如何获取 HashMap<String, Object> 中特定键值的子集 initialMap = new HashMap<String, Object>()

Question

我有一个

HashMap<String, Object> initialMap = new HashMap<String, Object>();

其中我以这种方式设置了键的字符串值，

error=[e1, e2, e3, e4, e5, e6],[e7, e8, e9, e10, e11, e12],[e13, e14 ,e15, e16, e17, e18],[e19, e20, e21, e22, e23, e24],[e25, e26, e27, e28, e29, e30], status=[s1, s2, s3, s4, s5, s6],[s7, s8 s9, s10, s11, s12],[s13, s14 ,s15, s16, s17, s18],[s19, s20, s21, s22, s23, s24],[s25, s26, s27, s28, s29, s30], data=[[d1, d2, d3, d4, d5, d6],[d7, d8, d9, d10, d11, d12],[d13, d14 ,d15, d16, d17, d18],[d19, d20, d21, d22, d23, d24],[d25, d26, d27, d28, d29, d30]], warning=[w1, w2, w3, w4, w5, w6],[w7, w8, w9, w10, w11, w12],[w13, w14 ,w15, w16, w17, w18],[w19, w20, w21, w22, w23, w24],[w25, w26, w27, w28, w29, w30]}

所以，这里有一个名为 error 的键，

下面有这 5 组字符串值。

[e1, e2, e3, e4, e5, e6],[e7, e8, e9, e10, e11, e12],[e13, e14 ,e15, e16, e17, e18],[e19, e20, e21, e22, e23, e24],[e25, e26, e27, e28, e29, e30].

我不需要一个键的所有这 5 个设置值，但我需要使用开始和结束限制，即每个键的值的子集。

假设我的 startLimit=2 和 endLimit=4 那么我应该只得到 2,3,4 组键错误值，

[e7, e8, e9, e10, e11, e12],[e13, e14 ,e15, e16, e17, e18],[e19, e20, e21, e22, e23, e24]

同样需要对所有其他 3 个键重复。

我试过这种方法，但它总是给我一个特定键的所有值。

有什么方法可以获取哈希图中特定键值的子集吗？

这是我试过的代码，

public class MapTest {
        HashMap<String, Object> finalMap = new HashMap<String, Object>();
        int startLimit = 2;
        int endLimit = 4;

        public static void main(String[] args) {
            MapTest mm = new MapTest();
            mm.getData();
        }
        public void getData()
        {
            HashMap<String, Object> initialMap = new HashMap<String, Object>();
            initialMap.put("status","[s1, s2, s3, s4, s5, s6],[s7, s8 s9, s10, s11, s12],[s13, s14 ,s15, s16, s17, s18],[s19, s20, s21, s22, s23, s24],[s25, s26, s27, s28, s29, s30]");
            initialMap.put("data","[[d1, d2, d3, d4, d5, d6],[d7, d8, d9, d10, d11, d12],[d13, d14 ,d15, d16, d17, d18],[d19, d20, d21, d22, d23, d24],[d25, d26, d27, d28, d29, d30]]");
            initialMap.put("warning","[w1, w2, w3, w4, w5, w6],[w7, w8, w9, w10, w11, w12],[w13, w14 ,w15, w16, w17, w18],[w19, w20, w21, w22, w23, w24],[w25, w26, w27, w28, w29, w30]");
            initialMap.put("error","[e1, e2, e3, e4, e5, e6],[e7, e8, e9, e10, e11, e12],[e13, e14 ,e15, e16, e17, e18],[e19, e20, e21, e22, e23, e24],[e25, e26, e27, e28, e29, e30]");

            Set<Entry<String, Object>> entries = initialMap .entrySet();
            for (Iterator<Entry<String, Object>> i = entries.iterator(); i.hasNext(); ) {
                Entry e = (Entry) i.next();
                if(e.getKey().equals("error"))
                {   
                    Object errValue = initialMap.get(e.getKey());
                    //System.out.println("errValue" + errValue);
                    finalMap.put(e.getKey().toString(), errValue);
                }
                if(e.getKey().equals("data"))
                {   
                    Object errValue = initialMap.get(e.getKey());
                    //System.out.println("errValue" + errValue);
                    finalMap.put(e.getKey().toString(), errValue);
                }
                else if(e.getKey().equals("warning"))
                {   
                    Object errValue = initialMap.get(e.getKey());
                    //System.out.println("errValue" + errValue);
                    finalMap.put(e.getKey().toString(), errValue);
                }
                if(e.getKey().equals("status"))
                {   
                    Object errValue = initialMap.get(e.getKey());
                    //System.out.println("errValue" + errValue);
                    finalMap.put(e.getKey().toString(), errValue);
                }
            }
            if(startLimit == 2 && endLimit == 4)
                System.out.println("final map after limiting the data " + finalMap);
        } 
    }

