JAVA-各種類型之間轉換 parse() 與valueOf()

類型互轉

1.各種類型轉String

2.String轉Bytes

3.數組轉List

4.進制轉換

5.

parse 在 SimpleDateFormat 中是轉換為Date類,其它的一些包裝類都是轉換為int/double等基本類

valueOf 轉換的是類 eg: Integer /Double/Float....

import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Scanner;

public class Main {
	
	public static void main(String[] args) throws Exception {
		Integer a = 12;
		
		Integer [] aaa = new Integer[10];
		for(int i = 0;i<10;i++)
			aaa[i] = new Integer(i);//對象數組要一個一個new
		System.out.println(Arrays.toString(aaa));//自己主動拆包 數組轉String
		System.out.println(Integer.toBinaryString(a));//String
		System.out.println(Integer.toHexString(a));//String
		String t = "23";
		byte [] b = t.getBytes();
		Integer aa = Integer.parseInt(t, 10);
		System.out.println(aa);
		List list = Arrays.asList(aaa);	
		System.out.println(list);
		aaa = (Integer [])list.toArray(new Integer[0]);
		System.out.println(Arrays.toString(aaa));
	}
}
/*
 * [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
 *1100
 *c
 *23
 *[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
 *[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
 */
class Child extends Main {
	
}