java 遍历Map及Map转化为二维数组的实例

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

如有疑问请留言或者到本站社区交流讨论，大家共同进步，感谢阅读，希望能帮助到大家，谢谢大家对本站的支持！