[英]Can't catch Java (Android) Exception with try-catch
I'm a Java (Android) beginner (coming from Python) and I'm trying to catch an exception using Try-Catch as follows: 我是Java(Android)初学者(来自Python),并且尝试使用Try-Catch捕获异常,如下所示:
try {
u.save();
} catch (Exception e) {
Log.wtf("DO THIS", " WHEN SAVE() FAILS");
}
To my surprise I don't see my Log message but I still get the following error: 令我惊讶的是,我没有看到日志消息,但仍然收到以下错误:
09-25 10:53:32.147: E/SQLiteDatabase(7991): android.database.sqlite.SQLiteConstraintException: error code 19: constraint failed
09-25 10:53:32.147:E / SQLiteDatabase(7991):android.database.sqlite.SQLiteConstraintException:错误代码19:约束失败
Why doesn't it catch the Exception? 为什么它没有捕获到异常? Am I doing something wrong here?
我在这里做错什么了吗? All tips are welcome!
欢迎所有提示!
The save() method looks as follows: save()方法如下所示:
public final void save() {
final SQLiteDatabase db = Cache.openDatabase();
final ContentValues values = new ContentValues();
for (Field field : mTableInfo.getFields()) {
final String fieldName = mTableInfo.getColumnName(field);
Class<?> fieldType = field.getType();
field.setAccessible(true);
try {
Object value = field.get(this);
if (value != null) {
final TypeSerializer typeSerializer = Cache.getParserForType(fieldType);
if (typeSerializer != null) {
// serialize data
value = typeSerializer.serialize(value);
// set new object type
if (value != null) {
fieldType = value.getClass();
// check that the serializer returned what it promised
if (!fieldType.equals(typeSerializer.getSerializedType())) {
Log.w(String.format("TypeSerializer returned wrong type: expected a %s but got a %s",
typeSerializer.getSerializedType(), fieldType));
}
}
}
}
// TODO: Find a smarter way to do this? This if block is necessary because we
// can't know the type until runtime.
if (value == null) {
values.putNull(fieldName);
}
else if (fieldType.equals(Byte.class) || fieldType.equals(byte.class)) {
values.put(fieldName, (Byte) value);
}
else if (fieldType.equals(Short.class) || fieldType.equals(short.class)) {
values.put(fieldName, (Short) value);
}
else if (fieldType.equals(Integer.class) || fieldType.equals(int.class)) {
values.put(fieldName, (Integer) value);
}
else if (fieldType.equals(Long.class) || fieldType.equals(long.class)) {
values.put(fieldName, (Long) value);
}
else if (fieldType.equals(Float.class) || fieldType.equals(float.class)) {
values.put(fieldName, (Float) value);
}
else if (fieldType.equals(Double.class) || fieldType.equals(double.class)) {
values.put(fieldName, (Double) value);
}
else if (fieldType.equals(Boolean.class) || fieldType.equals(boolean.class)) {
values.put(fieldName, (Boolean) value);
}
else if (fieldType.equals(Character.class) || fieldType.equals(char.class)) {
values.put(fieldName, value.toString());
}
else if (fieldType.equals(String.class)) {
values.put(fieldName, value.toString());
}
else if (fieldType.equals(Byte[].class) || fieldType.equals(byte[].class)) {
values.put(fieldName, (byte[]) value);
}
else if (ReflectionUtils.isModel(fieldType)) {
values.put(fieldName, ((Model) value).getId());
}
else if (ReflectionUtils.isSubclassOf(fieldType, Enum.class)) {
values.put(fieldName, ((Enum<?>) value).name());
}
}
catch (IllegalArgumentException e) {
Log.e(e.getClass().getName(), e);
}
catch (IllegalAccessException e) {
Log.e(e.getClass().getName(), e);
}
}
if (mId == null) {
mId = db.insert(mTableInfo.getTableName(), null, values);
}
else {
db.update(mTableInfo.getTableName(), values, "Id=" + mId, null);
}
Cache.getContext().getContentResolver()
.notifyChange(ContentProvider.createUri(mTableInfo.getType(), mId), null);
}
There are two classes to catch the problems. 有两个类可以解决问题。
Both are sub-class of Throwable class. 两者都是Throwable类的子类。 When there is situation we do not know, that particular code block will throw Exception or Error?
当有我们不知道的情况时,该特定代码块将抛出Exception或Error? You can use Throwable .
您可以使用Throwable 。 Throwable will catch both Errors & Exceptions .
Throwable将同时捕获Errors和Exceptions 。
Do this way 这样做
try {
u.save();
} catch (Throwable e) {
e.printStackTrace();
}
约束失败通常表示您做了类似将null
值传递到创建表时声明为非null
的列之类的操作。
do this way 这样做
try {
// do some thing which you want in try block
} catch (JSONException e) {
e.printStackTrace();
Log.e("Catch block", Log.getStackTraceString(e));
}
Try 尝试
try {
u.save();
} catch (SQLException sqle) {
Log.wtf("DO THIS", " WHEN SAVE() FAILS");
}catch (Exception e) {
Log.wtf("DO THIS", " WHEN SAVE() FAILS");
}
Log is expecting certain variable-names like verbose(v), debug(d) or info(i). Log期望使用某些变量名,例如verbose(v),debug(d)或info(i)。 Your "wtf" doesnt belong there.
您的“ wtf”不属于那里。 Check this answer for more info -->
检查此答案以获取更多信息->
https://stackoverflow.com/a/10006054/2074990 https://stackoverflow.com/a/10006054/2074990
or this: 或这个:
http://developer.android.com/tools/debugging/debugging-log.html http://developer.android.com/tools/debugging/debugging-log.html
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