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BAEL-2800_Copying_a_HashMap_in_Java - methods added

This commit is contained in:
Anshul Bansal 2019-04-03 17:14:31 +03:00
parent 4878cc2716
commit cdb37dddda
2 changed files with 36 additions and 27 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

25
core-java-collections-2/src/main/java/com/baeldung/copyinghashmap/CopyHashMap.java
View File

@ -8,8 +8,17 @@ import java.util.stream.Collectors;
import org.apache.commons.lang3.SerializationUtils;
public class CopyHashMap {
public static HashMap copyUsingConstructor(HashMap originalMap) {
return new HashMap(originalMap);
}
public static HashMap copyUsingClone(HashMap originalMap) {
return (HashMap) originalMap.clone();
}
public static HashMap basicCopy(HashMap originalMap, HashMap copyMap) {
public static HashMap copyUsingPut(HashMap originalMap) {
HashMap copyMap = new HashMap();
Set<Map.Entry> entries = originalMap.entrySet();
for(Map.Entry mapEntry: entries) {
copyMap.put(mapEntry.getKey(), mapEntry.getValue());
@ -18,8 +27,8 @@ public class CopyHashMap {
return copyMap;
}
public static Map copyUsingPutAll(Map originalMap, Map copyMap) {
public static Map copyUsingPutAll(Map originalMap) {
HashMap copyMap = new HashMap();
copyMap.putAll(originalMap);
return copyMap;
@ -34,8 +43,16 @@ public class CopyHashMap {
return copyMap;
}
public static HashMap copyMapAndConvertCmsToInches(HashMap originalMap) {
Set<Map.Entry> entries = originalMap.entrySet();
HashMap copyMap = (HashMap) entries
.stream()
.collect(Collectors.toMap(mapEntry -> mapEntry.getKey(), mapEntry -> (int)mapEntry.getValue()/2.54));
return copyMap;
}
public static HashMap shallowCopy(HashMap originalMap) {
//return new HashMap(originalMap);
return (HashMap) originalMap.clone();
}

38
core-java-collections-2/src/test/java/com/baeldung/copyinghashmap/CopyHashMapUnitTest.java
View File

@ -12,27 +12,6 @@ import com.google.common.collect.ImmutableMap;
public class CopyHashMapUnitTest {
@Test
public void givenHashmap_whenCopy_thenCopyContainsAllMappings() {
HashMap<String, String> colorMap = new HashMap<>();
colorMap.put("1", "Red");
colorMap.put("2", "Blue");
colorMap.put("3", "Green");
System.out.println("ColorMap content : " + colorMap);
HashMap<String, String> colorMapCopy = new HashMap<>();
colorMapCopy.put("1", "Orange");
colorMapCopy.put("4", "Black");
colorMapCopy = CopyHashMap.basicCopy(colorMap, colorMapCopy);
System.out.println("ColorMapCopy content : " +colorMapCopy);
assertEquals(4, colorMapCopy.size());
}
@Test
public void givenHashMap_whenShallowCopy_thenCopyisNotSameAsOriginal() {
@ -80,7 +59,21 @@ public class CopyHashMapUnitTest {
assertThat(employeeMapDeepCopy.get("employee1"))
.isNotEqualTo(employeeMap.get("employee1"));
}
}
@Test
public void givenHashMapWithValuesInCms_whenCopy_thenCopyMapShouldHaveValuesInInches() {
HashMap<String, Integer> heightMap = new HashMap<>();
heightMap.put("emp1", 160);
heightMap.put("emp2", 165);
heightMap.put("emp3", 163);
HashMap heightMapInInches = CopyHashMap.copyMapAndConvertCmsToInches(heightMap);
assertThat(heightMap).isNotEqualTo(heightMapInInches);
assertThat(heightMap.get("emp1")/2.54).isEqualTo(heightMapInInches.get("emp1"));
}
@Test
public void givenImmutableMap_whenCopyUsingGuava_thenCopyShouldNotChange() {
@ -95,6 +88,5 @@ public class CopyHashMapUnitTest {
assertThat(heightMapCopy).isSameAs(heightMap);
}
}