我使用 Realm 开发我的登录应用程序。 我在“Config myConfig = mRealm.createObject(Config.class)”行中将我的 token 写在 Realm 中。之后从 Realm 读取没有结果，同样 Realm 没有条目。 我确实 checkin 了我标记为“//check - 为什么这里没有用户”的这段代码。 并且 User.size() 等于零。
public class MainActivity extends AppCompatActivity {
private Realm mRealm;
private Realm mRealmInstance;
Button btnLogin;
public void onLogin() {
AsyncHttpClient client = new AsyncHttpClient();
RequestParams rp = new RequestParams();
rp.add("email", "name@example.com");
rp.add("password", "159753");
RequestHandle post = client.post("https://example.com/api/v1/auth", rp, new JsonHttpResponseHandler() {
@Override
public void onSuccess(int statusCode, Header[] headers, JSONObject response) {
// Root JSON in response is an dictionary i.e { "data : [ ... ] }
// Handle resulting parsed JSON response here
try {
String tokenString = response.getString("token");
mRealm.beginTransaction();
Config myConfig = mRealm.createObject(Config.class);
myConfig.name = "token";
myConfig.tokenValue = tokenString;
mRealm.commitTransaction();
} catch (NullPointerException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
}
}
@Override
public void onFailure(int statusCode, Header[] headers, String res, Throwable t) {
// called when response HTTP status is "4XX" (eg. 401, 403, 404)
}
});
//check - why no users here
TextView tvHello = (TextView)findViewById(R.id.tvHello);
try {
RealmResults User = mRealmInstance.where(Config.class).equalTo("name", "token").findAllAsync();
if (User.size() > 0) {
String nameOfUser = User.get(0).toString();
tvHello.setText(nameOfUser);
} else if (User.size() == 0) {
Log.e("query","query size is "+User.size());
}
} catch (Exception e) {
e.printStackTrace();
}
//end of test block
}
最佳答案
在访问您的数据之前，您正在进行异步网络调用。网络调用尚未完成，因此您的数据为空。将您的数据访问代码放在 onSuccess() 回调中。
public class MainActivity extends AppCompatActivity {
...
public void onLogin() {
...
RequestHandle post = client.post(
"https://example.com/api/v1/auth",
rp,
new JsonHttpResponseHandler() {
@Override
public void onSuccess(
int statusCode,
Header[] headers,
JSONObject response) {
try {
String tokenString = response.getString("token");
mRealm.beginTransaction();
Config myConfig = mRealm.createObject(Config.class);
myConfig.name = "token";
myConfig.tokenValue = tokenString;
mRealm.commitTransaction();
populateData();
} catch (NullPointerException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
}
}
@Override
public void onFailure(
int statusCode,
Header[] headers,
String res,
Throwable t) {
// called when response HTTP status is "4XX" (eg. 401, 403, 404)
}
});
}
private void populateData() {
TextView tvHello = (TextView)findViewById(R.id.tvHello);
try {
RealmResults User =
mRealmInstance.where(Config.class).equalTo("name", "token").findAll();
if (User.size() > 0) {
String nameOfUser = User.get(0).toString();
tvHello.setText(nameOfUser);
} else if (User.size() == 0) {
Log.e("query","query size is "+User.size());
}
} catch (Exception e) {
e.printStackTrace();
}
}
另请注意，您应该使用 findAll() 而不是 findAllAsync()。阅读文档以获取有关差异的更多信息:https://realm.io/blog/realm-java-0-84-0/
关于android - 如何从 Realm 中读取数据，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/48201986/