Immutable Class in java

Here is the example, how to create immutable Class in java

package com.nitesh;

import java.util.Collections;
import java.util.Date;
import java.util.List;

/**
 * Don't provide "setter" methods — methods that modify fields or objects referred to by fields.
 * Make all fields final and private.
 * Don't allow subclasses to override methods. The simplest way to do this is to declare the class as final. A more sophisticated approach is 
 * to make the constructor private and construct instances in factory methods.
 * If the instance fields include references to mutable objects, don't allow those objects to be changed:
 * Don't provide methods that modify the mutable objects.
 * Don't share references to the mutable objects. Never store references to external, mutable objects passed to the constructor; if necessary, create copies, 
 * and store references to the copies. Similarly, create copies of your internal mutable objects when necessary to avoid returning the originals in your methods.
 * @author Nitesh.Gupta
 *
 */
public final class MyImmuatable {
/**
* Final Integer field, Integer is anyways immutable
*/
private final Integer immutableField1;
/**
* Final String field
*/
private final String immutableField2;
/**
* Final Date object which is mutable and need to be taken care explicitly
*/
private final Date immutableField3;
/**
* Final List Object which is mutable 
*/
private final List immutableField4;
/**
* Constructor which is taking all inputs through parameters
* @param immutableField1
* @param immutableField2
* @param immutableField3
* @param immutableField4
*/
public  MyImmuatable (Integer immutableField1, String immutableField2, Date immutableField3,List immutableField4){
this.immutableField1 = immutableField1;
this.immutableField2 = immutableField2;
this.immutableField3 = new Date(immutableField3.getTime());
this.immutableField4 = Collections.unmodifiableList(immutableField4);
}

public Integer getImmutableField1() {
return immutableField1;
}

public String getImmutableField2() {
return immutableField2;
}

public Date getImmutableField3() {
return immutableField3;
}

public List getImmutableField4() {
return immutableField4;
}

@Override
public String toString() {
return "MyImmuatable [immutableField1=" + immutableField1 + ", immutableField2=" + immutableField2
+ ", immutableField3=" + immutableField3 + ", immutableField4=" + immutableField4 + "]";
}


}