我正在从上面的程序中以这种方式获取一个键的所有 5 对值，

限制数据后的最终地图

{error=[e1, e2, e3, e4, e5, e6],[e7, e8, e9, e10, e11, e12],[e13, e14 ,e15, e16, e17, e18],[e19, e20, e21, e22, e23, e24],[e25, e26, e27, e28, e29, e30], status=[s1, s2, s3, s4, s5, s6],[s7, s8 s9, s10, s11, s12],[s13, s14 ,s15, s16, s17, s18],[s19, s20, s21, s22, s23, s24],[s25, s26, s27, s28, s29, s30], data=[[d1, d2, d3, d4, d5, d6],[d7, d8, d9, d10, d11, d12],[d13, d14 ,d15, d16, d17, d18],[d19, d20, d21, d22, d23, d24],[d25, d26, d27, d28, d29, d30]], warning=[w1, w2, w3, w4, w5, w6],[w7, w8, w9, w10, w11, w12],[w13, w14 ,w15, w16, w17, w18],[w19, w20, w21, w22, w23, w24],[w25, w26, w27, w28, w29, w30]}

但是我需要这样，因为我的限制是 2 到 4 对，

限制数据后的最终地图{error=[e7, e8, e9, e10, e11, e12],[e13, e14 ,e15, e16, e17, e18],[e19, e20, e21, e22, e23, e24], status=[s7, s8 s9, s10, s11, s12],[s13, s14 ,s15, s16, s17, s18],[s19, s20, s21, s22, s23, s24], data=[[d7, d8, d9, d10, d11, d12],[d13, d14 ,d15, d16, d17, d18],[d19, d20, d21, d22, d23, d24]], warning=[w7, w8, w9, w10, w11, w12],[w13, w14 ,w15, w16, w17, w18],[w19, w20, w21, w22, w23, w24]}

谁能帮我解决这个问题？

谢谢

Answer 1

我在您的代码中发现了 2 个大问题：

startLimit 和 endLimit 不用于过滤从 initialMap 中提取的数据，但它们只是在 i 值上进行测试；您的代码只需将 key/value 从 initialMap 复制到 finalMap 然后打印 finalMap 如果两个限制设置为 2 和 4（它们只是标志来决定是否打印或不是
initialMap 中的每个键都与 String（不是 Object 或 List）关联，所以我看到的唯一方法是将 [=39= 分开] 正在玩逗号..但我不确定这是否是您代码的目标

我建议您将地图值更改为 List<String> 并重新考虑 getData 的逻辑。

public static void main(String[] args) {
    int startLimit = 2;
    int endLimit = 4;

    HashMap<String, List<String>> finalMap = new HashMap<>();
    HashMap<String, List<String>> initialMap = new HashMap<>();

    List<String> sList = Arrays.asList("[s1, s2, s3, s4, s5, s6]", "[s7, s8, s9, s10, s11, s12]", "[s13, s14 ,s15, s16, s17, s18]", "[s19, s20, s21, s22, s23, s24]", "[s25, s26, s27, s28, s29, s30]");
    List<String> dList = Arrays.asList("[d1, d2, d3, d4, d5, d6]", "[d7, d8, d9, d10, d11, d12]", "[d13, d14 ,d15, d16, d17, d18]", "[d19, d20, d21, d22, d23, d24]", "[d25, d26, d27, d28, d29, d30]");
    List<String> wList = Arrays.asList("[w1, w2, w3, w4, w5, w6]", "[w7, w8, w9, w10, w11, w12]", "[w13, w14 ,w15, w16, w17, w18]", "[w19, w20, w21, w22, w23, w24]", "[w25, w26, w27, w28, w29, w30]");
    List<String> eList = Arrays.asList("[e1, e2, e3, e4, e5, e6]", "[e7, e8, e9, e10, e11, e12]", "[e13, e14 ,e15, e16, e17, e18]", "[e19, e20, e21, e22, e23, e24]", "[e25, e26, e27, e28, e29, e30]");

    initialMap.put("status", sList);
    initialMap.put("data", dList);
    initialMap.put("warning", wList);
    initialMap.put("error", eList);

