【学习记录】Java常用类型转换

• 1.字符串与字符数组互转
• 2.字符串与字符串数组转换
• 3.字符数组与列表转换
• 4.整型数组与列表转换
• 5.字符串与整形转换

public static void main(String[] args) {
	String s = "Hello World!";
	char [] c = s.toCharArray();
	System.out.println(c);
}

此时c[0]与s.CharAt(0)都表示 ‘H’

public static void main(String[] args) {
	char [] c = {'H','e','l','l','o',' ','W','o','r','l','d','!'};
	String s = new String(c);
	String s1 = String.valueOf(c);
	System.out.println(s);
	System.out.println(s1);
}

public static void main(String[] args) {
	String s = "Hello World!";
	String [] array = s.split("");
	for(String c : array)
	System.out.print(c);
}

public static void main(String[] args) {
	String [] array = {"H","e","l","l","o"," ","W","o","r","l","d","!"};
	StringBuilder sb = new StringBuilder();
	for(String s : array)
		sb.append(s);
	System.out.println(sb.toString());
}

public static void main(String[] args) {
	String [] array = {"H","e","l","l","o"," ","W","o","r","l","d","!"};
	List list = Arrays.asList(array); 
	for(String s : list)
		System.out.print(s);
}

public static void main(String[] args) {
	List list = new ArrayList();
	list.add("H");
	list.add("W");
	String [] array = new String[list.size()];
	list.toArray(array);
	for(String s : array)
		System.out.println(s);
	}

public static void main(String[] args) {
		int [] array = {1,2,4,5,6,7};
		List list = Arrays.stream(array).boxed().collect(Collectors.toList());
		for(int i : array)
			System.out.print(i);
}

public static void main(String[] args) {
		List list = new ArrayList();
		list.add(Integer.parseInt("1"));
		list.add(Integer.parseInt("2"));
		Integer [] array = new Integer [list.size()];
		list.toArray(array);
		for(int s : array)
			System.out.print(s);
	}

public static void main(String[] args) {
		String s = "666";
		int a = Integer.parseInt(s);
		System.out.println(a);
}

public static void main(String[] args) {
		int a = 666;
		String s = Integer.toString(a);
		System.out.println(s);
	}