Objects class provides helper functions applicable to all objects such as equals, hashCode, etc.
Class Declaration
Following is the declaration for com.google.common.base.Objects class −
@GwtCompatible public final class Objects extends Object
Class Methods
| Sr.No | Method & Description |
|---|---|
| 1 | static boolean equal(Object a, Object b)Determines whether two possibly-null objects are equal. |
| 2 | static <T> T firstNonNull(T first, T second)Deprecated. Use MoreObjects.firstNonNull(T, T) instead. This method is scheduled for removal in June 2016. |
| 3 | static int hashCode(Object… objects)Generates a hash code for multiple values. |
| 4 | static Objects.ToStringHelper toStringHelper(Class<?> clazz)Deprecated. Use MoreObjects.toStringHelper(Class) instead. This method is scheduled for removal in June 2016 |
| 5 | static Objects.ToStringHelper toStringHelper(Object self)Deprecated. Use MoreObjects.toStringHelper(Object) instead. This method is scheduled for removal in June 2016. |
| 6 | static Objects.ToStringHelper toStringHelper(String className)Deprecated. Use MoreObjects.toStringHelper(String) instead. This method is scheduled for removal in June 2016. |
Methods Inherited
This class inherits methods from the following class −
- java.lang.Object
Example of Objects Class
Create the following java program using any editor of your choice in say C:/> Guava.
GuavaTester.java
import com.google.common.base.Objects;
public class GuavaTester {
public static void main(String args[]) {
Student s1 = new Student("Mahesh", "Parashar", 1, "VI");
Student s2 = new Student("Suresh", null, 3, null);
System.out.println(s1.equals(s2));
System.out.println(s1.hashCode());
System.out.println(
Objects.toStringHelper(s1)
.add("Name",s1.getFirstName()+" " + s1.getLastName())
.add("Class", s1.getClassName())
.add("Roll No", s1.getRollNo())
.toString());
}
}
class Student {
private String firstName;
private String lastName;
private int rollNo;
private String className;
public Student(String firstName, String lastName, int rollNo, String className) {
this.firstName = firstName;
this.lastName = lastName;
this.rollNo = rollNo;
this.className = className;
}
@Override
public boolean equals(Object object) {
if(!(object instanceof Student) || object == null) {
return false;
}
Student student = (Student)object;
// no need to handle null here
// Objects.equal("test", "test") == true
// Objects.equal("test", null) == false
// Objects.equal(null, "test") == false
// Objects.equal(null, null) == true
return Objects.equal(firstName, student.firstName) // first name can be null
&& Objects.equal(lastName, student.lastName) // last name can be null
&& Objects.equal(rollNo, student.rollNo)
&& Objects.equal(className, student.className); // class name can be null
}
@Override
public int hashCode() {
//no need to compute hashCode by self
return Objects.hashCode(className,rollNo);
}
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public int getRollNo() {
return rollNo;
}
public void setRollNo(int rollNo) {
this.rollNo = rollNo;
}
public String getClassName() {
return className;
}
public void setClassName(String className) {
this.className = className;
}
}
Verify the Result
Compile the class using javac compiler as follows −
C:\Guava>javac GuavaTester.java
Now run the GuavaTester to see the result.
C:\Guava>java GuavaTester
See the result.
false
85871
Student{Name=Mahesh Parashar, Class=VI, Roll No=1}
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