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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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