Java Collections disjoint() Method

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Description

The Java Collections disjoint(Collection<?>, Collection<?>) method is used to return 'true' if the two specified collections have no elements in common.

Declaration

Following is the declaration for java.util.Collections.disjoint() method.

public static boolean disjoint(Collection<?> c1,Collection<?> c2)

Parameters

• c1 − This is a collection.

• c2 − This is another collection.

Return Value

NA

Exception

NullPointerException − This is thrown if either collection is null.

Comparing Lists of Integers for Common Values Example

The following example shows the usage of Java Collection disjoint(Collection,Collection) method to compare a list of Integers. We've created two lists with some integers. Using disjoint(Collection,Collection) method, we're comparing content of one list to another for any common element then result is printed.

 
package com.tutorialspoint;

import java.util.*;

public class CollectionsDemo {
   public static void main(String args[]) {

      // create two lists    
      List<Integer> srclst = new ArrayList<>();
      List<Integer> destlst = new ArrayList<>();

      // populate two lists
      srclst.add(1);
      srclst.add(2);
      srclst.add(3);

      destlst.add(4);
      destlst.add(5);
      destlst.add(6);
      destlst.add(7);

      // check elements in both collections
      boolean iscommon = Collections.disjoint(srclst, destlst);

      System.out.println("No commom elements: "+iscommon);
   }    
}

Output

Let us compile and run the above program, this will produce the following result.

No commom elements: true

Comparing Lists of Strings for Common Values Example

The following example shows the usage of Java Collection disjoint(Collection,Collection) method to compare a list of Strings. We've created two lists with some strings. Using disjoint(Collection,Collection) method, we're comparing content of one list to another for any common element then result is printed.

 
package com.tutorialspoint;

import java.util.*;

public class CollectionsDemo {
   public static void main(String args[]) {

      // create two lists    
      List<String> srclst = new ArrayList<>();
      List<String> destlst = new ArrayList<>();

      // populate two lists
      srclst.add("A");
      srclst.add("B");
      srclst.add("C");

      destlst.add("D");
      destlst.add("E");
      destlst.add("F");
      destlst.add("G");

      // check elements in both collections
      boolean iscommon = Collections.disjoint(srclst, destlst);

      System.out.println("No commom elements: "+iscommon);
   }    
}

Output

Let us compile and run the above program, this will produce the following result.

No commom elements: true

Comparing Lists of Objects for Common Values Example

The following example shows the usage of Java Collection disjoint(Collection,Collection) method to compare a list of Student objects. We've created two lists with some student objects. Using disjoint(Collection,Collection) method, we're comparing content of one list to another for any common element then result is printed.

 
package com.tutorialspoint;

import java.util.*;

public class CollectionsDemo {
   public static void main(String args[]) {

      // create two lists    
      List<Student> srclst = new ArrayList<>(Arrays.asList(new Student(1, "Julie"),
         new Student(2, "Robert"), new Student(3, "Adam")));
      List<Student> destlst = new ArrayList<>(Arrays.asList(new Student(4, "Jene"),
         new Student(5, "Julie"), new Student(6, "Trus")));

      // check elements in both collections
      boolean iscommon = Collections.disjoint(srclst, destlst);

      System.out.println("No commom elements: "+iscommon);
   }    
}
class Student {
   int rollNo;
   String name;

   Student(int rollNo, String name){
      this.rollNo = rollNo;
      this.name = name;
   }

   @Override
   public String toString() {
      return "[ " + this.rollNo + ", " + this.name + " ]";
   }
   
   @Override
   public boolean equals(Object obj) {
      Student s = (Student)obj;
      return this.rollNo == s.rollNo && this.name.equalsIgnoreCase(s.name);
   }
}

Output

Let us compile and run the above program, this will produce the following result.

No commom elements: true