    Iterator<Entry<String, List<String>>> i = initialMap.entrySet().iterator();
    Entry<String, List<String>> e = null;
    List<String> eValue = null;
    while (i.hasNext()) {
        e = i.next();
        eValue = e.getValue();
        finalMap.put(e.getKey(), eValue.subList(startLimit, endLimit));
    }
    System.out.println("final map after limiting the data " + finalMap);
}

编辑：如果地图值不能是List<String>你可以按如下方式做

public static void main(String[] args) {
    int startLimit = 2;
    int endLimit = 4;
    String objectSeparator = "],";

    HashMap<String, String> finalMap = new HashMap<>();
    HashMap<String, String> initialMap = new HashMap<>();

    String sList = "[s1, s2, s3, s4, s5, s6],[s7, s8 s9, s10, s11, s12],[s13, s14 ,s15, s16, s17, s18],[s19, s20, s21, s22, s23, s24],[s25, s26, s27, s28, s29, s30]";
    String dList = "[[d1, d2, d3, d4, d5, d6],[d7, d8, d9, d10, d11, d12],[d13, d14 ,d15, d16, d17, d18],[d19, d20, d21, d22, d23, d24],[d25, d26, d27, d28, d29, d30]]";
    String wList = "[w1, w2, w3, w4, w5, w6],[w7, w8, w9, w10, w11, w12],[w13, w14 ,w15, w16, w17, w18],[w19, w20, w21, w22, w23, w24],[w25, w26, w27, w28, w29, w30]";
    String eList = "[e1, e2, e3, e4, e5, e6],[e7, e8, e9, e10, e11, e12],[e13, e14 ,e15, e16, e17, e18],[e19, e20, e21, e22, e23, e24],[e25, e26, e27, e28, e29, e30]";

    initialMap.put("status", sList);
    initialMap.put("data", dList);
    initialMap.put("warning", wList);
    initialMap.put("error", eList);

    Iterator<Entry<String, String>> it = initialMap.entrySet().iterator();
    Entry<String, String> e = null;
    String eValue = null;
    String[] splitted = null;
    while (it.hasNext()) {
        e = it.next();
        eValue = e.getValue();

        // Split each "square bracket object" in a separate string 
        splitted = eValue.split(objectSeparator);

        // Create a new string containing only objects with index between limits
        String limited = "";
        for(int idx = startLimit-1; idx <= endLimit-1; idx++)
            limited += (splitted[idx] + objectSeparator);

        // Remove trailing comma added inside for loop
        limited = limited.substring(0, limited.lastIndexOf(","));

        finalMap.put(e.getKey(), limited);
    }
    System.out.println("final map after limiting the data " + finalMap);
}

Answer 2

注意： 我假设与 "data" 键关联的值与其他值具有相同的结构（没有额外的括号），如果不是这样的话然后算法变得有点复杂。

我在 JDK 6.

之上使用了 guava and commons-lang3

HashMap<String, Object> finalMap = Maps.newHashMap(Maps.transformValues(initialMap, new Function<Object, Object>() {
    public Object apply(Object input) {
        String inputAsString = (String) input;
        String trimmedInput = inputAsString.replaceAll("^\[+", "").replaceAll("\]+$", "");
        int removedBraces = (inputAsString.length() - trimmedInput.length()) / 2;
        List<String> splitInput = Lists.newArrayList(Splitter.on("],[").split(trimmedInput));
        List<String> subList = splitInput.subList(startLimit - 1, endLimit);
        return StringUtils.repeat('[', removedBraces) + Joiner.on("],[").join(subList)
        + StringUtils.repeat(']', removedBraces);
    }
}));

简而言之，这段代码创建了一个新地图，其中新地图中的每个值都是通过使用以下算法转换初始值来构建的：

去掉开头的“[”和结尾的“]”
用“],[”字符串分割
获取结果列表的子列表（从 startLimit - 1 到 endLimit）
使用“],[”将列表重新组合成一个字符串，向后添加初始前导“[”和尾随“]”

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