小编hes*_*ham的帖子

我想使用Gson库将学生列表作为列表从AsyncTask传递给Activity

但它给了我以下错误:

错误日志:

       FATAL EXCEPTION: main
   java.lang.RuntimeException: Unable to start activity ComponentInfo{com.hesham.sams/com.hesham.sams.ListActivity1}: com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was BEGIN_ARRAY at line 1 column 2
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2110)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2135)
    at android.app.ActivityThread.access$700(ActivityThread.java:140)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1237)
    at android.os.Handler.dispatchMessage(Handler.java:99)
    at android.os.Looper.loop(Looper.java:137)
    at android.app.ActivityThread.main(ActivityThread.java:4921)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:511)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1038)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:805)
    at dalvik.system.NativeStart.main(Native Method)
   Caused by: com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was BEGIN_ARRAY at line 1 column 2
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:176)
    at com.google.gson.Gson.fromJson(Gson.java:803)
    at com.google.gson.Gson.fromJson(Gson.java:768)
    at com.google.gson.Gson.fromJson(Gson.java:717)
    at com.google.gson.Gson.fromJson(Gson.java:689)
    at com.hesham.sams.ListActivity1.getNames(ListActivity1.java:171)
    at com.hesham.sams.ListActivity1.onCreate(ListActivity1.java:68)
    at android.app.Activity.performCreate(Activity.java:5206) …

我有jsf网页,这需要从以前的页面查询一些字符串.

我的问题是这个主页似乎有缓存的值,没有变化即使我将这些值更改为null,它应该得到空页但它变得更旧的值.

所以我的问题是:每当我调用它或按F按钮时,如何让我的主jsf页面重新加载或缓存被删除？

我试过的JSF示例代码:

     <h:head style="width: 200px; ">
    <f:facet name="first">
        <meta http-equiv="X-UA-Compatible" content="edge, chrome=1" />
        <meta http-equiv="Cache-Control" content="no-cache, no-store, must-revalidate" />
<meta http-equiv="Pragma" content="no-cache" />
<meta http-equiv="Expires" content="-1" />
    </f:facet>

java类:

String SID = FacesContext.getCurrentInstance().getExternalContext()
        .getRequestParameterMap().get("SID");

String from = FacesContext.getCurrentInstance().getExternalContext()
        .getRequestParameterMap().get("from");

String to = FacesContext.getCurrentInstance().getExternalContext()
        .getRequestParameterMap().get("to");

String class_id = FacesContext.getCurrentInstance()
        .getExternalContext().getRequestParameterMap().get("class_id");


if (SID==null) {
    try {
        Dbconnection NewConnect = new Dbconnection();
        Connection con = NewConnect.MakeConnect();
        Statement stmt = con.createStatement();
        ResultSet rs = stmt
                .executeQuery("SELECT a.course_id, a.teacher_id, a.class_id, a.day_id, a.state, a.apssent_date, …