时代Java

Java 乘法表显示

欢马劈雪

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乘法表显示

实例源码：

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import java.util.*;/**N  o w  J a v a . c o m**/

public class MultiplicationTable {

public static void main(String[] args) throws Exception {

int begin = 1, end = 9;

if (args.length == 2) {

begin = Integer.parseInt(args[0]);

end = Integer.parseInt(args[1]);

}

SortedMap<Integer, List<Integer>> mt = multTable(begin, end);

printMultiplicationTable(mt);

System.out.println();

}

public static SortedMap<Integer, List<Integer>> multTable(int begin,/* 来 自 n o w j a v a . c o m*/

int end) {

if (begin < 0 || end < 0 || begin > end)

return null;

SortedMap<Integer, List<Integer>> mt = new TreeMap<>();

for (int i = begin; i <= end; ++i) {

List<Integer> li = new ArrayList<>();

for (int k = begin; k <= end; ++k)

li.add(i * k);

mt.put(i, li);

}

return mt;

}

public static void printMultiplicationTable(

SortedMap<Integer, List<Integer>> mt) {

Set<Integer> keys = mt.keySet();

Integer[] iKeys = keys.toArray(new Integer[0]);

Integer last = iKeys[iKeys.length - 1];

int width = Integer.toString(last * last).length() + 1;

String fmt = "%" + width + "d";

System.out.printf("%" + width + "s", "");

for (Integer k : keys)

System.out.printf(fmt, k);

System.out.println();

for (Integer k : keys) {

System.out.printf(fmt, k);

List<Integer> li = mt.get(k);

for (Integer i : li)

System.out.printf(fmt, i);

System.out.println();

}

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*     from this software without specific prior written permission.

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编辑于 2020-03-26 09:23:272020-03-26 09:23:27

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