How to implement onClick event individual child on gridview-CodePudding

Firstly, I have seen a bunch of resources regarding this, but none of them helpful because they are using viewholder. But I'm using only adapter class. That's for, I want to know how to implement onClick event on the adapter class.

MainActivity.java

package com.sakibxhossain.gridlayout_practice;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.widget.GridView;

import com.sakibxhossain.gridlayout_practice.helper.Main_Adapter;

import java.util.ArrayList;
import java.util.HashMap;

public class MainActivity extends AppCompatActivity {

    int[] itemsImage = new int[] {
            R.drawable.logo, R.drawable.logo,
            R.drawable.logo, R.drawable.logo,
            R.drawable.logo, R.drawable.logo,
            R.drawable.logo, R.drawable.logo,
            R.drawable.logo
    };

    String[] itemTitle = new String[]{
            "Sorting", "Searching",
            "Stack & Queue", "Tree",
            "Graph", "Dynamic",
            "Greedy", "String",
            "Hashing"
    };

    String[] itemDifficulty = new String[]{
            "Easy",
            "Easy",
            "Easy",
            "Medium",
            "Hard",
            "Hard",
            "Hard",
            "Hard",
            "Medium"
    };

    GridView gridView;
    Main_Adapter adapter;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        gridView = findViewById(R.id.grid_view);

        adapter = new Main_Adapter(this, itemsImage, itemTitle, itemDifficulty);
        gridView.setAdapter(adapter);
    }
}

Main_Adapter.Java

package com.sakibxhossain.gridlayout_practice.helper;

import android.annotation.SuppressLint;
import android.content.Context;
import android.graphics.Color;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.Switch;
import android.widget.TextView;
import com.sakibxhossain.gridlayout_practice.R;

import java.util.Objects;

public class Main_Adapter extends BaseAdapter {
    Context context;
    int[] item_image;
    String[] item_Title;
    String[] item_Difficulty;

    public Main_Adapter(Context context, int[] item_image, String[] item_Title, String[] item_Difficulty) {
        this.context = context;
        this.item_image = item_image;
        this.item_Title = item_Title;
        this.item_Difficulty = item_Difficulty;
    }

    @Override
    public int getCount() {
        return item_Difficulty.length;
    }

    @Override
    public Object getItem(int position) {
        return null;
    }

    @Override
    public long getItemId(int position) {
        return 0;
    }

    @SuppressLint("InflateParams")
    @Override
    public View getView(int position, View view, ViewGroup viewGroup) {

        if(view == null){
            LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            view = inflater.inflate(R.layout.item,null);
        }

        ImageView item_image_assign = view.findViewById(R.id.item_image);
        TextView item_Title_assign = view.findViewById(R.id.item_name);
        TextView item_difficulty_assign = view.findViewById(R.id.item_difficulty_name);

        item_image_assign.setImageResource(item_image[position]);
        item_Title_assign.setText(item_Title[position]);
        item_difficulty_assign.setText(item_Difficulty[position]);

        if (Objects.equals(item_Difficulty[position], "Hard")) {
            item_difficulty_assign.setTextColor(Color.parseColor("#E91E63"));
        }else if(Objects.equals(item_Difficulty[position], "Medium")){
            item_difficulty_assign.setTextColor(Color.parseColor("#AA00FF"));
        }

        return view;
    }
}

Is it possible to do this.

What I try: I try to implement onClick event each individual child on gridview using an adapter class. But every one explaining with viewholder.

What I expect: I want to know if it is possible to implement the onClick event on the adapter class. If possible, then how to do this?

CodePudding user response：

You need to use Interface to achieve your needs :

1 - Create an Interface e.g. ClickListener :

public interface ClickListener {
    void onItemClicked(int position);
}

2 - Add it to your Adapter :

public class Main_Adapter extends BaseAdapter {
    Context context;
    int[] item_image;
    String[] item_Title;
    String[] item_Difficulty;
    private ClickListener clickListener;

    public Main_Adapter(Context context, int[] item_image, String[] item_Title, String[] item_Difficulty, ClickListener clickListener) {
        this.context = context;
        this.item_image = item_image;
        this.item_Title = item_Title;
        this.item_Difficulty = item_Difficulty;
        this.clickListener = clickListener;
    }

    @Override
    public int getCount() {
        return item_Difficulty.length;
    }

    @Override
    public Object getItem(int position) {
        return null;
    }

    @Override
    public long getItemId(int position) {
        return 0;
    }

    @SuppressLint("InflateParams")
    @Override
    public View getView(int position, View view, ViewGroup viewGroup) {
    
    if(view == null){
        LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        view = inflater.inflate(R.layout.item,null);
    }

    ImageView item_image_assign = view.findViewById(R.id.item_image);
    TextView item_Title_assign = view.findViewById(R.id.item_name);
    TextView item_difficulty_assign = view.findViewById(R.id.item_difficulty_name);
    CardView cardView = view.findViewById(R.id.cardView);
    item_image_assign.setImageResource(item_image[position]);
    item_Title_assign.setText(item_Title[position]);
    item_difficulty_assign.setText(item_Difficulty[position]);

    if (Objects.equals(item_Difficulty[position], "Hard")) {
        item_difficulty_assign.setTextColor(Color.parseColor("#E91E63"));
    }else if(Objects.equals(item_Difficulty[position], "Medium")){
        item_difficulty_assign.setTextColor(Color.parseColor("#AA00FF"));
    }
    cardView.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            clickListener.onItemClicked(position);
        }
    });
}

3 - Now call it from your MainActivity :

public class MainActivity extends AppCompatActivity {

    int[] itemsImage = new int[] {
            R.drawable.logo, R.drawable.logo,
            R.drawable.logo, R.drawable.logo,
            R.drawable.logo, R.drawable.logo,
            R.drawable.logo, R.drawable.logo,
            R.drawable.logo
    };

    String[] itemTitle = new String[]{
            "Sorting", "Searching",
            "Stack & Queue", "Tree",
            "Graph", "Dynamic",
            "Greedy", "String",
            "Hashing"
    };

    String[] itemDifficulty = new String[]{
            "Easy",
            "Easy",
            "Easy",
            "Medium",
            "Hard",
            "Hard",
            "Hard",
            "Hard",
            "Medium"
    };

    GridView gridView;
    Main_Adapter adapter;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        gridView = findViewById(R.id.grid_view);

        adapter = new Main_Adapter(this, itemsImage, itemTitle, itemDifficulty, new ClickListener() {
            @Override
            public void onItemClicked(int position) {
                Toast.makeText(MainActivity.this, "Item Clicked : " position, Toast.LENGTH_SHORT).show();
            }
        });
        gridView.setAdapter(adapter);
    }
}