Question

我知道我在这里写错了一些东西，我试图从JSON动态显示多行项目但是得到以下异常，

01-22 11:18:27.814: E/AndroidRuntime(438): FATAL EXCEPTION: main
01-22 11:18:27.814: E/AndroidRuntime(438): java.lang.NullPointerException
01-22 11:18:27.814: E/AndroidRuntime(438):  at com.nokia.item.MultiLineItem.createView(MultiLineItem.java:44)
01-22 11:18:27.814: E/AndroidRuntime(438):  at com.nokia.view.ViewFactory.getView(ViewFactory.java:122)
01-22 11:18:27.814: E/AndroidRuntime(438):  at com.nokia.view.DocumentList.createView(DocumentList.java:52)
01-22 11:18:27.814: E/AndroidRuntime(438):  at com.nokia.view.ViewFactory.getContainer(ViewFactory.java:85)
01-22 11:18:27.814: E/AndroidRuntime(438):  at com.nokia.controller.Controller.createDocument(Controller.java:415)
01-22 11:18:27.814: E/AndroidRuntime(438):  at com.nokia.model.SublistChooser.checkNextListTemplate(SublistChooser.java:99)
01-22 11:18:27.814: E/AndroidRuntime(438):  at com.nokia.model.SublistChooser.checkNextListTemplate(SublistChooser.java:96)
01-22 11:18:27.814: E/AndroidRuntime(438):  at com.nokia.model.SublistChooser.start(SublistChooser.java:50)
01-22 11:18:27.814: E/AndroidRuntime(438):  at com.nokia.controller.Controller.startDocument(Controller.java:387)
01-22 11:18:27.814: E/AndroidRuntime(438):  at com.nokia.controller.Controller.startDocument(Controller.java:379)
01-22 11:18:27.814: E/AndroidRuntime(438):  at com.nokia.action.ActionExecutor.executeTaskAction(ActionExecutor.java:445)
01-22 11:18:27.814: E/AndroidRuntime(438):  at com.nokia.action.ActionExecutor.onAction(ActionExecutor.java:288)
01-22 11:18:27.814: E/AndroidRuntime(438):  at com.nokia.action.Action.execute(Action.java:133)
01-22 11:18:27.814: E/AndroidRuntime(438):  at com.nokia.view.PopupList$1.onClick(PopupList.java:72)
01-22 11:18:27.814: E/AndroidRuntime(438):  at com.android.internal.app.AlertController$AlertParams$3.onItemClick(AlertController.java:920)
01-22 11:18:27.814: E/AndroidRuntime(438):  at android.widget.AdapterView.performItemClick(AdapterView.java:282)
01-22 11:18:27.814: E/AndroidRuntime(438):  at android.widget.AbsListView.performItemClick(AbsListView.java:1037)
01-22 11:18:27.814: E/AndroidRuntime(438):  at android.widget.AbsListView$PerformClick.run(AbsListView.java:2449)
01-22 11:18:27.814: E/AndroidRuntime(438):  at android.widget.AbsListView$1.run(AbsListView.java:3073)
01-22 11:18:27.814: E/AndroidRuntime(438):  at android.os.Handler.handleCallback(Handler.java:587)
01-22 11:18:27.814: E/AndroidRuntime(438):  at android.os.Handler.dispatchMessage(Handler.java:92)
01-22 11:18:27.814: E/AndroidRuntime(438):  at android.os.Looper.loop(Looper.java:132)
01-22 11:18:27.814: E/AndroidRuntime(438):  at android.app.ActivityThread.main(ActivityThread.java:4123)
01-22 11:18:27.814: E/AndroidRuntime(438):  at java.lang.reflect.Method.invokeNative(Native Method)
01-22 11:18:27.814: E/AndroidRuntime(438):  at java.lang.reflect.Method.invoke(Method.java:491)
01-22 11:18:27.814: E/AndroidRuntime(438):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
01-22 11:18:27.814: E/AndroidRuntime(438):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)
01-22 11:18:27.814: E/AndroidRuntime(438):  at dalvik.system.NativeStart.main(Native Method)
01-22 11:18:27.973: D/dalvikvm(438): GC_CONCURRENT freed 223K, 5% free 9758K/10247K, paused 9ms+27ms
01-22 11:18:34.123: I/Process(438): Sending signal. PID: 438 SIG: 9

这是我得到的代码NullPointerException，我不知道如何将视图设置为List。 View正在返回Null但正常TextFields的工作文件。请发布一些有用的代码。

import java.util.ArrayList;
import java.util.HashMap;

import org.json.JSONObject;

import android.view.View;
import android.widget.ListView;

import com.nokia.view.BaseScreen;
import com.nokia.view.BaseView;

public class MultiLineItem extends Item implements BaseView{

    private HashMap items;
    private  ArrayList list;
    public MultiLineItem(BaseScreen pview){
        super(pview);
        list= new ArrayList();
        items = new HashMap();
    }
    @Override
    public int getItemID() {
        // TODO Auto-generated method stub
        return 0;
    }
    @Override
    public String getValue() {
        // TODO Auto-generated method stub
        return null;
    }
    @Override
    public View getItem() {
        // TODO Auto-generated method stub
        return view;
    }
    public void createView(JSONObject definition) {
        String header=definition.optString("header");
        items.put("header", header);
        String text = definition.optString("text");
        items.put("text", text);
        list.add(items);
        //((ListView)view).addFocusables(list, LIST);
    }

    public ArrayList getList(){
        return list;
    }

Answer 1

Android中有一个Widget，你必须使用ListView。在ListView设置Adapter，在适配器中，您必须发送从Json获得的所有数据。这是执行Android ListView Tutorial的示例。本教程将为您提供有关如何在Application中使用ListView的建议。

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1 个答案: