字符串写入文件java java字符串存入字符数组

1. 数组转List

String[] staffs = new String[]{"Tom", "Bob", "Jane"};
List staffsList = Arrays.asList(staffs);

需要注意的是， Arrays.asList() 返回一个受指定数组决定的固定大小的列表。所以不能做 add 、 remove 等操作，否则会报错。

List staffsList = Arrays.asList(staffs);
staffsList.add("Mary"); // UnsupportedOperationException
staffsList.remove(0); // UnsupportedOperationException

 如果想再做增删操作呢？将数组中的元素一个一个添加到列表，这样列表的长度就不固定了，可以进行增删操作。

List staffsList = new ArrayList<String>();
for(String temp: staffs){
  staffsList.add(temp);
}
staffsList.add("Mary"); // ok
staffsList.remove(0); // ok

2.数组转Set

String[] staffs = new String[]{"Tom", "Bob", "Jane"};
Set<String> staffsSet = new HashSet<>(Arrays.asList(staffs));
staffsSet.add("Mary"); // ok
staffsSet.remove("Tom"); // ok

3.List转数组

String[] staffs = new String[]{"Tom", "Bob", "Jane"};
List staffsList = Arrays.asList(staffs);

Object[] result = staffsList.toArray();

4.List转Set

String[] staffs = new String[]{"Tom", "Bob", "Jane"};
List staffsList = Arrays.asList(staffs);

Set result = new HashSet(staffsList);

 5.Set转数组

String[] staffs = new String[]{"Tom", "Bob", "Jane"};
Set<String> staffsSet = new HashSet<>(Arrays.asList(staffs));

Object[] result = staffsSet.toArray();

 6.Set转List

String[] staffs = new String[]{"Tom", "Bob", "Jane"};
Set<String> staffsSet = new HashSet<>(Arrays.asList(staffs));

List<String> result = new ArrayList<>(staffsSet);

 7.数组和字符串转换

public static void main(String[] args) {
		//1.字符数组 转换成 字符串
		//(1)直接在构造String时转换
		char[] array = new char[] {'a','b','c','d','e','f','g'};
		String str = new String(array);
		System.out.println(str);
		
		//(2)调用String类的提供的方法的valueOf()
		String str2 = String.valueOf(array);
		System.out.println(str2);
		
		//2.字符串  转换成 字符数组 
		//(1)调用String类的提供的方法的toCharArray()
		String msg = "i am a good boy!";
		char[] dest = msg.toCharArray();
		System.out.println(Arrays.toString(dest));
	}