Question

我试图在我的Android活动中添加一个记分板，但我无法在网上找到任何有用的东西。我无法使用谷歌排行榜，因为我必须将我的应用程序呈现给将下载代码并运行它而不是已发布的应用程序的人。我正在使用此应用程序的人向我发送了此代码，但该代码无效。如果有人在如何从头开始制作记分板方面有任何良好的联系，或者可以告诉我这段代码有什么问题我会很感激

public class Leaderboard extends AppCompatActivity {
    private ListView UsernameList;
    private ListView ScoreList;

    /** Called when the activity is first created */
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        ArrayAdapter<String> listAdapter;
        ArrayAdapter<Integer> list2Adapter;

        //Find the ListView resources
        UsernameList = (ListView) findViewById(R.id.UsernameList);
        ScoreList = (ListView) findViewById(R.id.ScoreList);

        //Create and populate the list of usernames.
        //This is where the information from the Database would need to be entered. and the String[] removed
        String[] usernames = new String[]{"Andy", "Marie", "George"};
        ArrayList<String> usernameList = new ArrayList<String>();
        usernameList.addAll(Arrays.asList(usernames));

        //Create and populate the list of scores
        //This is where the information from the Database would need to be entered. and the Integer[] removed
        Integer[] scores = new Integer[]{7, 4, 1};
        ArrayList<Integer> scoreList = new ArrayList<Integer>();
        scoreList.addAll(Arrays.asList(scores));

        //Create Array Adapter using the username list
        listAdapter = new ArrayAdapter<String>(this, R.layout.activity_row, usernameList);
        //Add more users
        listAdapter.add("Michael");
        //Set the Array Adapter as the ListView's adapter
        UsernameList.setAdapter(listAdapter);

        //Create Array Adapter using the username list
        list2Adapter = new ArrayAdapter<Integer>(this, R.layout.activity_row, scoreList);
        //Add more users
        list2Adapter.add(0);
        //Set the Array Adapter as the ListView's adapter
        ScoreList.setAdapter(list2Adapter);

    }
}

（这是发给我的排行榜的java类）

Answer 1

这是我创建的一个演示，使用sqllite数据库读取名称和分数

我称之为记分板

主要活动代码

package com.scroreboard.live.scoreboard;

import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.ListView;
import com.scroreboard.live.scoreboard.adapter.CustomListAdapter;
import com.scroreboard.live.scoreboard.model.Items;
import java.util.ArrayList;
import java.util.List;


public class MainActivity extends AppCompatActivity {

    private List<Items> itemsList = new ArrayList<Items>();
    private ListView listView;
    private CustomListAdapter adapter;

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

        SQLiteDatabase myDB = null;

        try {

            //Create a Database if doesnt exist otherwise Open It

            myDB = this.openOrCreateDatabase("leaderboard", MODE_PRIVATE, null);

            //Create table in database if it doesnt exist allready

            myDB.execSQL("CREATE TABLE IF NOT EXISTS scores (name TEXT, score TEXT);");

            //Select all rows from the table

            Cursor cursor = myDB.rawQuery("SELECT * FROM scores", null);

            //If there are no rows (data) then insert some in the table

            if (cursor != null) {
                if (cursor.getCount() == 0) {

                    myDB.execSQL("INSERT INTO scores (name, score) VALUES ('Andy', '7');");
                    myDB.execSQL("INSERT INTO scores (name, score) VALUES ('Marie', '4');");
                    myDB.execSQL("INSERT INTO scores (name, score) VALUES ('George', '1');");

                }

            }


        } catch (Exception e) {

        } finally {

            //Initialize and create a new adapter with layout named list found in activity_main layout

            listView = (ListView) findViewById(R.id.list);
            adapter = new CustomListAdapter(this, itemsList);
            listView.setAdapter(adapter);

            Cursor cursor = myDB.rawQuery("SELECT * FROM scores", null);

                if (cursor.moveToFirst()) {

                    //read all rows from the database and add to the Items array

                    while (!cursor.isAfterLast()) {

                        Items items = new Items();

                        items.setName(cursor.getString(0));
                        items.setScore(cursor.getString(1));

                        itemsList.add(items);
                        cursor.moveToNext();


                    }
                }

            //All done, so notify the adapter to populate the list using the Items Array

            adapter.notifyDataSetChanged();
            }

        }

    }

在您的项目中，右键单击（在我的情况下） com.scroreboard.live.scoreboard ，然后选择 new - ＆gt;包装就像你在图片中看到的那样

创建2个名为适配器的软件包和另一个模型

右键单击适配器，然后选择 new - ＆gt; Java类

将其命名为 CustomListAdapter

右键点击型号，然后选择 new - ＆gt; Java类

将其命名为项目

CustomListAdapter代码

package com.scroreboard.live.scoreboard.adapter;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;
import com.scroreboard.live.scoreboard.R;
import com.scroreboard.live.scoreboard.model.Items;
import java.util.List;

public class CustomListAdapter extends BaseAdapter {

    private  Context mContext;
    private LayoutInflater inflater;
    private List<Items> itemsItems;



    public CustomListAdapter(Context context, List<Items> itemsItems) {
        this.mContext = context;
        this.itemsItems = itemsItems;

    }

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

    @Override
    public Object getItem(int location) {
        return itemsItems.get(location);
    }

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

    @Override
    public View getView(int position, View scoreView, ViewGroup parent) {
        ViewHolder holder;
        if (inflater == null) {
            inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        }
        if (scoreView == null) {

            scoreView = inflater.inflate(R.layout.list_row, parent, false);
            holder = new ViewHolder();
            holder.name = (TextView) scoreView.findViewById(R.id.name);
            holder.score = (TextView) scoreView.findViewById(R.id.score);

            scoreView.setTag(holder);

        } else {
            holder = (ViewHolder) scoreView.getTag();
        }

        final Items m = itemsItems.get(position);
        holder.name.setText(m.getName());
        holder.score.setText(m.getScore());

        return scoreView;
    }

    static class ViewHolder {

        TextView name;
        TextView score;

    }

}

商品代码

package com.scroreboard.live.scoreboard.model;

public class Items {

    private String name, score;

    public Items() {
    }

    public Items(String name, String score) {

        this.name = name;
        this.score = score;

    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getScore() {
        return score;
    }

    public void setScore(String score) {
        this.score = score;
    }
}

还有更多的东西。

在main_activity布局文件或任何要添加ListView的活动布局中添加以下内容（根据需要设置样式）

<ListView
    android:id="@+id/list"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:paddingBottom="5dp"
    android:clipToPadding="false"
    android:dividerHeight="1dp"
    android:cacheColorHint="#FFFFFF"
    android:layout_marginTop="56dp"/>

最后创建另一个布局资源并将其命名为 list_row

内部的XML代码

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:background="#ffffff"
    android:paddingTop="12dp"
    android:paddingBottom="12dp"
    android:paddingRight="5dp"
    android:paddingLeft="5dp"
    android:descendantFocusability="blocksDescendants">



    <TextView
        android:id="@+id/name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:textSize="16dp"
        android:textColor="#222222"/>

    <TextView
        android:id="@+id/score"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:layout_marginRight="8dp"
        android:textSize="14dp"
        android:textColor="#222222"/>


</RelativeLayout>

好的全部完成，应该是自我解释

完整的应用结构

<强>结果

Answer 2

您永远不会设置活动视图。

setContentView(R.layout.yourlayout);

将记分板添加到android studio应用程序

2 个答案: