Java 返回包含rest api项的列表时出现问题
我对Android中的一个方法有一个问题,它应该返回从RESTAPI接收的项目列表。我能够在该方法中调试这些项,因为我在onCreate方法中编写了该方法的声明。但是,当我尝试将这些项(在该方法中)添加到列表中时,问题就出现了,因此该方法可以返回这些项。我收到如下错误:Java 返回包含rest api项的列表时出现问题,java,android,Java,Android,我对Android中的一个方法有一个问题,它应该返回从RESTAPI接收的项目列表。我能够在该方法中调试这些项,因为我在onCreate方法中编写了该方法的声明。但是,当我尝试将这些项(在该方法中)添加到列表中时,问题就出现了,因此该方法可以返回这些项。我收到如下错误: Caused by: java.lang.IndexOutOfBoundsException: Index: 0, Size: 0 应返回项目的方法: public List<Categories> display
Caused by: java.lang.IndexOutOfBoundsException: Index: 0, Size: 0
应返回项目的方法:
public List<Categories> displayDataaaa(List<Categories> categoriesList) {
this.categoriesList = new ArrayList<Categories>();
/
String cat_name = "";
// this.categoriesList.add(new Categories(1,"lkajsdflk"));
this.categoriesList.add(new Categories(1, categoriesList.get(0).getCategoriesName()));
for (int i = 0; i < categoriesList.size(); i++) {
cat_name = categoriesList.get(i).getCategoriesName();
// this.categoriesList.add(new Categories(i, cat_name));
Log.d("displayDataaaaa-cat_name", "displayDataaaaa-cat_name" + cat_name);
this.categoriesList.addAll(categoriesList);
}
// this.categoriesList.add(new Categories(1, cat_name));
return this.categoriesList;
}
这是你的问题线
categoriesList.get(0)
在categoriesList
为空时将引发异常。在哪一行发生异常?当我尝试向列表中添加项目时,请提供日志,因此:this.categoriesList.add(新类别(1,categoriesList.get(0).getCategoriesName())@Shivendra Tiwari我添加了日志,因为您的日志表明列表的大小为0,并且您正在尝试从列表中检索数据。调试并检查方法的参数问题是categoriesList不是空的,我可以调试方法内部的项(在onCreate方法中声明方法的名称-我可以看到方法中发生了什么,我调试从api收到的列表项),但无法将任何项添加到列表中,因此我可以返回该方法。
java.lang.RuntimeException: Unable to start activity ComponentInfo{dev4passion.partyj10/dev4passion.partyj10.MainActivity}: java.lang.IndexOutOfBoundsException: Index: 0, Size: 0
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2913)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3048)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1808)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:6669)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
Caused by: java.lang.IndexOutOfBoundsException: Index: 0, Size: 0
at java.util.ArrayList.get(ArrayList.java:437)
at dev4passion.partyj10.MainActivity.displayDataaaa(MainActivity.java:189)
at dev4passion.partyj10.MainActivity.onCreate(MainActivity.java:94)
at android.app.Activity.performCreate(Activity.java:7136)
at android.app.Activity.performCreate(Activity.java:7127)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1271)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2893)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3048)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1808)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:6669)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
this.categoriesList.add(new Categories(1, categoriesList.get(0).getCategoriesName()));