Die Anleitung zu Android ListView

package org.o7planning.simplelistview;

import java.io.Serializable;

public class UserAccount implements Serializable {

    private String userName;
    private String userType;

    private boolean active;

    public UserAccount(String userName, String userType)  {
        this.userName= userName;
        this.userType = userType;
        this.active= true;
    }

    public UserAccount(String userName, String userType, boolean active)  {
        this.userName= userName;
        this.userType = userType;
        this.active= active;
    }

    public String getUserType() {
        return userType;
    }

    public void setUserType(String userType) {
        this.userType = userType;
    }

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public boolean isActive() {
        return active;
    }

    public void setActive(boolean active) {
        this.active = active;
    }

    @Override
    public String toString() {
        return this.userName +" ("+ this.userType+")";
    }

}

package org.o7planning.simplelistview;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.widget.ArrayAdapter;
import android.widget.ListView;

public class MainActivity extends AppCompatActivity {

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

        ListView listView = (ListView)findViewById(R.id.listView);

        //

        UserAccount tom = new UserAccount("Tom","admin");
        UserAccount jerry = new UserAccount("Jerry","user");
        UserAccount donald = new UserAccount("Donald","guest", false);

        UserAccount[] users = new UserAccount[]{tom,jerry, donald};


        // android.R.layout.simple_list_item_1 is a constant predefined layout of Android.
        // used to create a ListView with simple ListItem (Only one TextView).

        ArrayAdapter<UserAccount> arrayAdapter
                = new ArrayAdapter<UserAccount>(this, android.R.layout.simple_list_item_1 , users);

        listView.setAdapter(arrayAdapter);
    }


}

package org.o7planning.customlistview;

public class Country {

    private String countryName;

    // Image name (Without extension)
    private String flagName;
    private int population;

    public Country(String countryName, String flagName, int population) {
        this.countryName= countryName;
        this.flagName= flagName;
        this.population= population;
    }

    public int getPopulation() {
        return population;
    }

    public void setPopulation(int population) {
        this.population = population;
    }

    public String getCountryName() {
        return countryName;
    }

    public void setCountryName(String countryName) {
        this.countryName = countryName;
    }

    public String getFlagName() {
        return flagName;
    }

    public void setFlagName(String flagName) {
        this.flagName = flagName;
    }

    @Override
    public String toString()  {
        return this.countryName+" (Population: "+ this.population+")";
    }
}

package org.o7planning.customlistview;

import android.content.Context;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;
import java.util.List;

public class CustomListAdapter  extends BaseAdapter {

    private List<Country> listData;
    private LayoutInflater layoutInflater;
    private Context context;

    public CustomListAdapter(Context aContext,  List<Country> listData) {
        this.context = aContext;
        this.listData = listData;
        layoutInflater = LayoutInflater.from(aContext);
    }

    @Override
    public int getCount() {
        return listData.size();
    }

    @Override
    public Object getItem(int position) {
        return listData.get(position);
    }

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

    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder holder;
        if (convertView == null) {
            convertView = layoutInflater.inflate(R.layout.list_item_layout, null);
            holder = new ViewHolder();
            holder.flagView = (ImageView) convertView.findViewById(R.id.imageView_flag);
            holder.countryNameView = (TextView) convertView.findViewById(R.id.textView_countryName);
            holder.populationView = (TextView) convertView.findViewById(R.id.textView_population);
            convertView.setTag(holder);
        } else {
            holder = (ViewHolder) convertView.getTag();
        }

        Country country = this.listData.get(position);
        holder.countryNameView.setText(country.getCountryName());
        holder.populationView.setText("Population: " + country.getPopulation());

        int imageId = this.getMipmapResIdByName(country.getFlagName());

        holder.flagView.setImageResource(imageId);

        return convertView;
    }

    // Find Image ID corresponding to the name of the image (in the directory mipmap).
    public int getMipmapResIdByName(String resName)  {
        String pkgName = context.getPackageName();
        // Return 0 if not found.
        int resID = context.getResources().getIdentifier(resName , "mipmap", pkgName);
        Log.i("CustomListView", "Res Name: "+ resName+"==> Res ID = "+ resID);
        return resID;
    }

    static class ViewHolder {
        ImageView flagView;
        TextView countryNameView;
        TextView populationView;
    }

}

package org.o7planning.customlistview;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListView;
import android.widget.Toast;
import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

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


        List<Country> image_details = getListData();
        final ListView listView = (ListView) findViewById(R.id.listView);
        listView.setAdapter(new CustomListAdapter(this, image_details));

        // When the user clicks on the ListItem
        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> a, View v, int position, long id) {
                Object o = listView.getItemAtPosition(position);
                Country country = (Country) o;
                Toast.makeText(MainActivity.this, "Selected :" + " " + country, Toast.LENGTH_LONG).show();
            }
        });
    }

    private  List<Country> getListData() {
        List<Country> list = new ArrayList<Country>();
        Country vietnam = new Country("Vietnam", "vn", 98000000);
        Country usa = new Country("United States", "us", 320000000);
        Country russia = new Country("Russia", "ru", 142000000);


        list.add(vietnam);
        list.add(usa);
        list.add(russia);

        return list;
    }

}