public class Insert {
/**
* @param args
*/
public static void main(String[] args) {
System.out.println(insert("ab打def", "abc", 3));
System.out.println(inversion("ab打def"));
}
/**
* 插入字符串
*/
public static String insert(String info, String insert, int index) {
if (info == null || insert == null) {
throw new NullPointerException(
"the insert string is null or the info string is null.");
}
if (info.length() < index) {
throw new IndexOutOfBoundsException(
"the insert index is out of bounds.");
}
char[] buffer = null;
if (info.length() == 0) {
return insert;
} else if (insert.length() == 0) {
return info;
} else {
buffer = new char[info.length() + insert.length()];
for (int i = 0; i < info.length(); i++) {
if (i < index) {
buffer[i] = info.charAt(i);
} else {
buffer[i + insert.length()] = info.charAt(i);
}
}
for (int i = 0; i < insert.length(); i++) {
buffer[index + i] = insert.charAt(i);
}
}
return new String(buffer);
}
/**
* 反转
*/
public static String inversion(String info) {
if (info == null) {
throw new NullPointerException("the info string is null.");
}
char[] buffer = new char[info.length()];
for (int i = 0; i < info.length(); i++) {
buffer[i] = info.charAt(info.length() - i - 1);
}
return new String(buffer);
}
}
