Java 乘法表显示
乘法表显示
实例源码：
源代码：
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import java.util.*;/**N o w J a v a . c o m**/3
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public class MultiplicationTable {6
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public static void main(String[] args) throws Exception {9
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int begin = 1, end = 9;12
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if (args.length == 2) {15
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begin = Integer.parseInt(args[0]);17
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end = Integer.parseInt(args[1]);19
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}21
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SortedMap<Integer, List<Integer>> mt = multTable(begin, end);24
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printMultiplicationTable(mt);26
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System.out.println();28
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}30
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public static SortedMap<Integer, List<Integer>> multTable(int begin,/* 来 自 n o w j a v a . c o m*/33
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int end) {35
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if (begin < 0 || end < 0 || begin > end)38
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return null;40
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SortedMap<Integer, List<Integer>> mt = new TreeMap<>();43
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for (int i = begin; i <= end; ++i) {46
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List<Integer> li = new ArrayList<>();48
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for (int k = begin; k <= end; ++k)50
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li.add(i * k);52
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mt.put(i, li);55
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}57
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return mt;60
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}62
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public static void printMultiplicationTable(65
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SortedMap<Integer, List<Integer>> mt) {67
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Set<Integer> keys = mt.keySet();70
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Integer[] iKeys = keys.toArray(new Integer[0]);72
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Integer last = iKeys[iKeys.length - 1];74
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int width = Integer.toString(last * last).length() + 1;76
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String fmt = "%" + width + "d";78
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System.out.printf("%" + width + "s", "");81
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for (Integer k : keys)83
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System.out.printf(fmt, k);85
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System.out.println();87
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for (Integer k : keys) {90
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System.out.printf(fmt, k);92
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List<Integer> li = mt.get(k);95
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for (Integer i : li)97
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System.out.printf(fmt, i);99
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System.out.println();101
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}103
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}105
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}107
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/*110
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* Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved.112
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*114
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* Redistribution and use in source and binary forms, with or without116
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* modification, are permitted provided that the following conditions118
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* are met:120
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*122
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* - Redistributions of source code must retain the above copyright124
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* notice, this list of conditions and the following disclaimer.126
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*128
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* - Redistributions in binary form must reproduce the above copyright130
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* notice, this list of conditions and the following disclaimer in the132
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* documentation and/or other materials provided with the distribution.134
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*136
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* - Neither the name of Oracle or the names of its138
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* contributors may be used to endorse or promote products derived140
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* from this software without specific prior written permission.142
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*144
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS146
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* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,148
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* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR150
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