Question

我还是Android新手，我主要是iOS开发人员。

我不知道为什么我无法测试ListArray是否为空。无论如何，我需要测试并使用它的大小。

这是在课堂上宣布的：
项目项目=新项目（）;

以下代码不喜欢将projects.videos.size（）与nil或0进行比较。

try
{

if (projects != null)
{
int numberOfVideos = projects.videos.size();
    if(numberOfVideos==0)
    {
//           myStringArray = new String[projects.videos.size()];
//          
//          
//          
//          for (int i = 0;i < projects.videos.size();i++)
//          {
//              myStringArray[i] = projects.videos.get(i);
//          }
    }   
    else
    {
//          myStringArray = new String[1];
//          myStringArray[0] = "No projects";
    }
}
else
{
    System.out.println("Sucess");
}

}

catch (Exception e)
{
System.out.println(e);
System.out.println("somethingbad has happened");
System.out.println(projects.videos.size());
}

这就是项目类的样子：

 package com.example.musicvideomaker;

import java.util.ArrayList;
import java.util.UUID;
import java.io.Serializable;

@SuppressWarnings("serial")
public class Projects implements Serializable{

public String projectName;
public String musicStuff;
public String songTitle;
public String guid;
public boolean isBuiltVideo;
public boolean isListOfBuiltVideos;
public int selectedIndex;

public ArrayList<String> videos;
public ArrayList<String> builtVideos;
public ArrayList<Number> tPoints;

public void setProjectName(String projectName)
{
    this.projectName = projectName;
}

public void setMusicStuff(String musicStuff)
{
    this.musicStuff = musicStuff;
}

public void setSongTitle(String songTitle)
{
    this.songTitle = songTitle;
}

public void setGuid()
{
    UUID uuid = UUID.randomUUID();
    this.guid = uuid.toString();
}

public void isBuiltVideo(boolean isBuiltVideo)
{
    this.isBuiltVideo = isBuiltVideo;
}

public void isListOfBuiltVideos(boolean isListOfBuiltVideos)
{
    this.isListOfBuiltVideos = isListOfBuiltVideos;
}

public void setSelectedIndex(int selectedIndex)
{
    this.selectedIndex = selectedIndex;
}

public void addRecordedVideo(String recordedVideo)
{
    this.videos.add(recordedVideo);
}

public void addBuiltVideo(String builtVideo)
{
    this.builtVideos.add(builtVideo);
}

public void addTPoint(Number tPoint)
{
    this.tPoints.add(tPoint);
}


}

Answer 1

我删除了int numberOfVideos = projects.videos.size（）;

我没有使用if（numberOfVideos == 0）而是使用了projects.videos == null

我认为这是因为我的项目为null因此在尝试拉出arrayList的大小时会崩溃。

从另一个序列化类加载ArrayList以在ListView中使用

1 个答案: