iSharkFly-Docs
/
java-tutorials
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

[JAVA-6143] java copy from one hashmap to another (#13497) 

Co-authored-by: Bhaskar <bhaskar.dastidar@freshworks.com>
This commit is contained in:
Bhaskar Ghosh Dastidar 2023-02-18 22:27:14 +05:30 committed by GitHub
parent 749a077478
commit e11c4e3dbc
4 changed files with 136 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
core-java-modules/core-java-collections-maps-6/pom.xml Normal file
View File

@ -0,0 +1,20 @@
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<artifactId>core-java-collections-maps-6</artifactId>
<version>0.1.0-SNAPSHOT</version>
<name>core-java-collections-maps-6</name>
<packaging>jar</packaging>
<parent>
<artifactId>core-java-modules</artifactId>
<groupId>com.baeldung.core-java-modules</groupId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<properties>
<spring.version>5.2.5.RELEASE</spring.version>
</properties>
</project>

47
core-java-modules/core-java-collections-maps-6/src/main/java/com/baeldung/map/hashmapcopy/CopyingAHashMapToAnother.java Normal file
View File

@ -0,0 +1,47 @@
package com.baeldung.map.hashmapcopy;
import java.util.Map;
import com.google.common.collect.MapDifference;
import com.google.common.collect.Maps;
public class CopyingAHashMapToAnother {
public Map<String, String> copyByIteration(Map<String, String> sourceMap, Map<String, String> targetMap) {
for (Map.Entry<String, String> entry : sourceMap.entrySet()) {
if (!targetMap.containsKey(entry.getKey())) {
targetMap.put(entry.getKey(), entry.getValue());
}
}
return targetMap;
}
public Map<String, String> copyUsingPutAll(Map<String, String> sourceMap, Map<String, String> targetMap) {
sourceMap.keySet()
.removeAll(targetMap.keySet());
targetMap.putAll(sourceMap);
return targetMap;
}
public Map<String, String> copyUsingPutIfAbsent(Map<String, String> sourceMap, Map<String, String> targetMap) {
for (Map.Entry<String, String> entry : sourceMap.entrySet()) {
targetMap.putIfAbsent(entry.getKey(), entry.getValue());
}
return targetMap;
}
public Map<String, String> copyUsingPutIfAbsentForEach(Map<String, String> sourceMap, Map<String, String> targetMap) {
sourceMap.forEach(targetMap::putIfAbsent);
return targetMap;
}
public Map<String, String> copyUsingMapMerge(Map<String, String> sourceMap, Map<String, String> targetMap) {
sourceMap.forEach((key, value) -> targetMap.merge(key, value, (oldVal, newVal) -> oldVal));
return targetMap;
}
public Map<String, String> copyUsingGuavaMapDifference(Map<String, String> sourceMap, Map<String, String> targetMap) {
MapDifference<String, String> differenceMap = Maps.difference(sourceMap, targetMap);
targetMap.putAll(differenceMap.entriesOnlyOnLeft());
return targetMap;
}
}

68
core-java-modules/core-java-collections-maps-6/src/test/java/com/baeldung/map/hashmapcopy/CopyHashMapIntoAnotherUnitTest.java Normal file
View File

@ -0,0 +1,68 @@
package com.baeldung.map.hashmapcopy;
import java.util.HashMap;
import java.util.Map;
import org.junit.Assert;
import org.junit.Test;
import com.baeldung.map.hashmapcopy.CopyingAHashMapToAnother;
public class CopyHashMapIntoAnotherUnitTest {
@Test
public void givenSourceAndTargetMapsWhenIteratedOverThenCopyingSuccess(){
CopyingAHashMapToAnother obj = new CopyingAHashMapToAnother();
Assert.assertEquals(generateExpectedResultMap(), obj.copyByIteration(generateSourceMap(), generateTargetMap()));
}
@Test
public void givenSourceAndTargetMapsWhenUsedPutAllThenCopyingSuccess(){
CopyingAHashMapToAnother obj = new CopyingAHashMapToAnother();
Assert.assertEquals(generateExpectedResultMap(), obj.copyUsingPutAll(generateSourceMap(), generateTargetMap()));
}
@Test
public void givenSourceAndTargetMapsWhenUsedPutIfAbsentThenCopyingSuccess(){
CopyingAHashMapToAnother obj = new CopyingAHashMapToAnother();
Assert.assertEquals(generateExpectedResultMap(), obj.copyUsingPutIfAbsent(generateSourceMap(), generateTargetMap()));
Assert.assertEquals(generateExpectedResultMap(), obj.copyUsingPutIfAbsentForEach(generateSourceMap(), generateTargetMap()));
}
@Test
public void givenSourceAndTargetMapsWhenUsedMapMergeThenCopyingSuccess(){
CopyingAHashMapToAnother obj = new CopyingAHashMapToAnother();
Assert.assertEquals(generateExpectedResultMap(), obj.copyUsingMapMerge(generateSourceMap(), generateTargetMap()));
}
@Test
public void givenSourceAndTargetMapsWhenMapDifferenceUsedThenCopyingSuccess(){
CopyingAHashMapToAnother obj = new CopyingAHashMapToAnother();
Assert.assertEquals(generateExpectedResultMap(), obj.copyUsingGuavaMapDifference(generateSourceMap(), generateTargetMap()));
}
private Map<String, String> generateSourceMap(){
Map<String, String> sourceMap = new HashMap<>();
sourceMap.put("India", "Delhi");
sourceMap.put("United States", "Washington D.C.");
sourceMap.put("United Kingdom", "London DC");
return sourceMap;
}
private Map<String, String> generateTargetMap(){
Map<String, String> targetMap = new HashMap<>();
targetMap.put("Zimbabwe", "Harare");
targetMap.put("Norway", "Oslo");
targetMap.put("United Kingdom", "London");
return targetMap;
}
private Map<String, String> generateExpectedResultMap(){
Map<String, String> resultMap = new HashMap<>();
resultMap.put("India", "Delhi");
resultMap.put("United States", "Washington D.C.");
resultMap.put("United Kingdom", "London");
resultMap.put("Zimbabwe", "Harare");
resultMap.put("Norway", "Oslo");
return resultMap;
}
}

1
core-java-modules/pom.xml
View File

@ -132,6 +132,7 @@
<module>core-java-regex-2</module>
<module>core-java-uuid</module>
<module>pre-jpms</module>
<module>core-java-collections-maps-6</module>
</modules>
<dependencyManagement>