I have a "Map<String, Object> values". How can I parse this map so that I get a following string at the end?

String string= "key1 = value1, key2 = value2, key3 = value3, ..."

It is important that as soon as a value contains a string then it should be provided with single quotes.

Thanks in advance

UPDATE 1

I need to expand my question.

So I need the string for a sql query. But the values which are strings have to be populated with SingleQuotes.

I show you my PostRequest method:

 @Transactional
    @PostMapping(value = "/config/test/{tableName}/{schemaName}")
    public Map<String, Object> postValue(@RequestBody Map<String, Object> values, @PathVariable("tableName") String tableName,
            @PathVariable("schemaName") String schemaName) {
        String keyString = "";
        String valueString = "";

        Set<String> keySet = values.keySet();

        for (String key : keySet) {

            // add comma after first key-value pair only.
            if (keyString.length() > 0) {
                keyString  = ",";
                valueString  = ",";
            }

            keyString  = key;

            Object valueObj = values.get(key);
            if (valueObj instanceof String) {
                valueString = valueString   "'"   valueObj.toString()   "'";
                ;
            } else if (valueObj instanceof Integer) {
                Integer valueInt = (Integer) valueObj;
                valueString = valueString   valueInt;
            } else if (valueObj instanceof Double) {
                Double valueDouble = (Double) valueObj;
                valueString = valueString   valueDouble;
            }
        }
        final String sql = "INSERT INTO "   schemaName   "."   tableName   "("   keyString   ") VALUES("   valueString   ")";
        final Query query = em.createNativeQuery(sql);
        query.executeUpdate();
        return values;
    }

Here I get 2 strings. One for the keys and one for the values.

But now I want to get only one string to change data in the database.

Here is my first try.

@Transactional
    @PutMapping(value = "/config/test/{tableName}/{schemaName}/{id}")
    public Map<String, Object> updateValue(@RequestBody Map<String, Object> values, @PathVariable("tableName") String tableName,
            @PathVariable("schemaName") String schemaName, @PathVariable("id") String id) {
        String keyString = "";
        String valueString = "";
        String updateString = "";

        Set<String> keySet = values.keySet();

        for (String key : keySet) {

            if (keyString.length() > 0) {
                keyString  = "=";
                updateString  = ",";
            }

            updateString  = key;

            Object valueObj = values.get(key);
            if (valueObj instanceof String) {
                valueString = valueString   "'"   valueObj.toString()   "'";
                ;
            } else if (valueObj instanceof Integer) {
                Integer valueInt = (Integer) valueObj;
                valueString = valueString   valueInt;
            } else if (valueObj instanceof Double) {
                Double valueDouble = (Double) valueObj;
                valueString = valueString   valueDouble;
            }
        }

        final String sql = "UPDATE "   schemaName   "."   tableName   " SET "   updateString   " WHERE ID ="   id;
        final Query query = em.createNativeQuery(sql);
        query.executeUpdate();
        return values;
    }

P.S. Yes I am using Spring Boot rather than Java, but I am trying to solve this without getting more dependencies.

CodePudding user response：

I just use Guava, probably toStringHelper can help with this, for example

System.out.println(MoreObjects.toStringHelper("className").add("name","hoyt").add("age",11).add("job","writeBugs")
                .add("nullField", null)
                .omitNullValues().toString());

// this is the print
// className{name=hoyt, age=11, job=writeBugs} 

you can iter through the map, and call add method, the return of the add method is the Guava object itself, so you can chain it.

MoreObjects.toStringHelper tsh = MoreObjects.toStringHelper("className")
foreach(Entry e : map){
    // add single quote if the value is a String,
    Object value = e.getValue();
    String valueString = value instanceof String?"'"   value.toString()   "'": value.toString();
    tsh.add(e.getKey().toString(), valueString);
}
// System.out.println(tsh.toString())

CodePudding user response：

Refer the following example, you need to override the toString() Method

class TestObject {
  int val;

  public TestObject(int val){
    this.val = val;
  }

  public String toString(){
   return ""   this.val;
  }

}

Map<String, TestObject> map = new HashMap<>();
map.put("First Object", new TestObject(1));
map.put("Second Object", new TestObject(2));
map.put("Third Object", new TestObject(3));

map.toString() ==> {Third Object=3, First Object=1, Second Object=2} // on printing map object

Further you can edit map.toString() output as follows

map.toString().replace("{", "").replace("}", "");

CodePudding user response：

Stream based solution:

final Map<String, Object> values = Map.of("key1", "value1", "key2", "value2", "key3", "value3");
final var string = values.entrySet().stream().map(x -> x.getKey()   " = "   x.getValue()).collect(Collectors.joining(", "));
System.out.println(string);  // key1 = value1, key2 = value2, key3 = value3

Or you can simply use StringBuilder and iterate your Map.

CodePudding user response：

import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.stream.Collectors;

public class ParseMap {

    public static String getMapAsCustomString(Map<String, Object> map) {
        return map.entrySet()
                .stream()
                .map(ParseMap::formatEntry)
                .collect(Collectors.joining(", "));
    }

    public static String formatEntry(Entry<String, Object> entry) {
        Object value = entry.getValue();
        return entry.getKey()   "="   (value instanceof String ? "'"   value   "'" : value.toString());
    }

}

class Test {
    public static void main(String[] args) {
        Map<String, Object> map = new HashMap<>();
        map.put("key1", 1);
        map.put("key2", "Two");
        map.put("key3", 7L);

        String string = ParseMap.getMapAsCustomString(map);
        System.out.println(string);
    }
}