txt");
BufferedReader b = new BufferedReader(f);
FileWriter f = new FileWriter("d:/person2.txt", true);
BufferedWriter b = new BufferedWriter(f);
Throwable
Error
Exception
RuntimeException
Component
Repository
Service
Controller
Autowired
Resource
Controller
RequestMapping
ResponseBody
RestController
RequestParam
param
insert update delete select collection association resultMap result id
namespace id parameterType resultType resultMap id type property
column javaType ofType