CODEWITHSUNDEEP
javaarraylistdata-structureshashmap
user1909711
user1909711

Reputation: 39

Add values to Hashmap based on some criteria

This below code checks id exist in ArrayList or not & then add it to map.

List<Map<Object, Object>> myListOfMaps = new ArrayList<Map<Object, Object>>();
ArrayList<String> al1 = new ArrayList<String>();
al1.add("92");
al1.add("94");  
al1.add("91");  
al1.add("98");
Map<Object,Object> map = new HashMap<Object,Object>();
ArrayList<String> result = new ArrayList<String>();               
String id = "95,98,94";
for(int i=0;i<al1.size();i++)
{
    if(id.contains(al1.get(i)))
    {
        result.add("true");
        map.put("Access", true);                
    }            
    else 
    {
        result.add("false");
        map.put("Access", false);               
    }
    myListOfMaps.add(map);               

}
  for (int i = 0 ; i < myListOfMaps.size() ; i++) {
    Map<Object, Object> myMap = myListOfMaps.get(i);          
    for (Entry<Object, Object> entrySet : myMap.entrySet()) {                                
        System.out.println("Key = " + entrySet.getKey() + " , Value = " + entrySet.getValue());
    }
}          
System.out.println(result);

output

Key = Access , Value = true
Key = Access , Value = true
Key = Access , Value = true
Key = Access , Value = true
[false, true, false, true]

arraylist result is fine but mapvalues returning true only.Please help me how to add k,v to map based on condition so that mapresult looks like this [{Access=false},{Access=true},{Access=false},{Access=true}].

Upvotes: 1

Views: 1018

Answers (3)

T&#246;rpetestű
T&#246;rpetestű

Reputation: 202

This code will help you:

List<Map<String, Boolean>> myListOfMaps = new ArrayList<>();
List<String> al1 = new ArrayList<>();
al1.add("92");
al1.add("94");
al1.add("91");
al1.add("98");

String id = "95,98,94";

List<String> result = new ArrayList<>();
for (int i = 0; i < al1.size(); i++) {
    Map<String, Boolean> map = new HashMap<>();
    if (id.contains(al1.get(i))) {
        result.add("true");
        map.put("Access", true);
    } else {
        result.add("false");
        map.put("Access", false);
    }
    myListOfMaps.add(map);
}
myListOfMaps.forEach(System.out::println);
System.out.println(result);

Upvotes: 0

St&#233;phane Ammar
St&#233;phane Ammar

Reputation: 1454

You ahve to declare a new Map every time in your loop

//...
al1.add("98");
 //Map<Object,Object> map = new HashMap<Object,Object>();
ArrayList<String> result = new ArrayList<String>();               
String id = "95,98,94";
for(int i=0;i<al1.size();i++)
{
    Map<Object,Object> map = new HashMap<Object,Object>();
    if(id.contains(al1.get(i)))
    {
        result.add("true");
        map.put("Access", true);                
    }            
    else 
    {
        result.add("false");
        map.put("Access", false);               
    }
    myListOfMaps.add(map);               

}
//...

Upvotes: 0

Robert D. Mogos
Robert D. Mogos

Reputation: 910

A hashmap is a key-value data structure. The way you store items is based on the key.

This being said, if you add a key Access to the map with the value false and print the map it will show : Access: false.

If you add again Access with the value true is not going to add a new key, is going to replace the previous value so it will print Access: true

So instead of adding the key Access to the map, add the id. map.put(al1.get(i), true);

Upvotes: 1

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