-2

可能重复：
单击检查数据按钮
时出现空指针异常 当我单击按钮时引发空指针异常

我无法在我的代码中处理空指针异常

在这一行中出现错误DataManipulator.createCertificatesEntry((Certificates) testCertificates); 这是我的 createCertificatesEntry

 public void createCertificatesEntry(Certificates certificates) {
            ByteArrayOutputStream out = new ByteArrayOutputStream();
            certificates.getBitmap().compress(Bitmap.CompressFormat.PNG, 100, out);
            ContentValues cv = new ContentValues();
            cv.put(KEY_IMG, out.toByteArray());
            mDb.insert(CERTIFICATES_TABLE,  null, cv);
        }

这段代码有什么问题吗

this is logcat
05-29 12:57:42.577: E/AndroidRuntime(625): FATAL EXCEPTION: main
05-29 12:57:42.577: E/AndroidRuntime(625): java.lang.RuntimeException: Unable to start activity ComponentInfo{list.certificates/list.certificates.CheckData}: java.lang.NullPointerException
05-29 12:57:42.577: E/AndroidRuntime(625):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1955)
05-29 12:57:42.577: E/AndroidRuntime(625):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1980)
05-29 12:57:42.577: E/AndroidRuntime(625):  at android.app.ActivityThread.access$600(ActivityThread.java:122)
05-29 12:57:42.577: E/AndroidRuntime(625):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1146)
05-29 12:57:42.577: E/AndroidRuntime(625):  at android.os.Handler.dispatchMessage(Handler.java:99)
05-29 12:57:42.577: E/AndroidRuntime(625):  at android.os.Looper.loop(Looper.java:137)
05-29 12:57:42.577: E/AndroidRuntime(625):  at android.app.ActivityThread.main(ActivityThread.java:4340)
05-29 12:57:42.577: E/AndroidRuntime(625):  at java.lang.reflect.Method.invokeNative(Native Method)
05-29 12:57:42.577: E/AndroidRuntime(625):  at java.lang.reflect.Method.invoke(Method.java:511)
05-29 12:57:42.577: E/AndroidRuntime(625):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
05-29 12:57:42.577: E/AndroidRuntime(625):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
05-29 12:57:42.577: E/AndroidRuntime(625):  at dalvik.system.NativeStart.main(Native Method)
05-29 12:57:42.577: E/AndroidRuntime(625): Caused by: java.lang.NullPointerException
05-29 12:57:42.577: E/AndroidRuntime(625):  at list.certificates.DataManipulator.createCertificatesEntry(DataManipulator.java:61)
05-29 12:57:42.577: E/AndroidRuntime(625):  at list.certificates.CheckData.onCreate(CheckData.java:28)
05-29 12:57:42.577: E/AndroidRuntime(625):  at android.app.Activity.performCreate(Activity.java:4465)
05-29 12:57:42.577: E/AndroidRuntime(625):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
05-29 12:57:42.577: E/AndroidRuntime(625):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1919)
05-29 12:57:42.577: E/AndroidRuntime(625):  ... 11 more
4

2 回答 2

0

您的 this 链中的一个对象为 nulllist.certificates.DataManipulator

于 2012-05-29T09:49:38.307 回答
0

当您在 DataManipulator.createCertificatesEntry( (Certificates) testCertificates) 行传递 Activity 中为空的“对象 testCertificates”时；

在 DataManipulator.createCertificatesEntry 方法中，证书为空，因此 certificate.getBitmap() 将在这里通过空指针 excption

 public void createCertificatesEntry(Certificates certificates) 
    { 
     ByteArrayOutputStream out = new ByteArrayOutputStream();
     certificates.getBitmap().compress(Bitmap.CompressFormat.PNG, 100, out);
     ContentValues cv = new ContentValues();
     cv.put(KEY_IMG, out.toByteArray());
     mDb.insert(CERTIFICATES_TABLE, null, cv);
     }

使用此行在 Activity 中的 DataManipulator.createCertificatesEntry 中传递非空值

证书 testCertificates = new Certificates(BitmapFactory.decodeFile(Context.STORAGE_SERVICE));

以上

DataManipulator.createCertificatesEntry((Certificates) testCertificates);

于 2012-05-29T09:02:41.487 回答