Untitled

import android.Manifest;
import android.content.DialogInterface;
import android.content.pm.PackageManager;
import android.os.Build;
import android.os.Bundle;
import android.view.View;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;

public class YourActivity extends AppCompatActivity {

    private static final int STORAGE_PERMISSION_REQUEST_CODE = 1;

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

        findViewById(R.id.yourButton).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                requestStoragePermission();
            }
        });
    }

    private void requestStoragePermission() {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            if (ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE)
                    == PackageManager.PERMISSION_GRANTED) {
                // Permission already granted
                showToast("Storage permission already granted");
            } else {
                // Show a custom dialog to request permission
                showPermissionDialog();
            }
        }
    }

    private void showPermissionDialog() {
        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setTitle("File Access Permission")
                .setMessage("This app requires access to your files. Grant permission?")
                .setPositiveButton("Grant", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        // Request storage permission
                        ActivityCompat.requestPermissions(YourActivity.this,
                                new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},
                                STORAGE_PERMISSION_REQUEST_CODE);
                    }
                })
                .setNegativeButton("Deny", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        showToast("Permission Denied");
                    }
                })
                .show();
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        if (requestCode == STORAGE_PERMISSION_REQUEST_CODE) {
            if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                showToast("Storage permission granted");
            } else {
                showToast("Storage permission denied");
            }
        }
    }

    private void showToast(String message) {
        Toast.makeText(this, message, Toast.LENGTH_SHORT).show();
    }
}