IllegalStateException：找不到只有帮助类 null 的（上下文）参数的构造函数答案

【问题标题】：IllegalStateException: Could not find constructor that hast just a (Context) argument for helper class nullIllegalStateException：找不到只有帮助类 null 的（上下文）参数的构造函数
【发布时间】：2013-08-12 13:14:47
【问题描述】：

您好，我的 logcat 出现错误：

08-12 12:49:07.095: E/AndroidRuntime(4151): FATAL EXCEPTION: main
08-12 12:49:07.095: E/AndroidRuntime(4151): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.kns.expense.activty/com.kns.expense.activty.AddExpenseActivity}: java.lang.IllegalStateException: Could not find constructor that hast just a (Context) argument for helper class null
08-12 12:49:07.095: E/AndroidRuntime(4151):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
08-12 12:49:07.095: E/AndroidRuntime(4151):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
08-12 12:49:07.095: E/AndroidRuntime(4151):     at android.app.ActivityThread.access$600(ActivityThread.java:141)
08-12 12:49:07.095: E/AndroidRuntime(4151):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
08-12 12:49:07.095: E/AndroidRuntime(4151):     at android.os.Handler.dispatchMessage(Handler.java:99)
08-12 12:49:07.095: E/AndroidRuntime(4151):     at android.os.Looper.loop(Looper.java:137)
08-12 12:49:07.095: E/AndroidRuntime(4151):     at android.app.ActivityThread.main(ActivityThread.java:5041)
08-12 12:49:07.095: E/AndroidRuntime(4151):     at java.lang.reflect.Method.invokeNative(Native Method)
08-12 12:49:07.095: E/AndroidRuntime(4151):     at java.lang.reflect.Method.invoke(Method.java:511)
08-12 12:49:07.095: E/AndroidRuntime(4151):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
08-12 12:49:07.095: E/AndroidRuntime(4151):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
08-12 12:49:07.095: E/AndroidRuntime(4151):     at dalvik.system.NativeStart.main(Native Method)
08-12 12:49:07.095: E/AndroidRuntime(4151): Caused by: java.lang.IllegalStateException: Could not find constructor that hast just a (Context) argument for helper class null
08-12 12:49:07.095: E/AndroidRuntime(4151):     at com.j256.ormlite.android.apptools.OpenHelperManager.constructHelper(OpenHelperManager.java:210)
08-12 12:49:07.095: E/AndroidRuntime(4151):     at com.j256.ormlite.android.apptools.OpenHelperManager.loadHelper(OpenHelperManager.java:165)
08-12 12:49:07.095: E/AndroidRuntime(4151):     at com.j256.ormlite.android.apptools.OpenHelperManager.getHelper(OpenHelperManager.java:75)
08-12 12:49:07.095: E/AndroidRuntime(4151):     at com.kns.expense.db.DatabaseManager.getHelper(DatabaseManager.java:18)
08-12 12:49:07.095: E/AndroidRuntime(4151):     at com.kns.expense.db.Repo.<init>(Repo.java:13)
08-12 12:49:07.095: E/AndroidRuntime(4151):     at com.kns.expense.activty.AddExpenseActivity.onCreate(AddExpenseActivity.java:48)
08-12 12:49:07.095: E/AndroidRuntime(4151):     at android.app.Activity.performCreate(Activity.java:5104)
08-12 12:49:07.095: E/AndroidRuntime(4151):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
08-12 12:49:07.095: E/AndroidRuntime(4151):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
08-12 12:49:07.095: E/AndroidRuntime(4151):     ... 11 more
08-12 12:49:07.095: E/AndroidRuntime(4151): Caused by: java.lang.NullPointerException
08-12 12:49:07.095: E/AndroidRuntime(4151):     at com.j256.ormlite.android.apptools.OpenHelperManager.constructHelper(OpenHelperManager.java:208)
08-12 12:49:07.095: E/AndroidRuntime(4151):     ... 19 more
08-12 12:49:10.305: D/dalvikvm(4175): GC_CONCURRENT freed 63K, 7% free 2776K/2984K, paused 74ms+3ms, total 207ms

在 Repo 代码中调用时：

public Repo(Context context) {  {
        DatabaseManager<DatabaseHelper> manager = new DatabaseManager<DatabaseHelper>();
        db = manager.getHelper(context, DatabaseHelper.class);// here getting error
        Users = new RepoUsers(db);
    }

DatabaseHelper 是

public class DatabaseHelper extends OrmLiteSqliteOpenHelper{

    private static final String DATABASE_NAME = "ezexpense.sqlite";
    private static final int DATABASE_VERSION = 1;

    private Dao<EzExpenseProject, String> userDao = null;
    private RuntimeExceptionDao<EzExpenseProject, String> userRuntimeDao = null;

    public DatabaseHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);

        DatabaseInitializer initializer = new DatabaseInitializer(context);
        try {
            initializer.createDatabase();
            initializer.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

请帮我解决这个错误？

【问题讨论】：

如果它是一个函数？返回类型在哪里？
也许你错过了给 super(...) 的电话？
我现在添加了 DatabaseHelper 类
我不明白你的意思
您使用的是什么版本的 ORMLite？您可以使用调试器并跟踪 ORMLite 代码并在该行放置一个断点并查看哪个变量为空？堆栈跟踪令人困惑。

标签： android sqlite ormlite

【解决方案1】：

有时会在您的应用程序的 gradle 文件中使用 Proguard 可以通过裁判use proguard for ormLite 修复

【讨论】：