将Hashmap放入Arraylist <HashMap>

Question

I'm new at android. I trying to get the data from Database and put it into HashMap . But I got a little problem here. I got an error when I try to put the data that I get.

I put a comment on the error line in my code. You can check it below

Here's my class

private static final String TAG_ITEM_NAME = "item_name";
// Hashmap for ListView
ArrayList<HashMap<String, String>> searchlist;

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    setContentView(R.layout.search);

    searchlist = new ArrayList<HashMap<String, String>>();

    Intent search = getIntent();
    String searchResult = search.getStringExtra("TAG_SEARCH");
    DatabaseHandler db = new DatabaseHandler(

    List <AllItem> allItems = new ArrayList<AllItem>();

    allItems = db.getAllSearchResult(searchResult);

    HashMap<String, AllItem> all_Items = new HashMap<String, AllItem>();

    for(AllItem cn : allItems) {    


        String item_name = cn.getItem_name();
        //AllItem item_name = all_Items.put(cn.getItem_name(), cn);

        all_Items.put(TAG_ITEM_NAME,item_name);  // I got error here
    }

    searchlist.add(all_Items);

    ListAdapter adapter = new SimpleAdapter(
            Search.this, searchlist,
            R.layout.searchlayout, new String[] {TAG_ITEM_NAME}, 
            new int[] { R.id.category_name}
            );

 // Assign adapter to ListView
    listview.setAdapter(adapter);

}

The error said The Method put(String, Allitem) int type Hashmap<String,Allitem> is not applicable for the argument (String, String)

How to fix this error? Thanks before :D

Answer 1

all_items takes a String and an AllItem , but you are placing two String s into it in this line:

// TAG_ITEM_NAME is a String and item_name is also a String
all_Items.put(TAG_ITEM_NAME,item_name);

Answer 2

You try to put in the map as a value string but you map expect as a value AllItem, so you must modify your code in this way:

for(AllItem cn : allItems) {    
    String item_name = cn.getItem_name();
    all_Items.put(item_name , cn );
}

This code will add your class object to the map with the key which equals to your object name.

Answer 3

Your HashMap is as follows:

HashMap<String, AllItem> all_Items = new HashMap<String, AllItem>();

This means it has String keys and AllItem values. You can put a AllItem object inside this HashMap .

When you write

all_Items.put(TAG_ITEM_NAME,item_name);  // I got error here

you are putting a String inside the HashMap hence it is giving error.

You should be doing:

 all_Items.put(TAG_ITEM_NAME,cn);

Answer 4

Your hashmap is <String, Allitem> . While you try to put <String, String> in it.

all_Items.put(TAG_ITEM_NAME, item_name);

should be changed to

all_Items.put(TAG_ITEM_NAME, cn);

Hope you got the difference.

Answer 5

all_Items is defined as a hashmap to contain <String, AllItem> key value pairs as defined here:

HashMap<String, AllItem> all_Items = new HashMap<String, AllItem>();

but you are trying to push <String,String> key value pair into your all_Items hashmap :

all_Items.put(TAG_ITEM_NAME,item_name);  // I got error here

It seems you want to push the AllItem object against its item_name , which can be done as:

all_Items.put(item_name, cn); 

Answer 6

I dont see connection in the code but using the given information, your error probably is related to your searchlist variable in your code.

change this:

ArrayList<HashMap<String, String>> searchlist;

to this:

ArrayList<HashMap<String, AllItem>> searchlist;

Answer 7

it's because you declared HashMap<String, AllItem> and you try to put all_Items.put(TAG_ITEM_NAME,item_name); which would probably be HashMap<String, String>() all_Items.put(TAG_ITEM_NAME,item_name); which would probably be HashMap<String, String>() .