java 遍历Map及Map转化为二维数组的实例

实例代码：

import java.util.HashMap; import java.util.Iterator; import java.util.Map; public class Test { public static void main(String[] args) { int a = 0, b = 0, c = 0; // 第一种:通过Map.keySet()遍历Map及将Map转化为二维数组 Map<String, String> map1 = new HashMap<String, String>(); map1.put("012013012013", "张三"); map1.put("012013012014", "张四"); String[][] group1 = new String[map1.size()][2]; System.out.println("第一种:通过Map.keySet()遍历map1的key和value"); for (String key : map1.keySet()) { System.out.println("key = " + key + " and value = " + map1.get(key)); group1[a][0] = key; group1[a][1] = map1.get(key); a++; } System.out.println("map1.size()为：" + map1.size() + ",a为：" + a + "，group1数组的长度为：" + group1.length); System.out.println("----------------------------------------------------"); for(int n = 0; n < group1.length; n++) { System.out.println("key = " + group1[n][0] + " and value = " + group1[n][1]); } // 第二种:通过Map.entrySet()使用iterator()遍历Map及将Map转化为二维数组 Map<String, String> map2 = new HashMap<String, String>(); map2.put("112013012013", "李三"); map2.put("112013012014", "李四"); System.out.println("\n" + "第二种:通过Map.entrySet()使用iterator()遍历map2的key和value"); Iterator<Map.Entry<String, String>> iterator = map2.entrySet().iterator(); String[][] group2 = new String[map2.size()][2]; while (iterator.hasNext()) { Map.Entry<String, String> entry = iterator.next(); System.out.println("key = " + entry.getKey() + " and value = " + entry.getValue()); group2[b][0] = entry.getKey(); group2[b][1] = entry.getValue(); b++; } System.out.println("map2.size()为：" + map2.size() + ",b为：" + b + "，group2数组的长度为：" + group2.length); System.out.println("----------------------------------------------------"); for(int n = 0; n < group2.length; n++) { System.out.println("key = " + group2[n][0] + " and value = " + group2[n][1]); } // 第三种:通过Map.entrySet()遍历遍历Map及将Map转化为二维数组 Map<String, String> map = new HashMap<String, String>(); map.putAll(map1); map.putAll(map2); String[][] group3 = new String[map.size()][2]; System.out.println("\n" + "第三种:通过Map.entrySet()遍历map的key和value "); for (Map.Entry<String, String> entry : map.entrySet()) { System.out.println("key = " + entry.getKey() + " and value = " + entry.getValue()); group3[c][0] = entry.getKey(); group3[c][1] = entry.getValue(); c++; } System.out.println("map.size()为：" + map.size() + ",c为：" + c + "，group3数组的长度为：" + group3.length); System.out.println("----------------------------------------------------"); for(int n = 0; n < group3.length; n++) { System.out.println("key = " + group3[n][0] + " and value = " + group3[n][1]); } } }

输出结果为：

第一种:通过Map.keySet()遍历map1的key和value key = 012013012013 and value = 张三 key = 012013012014 and value = 张四 map1.size()为：2,a为：2，group1数组的长度为：2 ---------------------------------------------------- key = 012013012013 and value = 张三 key = 012013012014 and value = 张四 第二种:通过Map.entrySet()使用iterator()遍历map2的key和value key = 112013012014 and value = 李四 key = 112013012013 and value = 李三 map2.size()为：2,b为：2，group2数组的长度为：2 ---------------------------------------------------- key = 112013012014 and value = 李四 key = 112013012013 and value = 李三 第三种:通过Map.entrySet()遍历map的key和value key = 112013012014 and value = 李四 key = 112013012013 and value = 李三 key = 012013012013 and value = 张三 key = 012013012014 and value = 张四 map.size()为：4,c为：4，group3数组的长度为：4 ---------------------------------------------------- key = 112013012014 and value = 李四 key = 112013012013 and value = 李三 key = 012013012013 and value = 张三 key = 012013012014 and value = 张四

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