java arraylist hashmap如何打印[关闭]答案

【问题标题】：java arraylist hashmap how to println [closed]java arraylist hashmap如何打印[关闭]
【发布时间】：2013-02-04 07:56:04
【问题描述】：

如何打印？？

LINE1“A”=1，“B”=1，“C”=3
LINE2“A”=1，“B”=1，“C”=2
LINE3“A”=1，“B”=11，“C”=2
LINE4“A”=1，“B”=2，“C”=2
LINE5“A”=1，“B”=1，“C”=11

    ArrayList mylist = new ArrayList();

    Map<String,Integer> mMap = new HashMap<String,Integer>();
    mMap.put("A",1);
    mMap.put("B",1);
    mMap.put("C",3);
    mylist.add(mMap); 

    mMap = new HashMap<String,Integer>();
    mMap.put("A",1);
    mMap.put("B",1);
    mMap.put("C",2);
    mylist.add(mMap); 

    mMap = new HashMap<String,Integer>();
    mMap.put("A",1);
    mMap.put("B",11);
    mMap.put("C",2);
    mylist.add(mMap);

    mMap = new HashMap<String,Integer>();
    mMap.put("A",1);
    mMap.put("B",2);
    mMap.put("C",2);
    mylist.add(mMap);

    mMap = new HashMap<String,Integer>();
    mMap.put("A",1);
    mMap.put("B",1);
    mMap.put("C",11);       
    mylist.add(mMap);

【问题讨论】：

标签： java map arraylist hashmap

【解决方案1】：

试试这个 -

for (Map<String, Integer> map : mylist) {
    for (Entry<String, Integer> entry : map.entrySet()) {
        System.out.print("\""+entry.getKey()+"\"="+entry.getValue()+" ");
    }
    System.out.println("\n");
}

输出-

“A”=1 “B”=1 “C”=2

"A"=1 "B"=1 "C"=3

“A”=1 “B”=1 “C”=11

“A”=1 “B”=2 “C”=2

"A"=1 "B"=11 "C"=2

【讨论】：

【解决方案2】：

int counter = 1;
StringBuffer buffer = new StringBuffer();

for (Map<String,Integer> map : mylist) {
    buffer.append("LINE");
    buffer.append(counter++);

    for (Entry<String, Integer> entry : map.entrySet()) {
        String key = entry.getKey();
        Object value = entry.getValue();

        buffer.append(" \"");
        buffer.append(key);
        buffer.append("\"=");
        buffer.append(value);
        buffer.append(", ");
    }

    String s = buffer.toString().trim().substring(0, buffer.length() - 2);
    System.out.println(s);
    buffer.delete(0, buffer.length());
}

只需将其放在代码的末尾即可..

顺便说一句，将您的第一行更改为

ArrayList<Map<String,Integer>> mylist = new ArrayList<Map<String, Integer>>();

这将导致

LINE1 "A"=1, "B"=1, "C"=3
LINE2 "A"=1, "B"=1, "C"=2
LINE3 "A"=1, "B"=11, "C"=2
LINE4 "A"=1, "B"=2, "C"=2
LINE5 "A"=1, "B"=1, "C"=11

编辑：在行号后添加空格

【讨论】：

【解决方案3】：

略有不同的解决方案：

   final String A = "A";
   final String B = "B";
   final String C = "C"; 
   for (int i = 0; i < mylist.size(); i++) {
       Map<String, Integer> map = mylist.get(i);
       System.out.println(String.format("LINE%d \"A\"=%d,\"B\"=%d,\"C\"=%d", i, map.get(A), map.get(B), map.get(C)));
   }

【讨论】：