move ObservableXXXX classes under utils/

[mobile-ledger.git] / app / src / main / java / net / ktnx / mobileledger / utils / ObservableValue.java

diff --git a/app/src/main/java/net/ktnx/mobileledger/utils/ObservableValue.java b/app/src/main/java/net/ktnx/mobileledger/utils/ObservableValue.java
new file mode 100644 (file)
index 0000000..01fa092
--- /dev/null
+++ b/app/src/main/java/net/ktnx/mobileledger/utils/ObservableValue.java
@@ -0,0 +1,75 @@
+/*
+ * Copyright © 2019 Damyan Ivanov.
+ * This file is part of Mobile-Ledger.
+ * Mobile-Ledger is free software: you can distribute it and/or modify it
+ * under the term of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your opinion), any later version.
+ *
+ * Mobile-Ledger is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License terms for details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Mobile-Ledger. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package net.ktnx.mobileledger.utils;
+
+import java.util.Observable;
+import java.util.Observer;
+
+public class ObservableValue<T> {
+    private final ObservableValueImpl<T> impl = new ObservableValueImpl<>();
+    public ObservableValue() {}
+    public ObservableValue(T initialValue) {
+        impl.setValue(initialValue, false);
+    }
+    public void set(T newValue) {
+        impl.setValue(newValue);
+    }
+    public T get() {
+        return impl.getValue();
+    }
+    public void addObserver(Observer o) {
+        impl.addObserver(o);
+    }
+    public void deleteObserver(Observer o) {
+        impl.deleteObserver(o);
+    }
+    public void notifyObservers() {
+        impl.notifyObservers();
+    }
+    public void notifyObservers(Object arg) {
+        impl.notifyObservers(arg);
+    }
+    public void deleteObservers() {
+        impl.deleteObservers();
+    }
+    public boolean hasChanged() {
+        return impl.hasChanged();
+    }
+    public int countObservers() {
+        return impl.countObservers();
+    }
+    private class ObservableValueImpl<T> extends Observable {
+        protected T value;
+        public void setValue(T newValue) {
+            setValue(newValue, true);
+        }
+        private synchronized void setValue(T newValue, boolean notify) {
+            if ((newValue == null) && (value == null)) return;
+
+            if ((newValue != null) && newValue.equals(value)) return;
+
+            T oldValue = value;
+            value = newValue;
+            setChanged();
+            if (notify) notifyObservers(oldValue);
+        }
+        public T getValue() {
+            return value;
+        }
+    }
+}
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