Question

我有一个列表视图，显示整个星期的天气预报。我还在这个ListView上设置了一个适配器mForecastAdapter。但是当我预览fragment_main.xml文件时，我得到的预览就是这个

Fragment

这是我在MainActivity.java中的代码

package com.example.android.sunshine.app;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.app.ActionBarActivity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ListView;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;


public class MainActivity extends ActionBarActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    if (savedInstanceState == null) {
        getSupportFragmentManager().beginTransaction()
                .add(R.id.container, new PlaceholderFragment())
                .commit();
    }
}


@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
}

/**
 * A placeholder fragment containing a simple view.
 */
public static class PlaceholderFragment extends Fragment {

    public PlaceholderFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_main, container, false);
        String[] forecastArray = {
                "Today - Sunny - 88/64",
                "Tomorrow - Rainy - 73/54",
                "Wednesday - Snow - 63/54",
                "Thursday - Rainy - 83/54",
                "Friday - Rainy - 73/58",
                "Saturday - Gloomy - 64/54",
                "Sunday - Rainy - 73/64"
        };
        ArrayAdapter<String> mForecastAdapter;
        List<String> weekForecast = new ArrayList<String>(Arrays.asList(forecastArray));
        mForecastAdapter = new ArrayAdapter<String>(getActivity(), R.layout.list_item_forecast, R.id.list_item_forecast_textview, weekForecast);
        ListView listView = (ListView) rootView.findViewById(R.id.listview_forecast);
        listView.setAdapter(mForecastAdapter);
        return rootView;
    }
}

} ArrayAdapter有什么问题？如果这有任何不同，我正在使用Android Studio。

Answer 1

在布局预览中，默认情况下，ListView将显示与上面类似的列表，方法是显示默认的ListView，其中包含＆＃34;项目1＆＃34;，＆＃34;项目2＆＃34;，＆＃34;项目3＆＃34;等...和＆＃34;子项目1＆＃34;，＆＃34;子项目2＆＃34;，＆＃34;子项目3＆＃ 34;等...

在您在模拟器中运行应用程序或在实际设备上进行测试之前，您将无法看到实际的ListView（假设您已正确编码）。

ArrayAdapter无法按预期工作

1 个答案: