Archive for category JAVA

create directory and file

/**
* Create directory and file if not exists
*/
public File createDirectory() throws IOException {
File file = new File(“C:\\report”);
if (!file.exists()) {
file.mkdir();
}

file = new File(“C:\\report\\report.xls”);
if (!file.exists()) {
file.createNewFile();
}
return file;
}

 

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remove duplicate from java list

For object comparison  override equal and hashcode

such as

User.java
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((id == null) ? 0 : id.hashCode());
return result;
}

@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
BaseEntity other = (BaseEntity) obj;
if (id == null) {
if (other.id != null)
return false;
} else if (!id.equals(other.id))
return false;
return true;
}

List updatedMultListWithoutDuplicate = new ArrayList<>(new HashSet<>(duplicatedMultList));

http://www.baeldung.com/java-remove-duplicates-from-list

https://www.dotnetperls.com/duplicates-java

 

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Using Matcher search in list

String value=”java”;

List result = searchIn(list, new Matcher() {
public boolean matches(MyObjectp) {
return p.getName().equals(value);
}
});

public List searchIn(List list, Matcher m) {
List r = new ArrayList();
for (T t : list) {
if (m.matches(t)) {
r.add(t);
}
}
return r;
}
interface Matcher {
public boolean matches( T t );
}

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