Conversion between String, Integer, and int in Java data types

1. The method of converting Integer to int

Integer i = new Integer(10); 
int k = i.intValue();
即Integer.intValue();

 

2. Convert int to Integer

int i = 10;

Integer it = new Integer(i);

 

3. Method of converting String to int

String str = "10";  
Integer it = new Interger(str);  

int i = it.intValue();  

即：int i = Integer.intValue(string);

 

4. Convert int to String

int i = 10;

(1)String s = String.valueOf(i);

(2)String s = Ingeger.toString(i);

(3)String s = "" + i;

 

5. Convert String to Integer

String str = "10";

Integer it = Integer.valueOf(str);

 

6. Convert Integer to String

Integer it = new Integer(10);

String str = it.toString();

 

7. Convert String to BigDecimal

BigDecimal bd = new BigDecimal(str);

 

8. Date

Calendar calendar = Calendar.getInstance();
int year = calendar.get(Calendar.YEAR);
int month = calendar.get(Calendar.MONTH)+1;
int day = calendar.get(Calendar.DATE);

//获取今天的日期字符串
String today = java.text.DateFormat.getDateInstance().format(new java.util.Date());
//获取今天的日期
new java.sql.Date(System.currentTimeMillis());