Question

尝试实现高分ListView。我想在我的ListView中添加一个适配器。我用3个TextView元素构建了自己的Adapter。我的ListView甚至没有显示在我的活动中。

private class HighscoreAdapter extends ArrayAdapter<String> {

    private class ViewHolder {
        private TextView name;
        private TextView highscore;
        private TextView date;
    }

    private final Context context;
    private final String[] values;
    private final int textViewResourceId;

    public HighscoreAdapter(Context context, int textViewResourceId, String[] values) {
        super(context, textViewResourceId);
        this.textViewResourceId = textViewResourceId;
        this.context = context;
        this.values = values;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {

        final ViewHolder viewHolder;

        if (convertView == null) {
            convertView = getLayoutInflater().inflate(textViewResourceId, parent, false);
            viewHolder = new ViewHolder();
            viewHolder.name = (TextView) convertView.findViewById(R.id.highscore_name);
            viewHolder.highscore = (TextView) convertView.findViewById(R.id.highscore_points);
            viewHolder.date = (TextView) convertView.findViewById(R.id.highscore_date);
        } else {
            viewHolder = (ViewHolder) convertView.getTag();
        }

        viewHolder.name.setText("xman");
        viewHolder.highscore.setText("2000");
        viewHolder.date.setText("today");

        return convertView;
    }
}

这是我在与HighscoreAdapter相同的类中的onCreate方法。 R.layout.list_line包含所有三个TextView元素：

public class HighScore extends Activity {

    ...

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

    final ListView listview = (ListView) findViewById(android.R.id.list);

    String[] values = new String[] { "one", "two", "three"};

    final HighscoreAdapter highscoreAdapter = new HighscoreAdapter(this, R.layout.list_line, values);
    listview.setAdapter(highscoreAdapter);

}

...

private class HighscoreAdapter extends ...

}

这是我的活动布局：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="?android:attr/listPreferredItemHeight"
    android:padding="6dip" >
....

<ListView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginTop="70dp"
    android:layout_marginBottom="70dp"
    android:id="@+id/highscore_listview"
    android:layout_gravity="center_horizontal" />
</RelativeLayout>

这是我的list_line.xml布局：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="?android:attr/listPreferredItemHeight"
    android:padding="6dip" >

    <TextView
        android:id="@+id/icon"
        android:layout_width="30dip"
        android:layout_height="26dip"
        android:layout_alignParentBottom="true"
        android:layout_alignParentTop="true"
        android:layout_marginRight="6dip"
        android:contentDescription="TODO"
        android:textSize="40sp"
        android:text="1"/>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:layout_toRightOf="@+id/icon"
        android:text="Large Text"
        android:id="@+id/highscore_name"
        android:layout_centerVertical="true"
        android:layout_toEndOf="@+id/icon" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="20.000"
        android:id="@+id/highscore_points"
        android:layout_alignParentTop="true"
        android:layout_alignParentEnd="true"
        android:textSize="23dp"/>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="30 Dec 2015"
        android:id="@+id/highscore_date"
        android:layout_below="@id/highscore_points"
        android:layout_alignParentEnd="true"
        android:textSize="15dp" />

</RelativeLayout>

Answer 1

更改您的适配器，如下所示：

import android.app.Activity;
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 java.util.ArrayList;

public class HighScoreAdapter extends BaseAdapter {
private ArrayList<String> items;
private Context context;

public HighScoreAdapter(Context context, ArrayList<String> items){
    this.context = context;
    this.items = items;
}

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

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

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

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    if(convertView == null){
        LayoutInflater layoutInflater = (LayoutInflater)
                context.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
        convertView = layoutInflater.inflate(R.layout.list_line, null);
    }
    TextView name, highscore, date;
    name = (TextView) convertView.findViewById(R.id.highscore_name);
    highscore = (TextView) convertView.findViewById(R.id.highscore_points);
    date = (TextView) convertView.findViewById(R.id.highscore_date);

    name.setText(items.get(position));
    highscore.setText(items.get(position));
    date.setText(items.get(position));
    return convertView;
}

}

而不是像下面那样使用它：

String[] values = new String[] { "one", "two", "three"};

    ArrayList<String> items = new ArrayList<>();
    for (String item : values){
        items.add(item);
    }

    final HighScoreAdapter highscoreAdapter = new HighScoreAdapter(this, items);
    listview.setAdapter(highscoreAdapter);

Answer 2

首先改变这一行：

ListView listview = (ListView) findViewById(android.R.id.list);

为：

ListView listview = (ListView) findViewById(R.id.highscore_listview);

**你应该使用你的包R类来查找id，你应该设置正确的id：D

一些提示：

为什么你为两个TextView使用相同的id？为每个视图使用uniqe id！我觉得final关键字在这里没用！为什么你使用final作为listview？

Answer 3

这是问题

final ListView listview = (ListView) findViewById(android.R.id.list);

您在此处使用了错误的ListView ID（android.R.id.list）。

将其更改为R.id.my_list，格式为R.layout.highscore_activity

<强>更新

更改

final ListView listview = (ListView) findViewById(android.R.id.list);

到

final ListView listview = (ListView) findViewById(R.id.highscore_listview);

Answer 4

此

final ListView listview = (ListView) findViewById(android.R.id.list);

应该是

final ListView listview = (ListView) findViewById(android.R.id.highscore_listview);

Answer 5

您的ListView应如下所示：

<ListView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginTop="70dp"
    android:layout_marginBottom="70dp"
    android:id="@android:id/list"
    android:layout_gravity="center_horizontal" />

Android - ListView适配器不可见

5 个答案: