如何向字符数组添加字符

char[] arr = {'H', 'e', 'l', 'l', 'o'};
char c = '!';
String result = new String(arr) + c;

char[] arr = {'H', 'e', 'l', 'l', 'o'};
char c = '!';
StringBuilder sb = new StringBuilder();
sb.append(arr);
sb.append(c);
String result = sb.toString();

char[] arr = {'H', 'e', 'l', 'l', 'o'};
char c = '!';
char[] newArr = new char[arr.length + 1];
System.arraycopy(arr, 0, newArr, 0, arr.length);
newArr[arr.length] = c;
String result = new String(newArr);