Question

我做得对吗？当我按下时，我希望使用SharedPreferences保存卡片阵列（对象），但每当我运行程序时，都会出现错误。或者我应该在onCreate上转换对象吗？

@Override
    protected void onPause() {

        String json = new Gson().toJson(cards);
        SharedPreferences prefs = getSharedPreferences("CARDARRAY",
                MODE_PRIVATE);
        SharedPreferences.Editor editor = prefs.edit();
        editor.putString("carddArray", json);
        editor.commit();
        Toast.makeText(getBaseContext(), "Settings saved", Toast.LENGTH_SHORT)
                .show();

        super.onPause();
    }

logcat的

02-13 23:22:50.091: E/AndroidRuntime(17941): FATAL EXCEPTION: main
02-13 23:22:50.091: E/AndroidRuntime(17941): java.lang.NoClassDefFoundError: com.google.gson.Gson
02-13 23:22:50.091: E/AndroidRuntime(17941):    at edu.np.ece.mapg.flashnote.Collections.onPause(Collections.java:118)
02-13 23:22:50.091: E/AndroidRuntime(17941):    at android.app.Activity.performPause(Activity.java:5319)
02-13 23:22:50.091: E/AndroidRuntime(17941):    at android.app.Instrumentation.callActivityOnPause(Instrumentation.java:1226)
02-13 23:22:50.091: E/AndroidRuntime(17941):    at android.app.ActivityThread.performPauseActivity(ActivityThread.java:3142)
02-13 23:22:50.091: E/AndroidRuntime(17941):    at android.app.ActivityThread.performPauseActivity(ActivityThread.java:3111)
02-13 23:22:50.091: E/AndroidRuntime(17941):    at android.app.ActivityThread.handlePauseActivity(ActivityThread.java:3089)
02-13 23:22:50.091: E/AndroidRuntime(17941):    at android.app.ActivityThread.access$800(ActivityThread.java:154)
02-13 23:22:50.091: E/AndroidRuntime(17941):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1265)
02-13 23:22:50.091: E/AndroidRuntime(17941):    at android.os.Handler.dispatchMessage(Handler.java:99)
02-13 23:22:50.091: E/AndroidRuntime(17941):    at android.os.Looper.loop(Looper.java:137)
02-13 23:22:50.091: E/AndroidRuntime(17941):    at android.app.ActivityThread.main(ActivityThread.java:5214)
02-13 23:22:50.091: E/AndroidRuntime(17941):    at java.lang.reflect.Method.invokeNative(Native Method)
02-13 23:22:50.091: E/AndroidRuntime(17941):    at java.lang.reflect.Method.invoke(Method.java:511)
02-13 23:22:50.091: E/AndroidRuntime(17941):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:795)
02-13 23:22:50.091: E/AndroidRuntime(17941):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:562)
02-13 23:22:50.091: E/AndroidRuntime(17941):    at dalvik.system.NativeStart.main(Native Method)

Answer 1

您似乎没有在gradle文件中添加GSON库：

dependencies {  compile 'com.google.code.gson:gson:2.2.+' }

将对象转换为json并使用sharedpreferences进行保存

1 个答案: