版本1(探索版)
package experiment6.exp3;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
/*依次输入10个不同的整数，一行输入一个整数。
若输入的整数与已经输入的整数相同，则抛出SameIntegerException异常，提示继续输入。
如：输入十个不同整数[10, 23, 39, 22, 48, 77, -2, 30, 8, 99]
*/
public class exp3 {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.println("请输入10个不同的整数,一个数一行:");
List<Integer> list = new ArrayList<>();
for (int i = 0; list.size()<10; i++) {
String line = scanner.nextLine();
//line = scanner.nextLine();
int tmp = Integer.parseInt(line);
if (list.contains(tmp)) {
try {
//list.add(tmp);
throw new SameIntegerException(tmp,list);
} catch (SameIntegerException e) {
e.printStackTrace();
System.out.println("请重新输入:");
}
}else
{
list.add(tmp);
}
}//endFor
System.out.println("输入的10个不同整数为:\n"+list);
}//endMain
}
/*测试数据:
10
23
39
10
22
48
39
77
-2
48
30
8
-2
99
*/
package experiment6.exp3;
import java.util.ArrayList;
import java.util.List;
public class SameIntegerException extends Exception{
int m;
List<Integer> list=new ArrayList<>();
public SameIntegerException(int n,List<Integer> argList){
m=n;
list=argList;
}
public String getMessage() {
return "输入的数"+m+"和已输入的数"+list+"有相同\n";
}
}
改进版
package experiment6.exp3;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
/*依次输入10个不同的整数，一行输入一个整数。
若输入的整数与已经输入的整数相同，则抛出SameIntegerException异常，提示继续输入。
如：输入十个不同整数[10, 23, 39, 22, 48, 77, -2, 30, 8, 99]
*/
public class exp3 {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.println("请输入10个不同的整数,一个数一行:");
List<Integer> list = new ArrayList<>();
AddDifferentNum obj=new AddDifferentNum();
for (int i = 0; list.size() < 10; i++) {
String line = scanner.nextLine();
int tmp = Integer.parseInt(line);
try{
obj.add(list, tmp);
}catch (SameIntegerException e){
e.printStackTrace();//区别于getStackTrace();方法.
System.out.println("请重新输入:");
}
}//endFor
System.out.println("输入的10个不同整数为:\n"+list);
}//endMain
}
package experiment6.exp3;
import java.util.List;
public class SameIntegerException extends RuntimeException{
int m;
List<Integer> list;
public SameIntegerException(int n,List<Integer> argList){
m=n;
list=argList;
}
public String getMessage() {
return "输入的数"+m+"和已输入的数"+list+"有相同";//+"\n"
}
}
package experiment6.exp3;
import java.util.List;
public class AddDifferentNum {
public void add(List<Integer> list,int tmp)
{
if (list.contains(tmp)) {
throw new SameIntegerException(tmp, list);
} else {
list.add(tmp);
}
}
}
/*
附上样例:(从Integer.parseInt()的源代码可以看出,throw抛出异常后,不是在本方法中立即catch.
而且,throw xxException 在方法没有用try套住(尽管一般都是RunningTimeException)
不过这样将try...catch在调用者中执行,在程序捕捉到第一个异常后就离开了(方法中还未执行的部分就来不及执行完整)
也就是说,看需求啦,到底要不要在方法中直接处理(套上try...catch).
当然,一般如果业务逻辑分的分配的清楚合理的话,是可以值抛出if(){throw}后,让main()方法去try catch.
public static int parseInt(String s, int radix)
throws NumberFormatException
{
*
* WARNING: This method may be invoked early during VM initialization
* before IntegerCache is initialized. Care must be taken to not use
* the valueOf method.
*
if (s == null) {
throw new NumberFormatException("null");
}
if (radix < Character.MIN_RADIX) {
throw new NumberFormatException("radix " + radix +
" less than Character.MIN_RADIX");
}
if (radix > Character.MAX_RADIX) {
throw new NumberFormatException("radix " + radix +
" greater than Character.MAX_RADIX");
}
boolean negative = false;
int i = 0, len = s.length();
int limit = -Integer.MAX_VALUE;
if (len > 0) {
char firstChar = s.charAt(0);
if (firstChar < '0') { // Possible leading "+" or "-"
if (firstChar == '-') {
negative = true;
limit = Integer.MIN_VALUE;
} else if (firstChar != '+') {
throw NumberFormatException.forInputString(s, radix);
}
if (len == 1) { // Cannot have lone "+" or "-"
throw NumberFormatException.forInputString(s, radix);
}
i++;
}
int multmin = limit / radix;
int result = 0;
while (i < len) {
// Accumulating negatively avoids surprises near MAX_VALUE
int digit = Character.digit(s.charAt(i++), radix);
if (digit < 0 || result < multmin) {
throw NumberFormatException.forInputString(s, radix);
}
result *= radix;
if (result < limit + digit) {
throw NumberFormatException.forInputString(s, radix);
}
result -= digit;
}
return negative ? result : -result;
} else {
throw NumberFormatException.forInputString(s, radix);
}
}
*/
