8 kinds of conversion between data types (rpm)

Converting data types between 8

May 6, 2019 11:41:15  help should -  read: 11

 

 Copyright: copyright belongs to himself all https://blog.csdn.net/weixin_42295141/article/details/89879196

package com.itheima;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

public class various conversion {
public static void main(String[] args) throws ParseException {
/*
1. The basic data type conversion *
*/
// implicit conversion byte, short, char - int - long - float - double
// cast
int a = 12;
byte b = (byte) a;

/*
* 2.String StringBuilder
*/
//String to StringBuilder
StringBuilder sb = new StringBuilder("abcde");
//StringBuilder to String
String s = sb.toString();

/*
* 3.String and arrays
*/
// String to an array
String ss = "abcdefg";
char [] charArray = ss.toCharArray ();
byte[] bytes = ss.getBytes();
// Array to String
String bys = new String(bytes);
String chs = new String(charArray);

* 4 String and basic data types
// basic data types to String
int an = 10;
String aa = an+ "";
String aa1 = String.valueOf(an);

// String to basic data types
int bb = Integer.parseInt("123");
//String to int
char charAt = "123".charAt(0);
//String to char

/*
* 5 String transfer case
*/
String bigSmall = "AbCdEf";
String big = bigSmall.toUpperCase();
String small = bigSmall.toLowerCase();

/*
6 * Automatic boxing and unboxing
*/
I = Integer 123; // autoboxing
II = I int; // automatically unpacking

/*
* 7 Date and String

Date d = new Date();
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String format = sdf.format(d);
//Date to String
Date parse = sdf.parse(format);
//String to Date

* 8 Date and Calendar

Date date = new Date();
Calendar cal = Calendar.getInstance();
Date time = cal.getTime();
//Calendar to Date
cal.setTime(date);
//Date to Calendar