Guava - Useful Classes

Guava - Collection Utilities

Guava - String Utilities

Guava - Primitive Utilities

Guava - Math Utilities

Guava - Useful Resources

Guava - Ints Class

Quiz

Ints is a utility class for primitive type int.

Class Declaration

Following is the declaration for com.google.common.primitives.Ints class −

@GwtCompatible
public final class Ints
   extends Object

Sr.No	Field & Description
1	static int BYTES The number of bytes required to represent a primitive int value.
2	static int MAX_POWER_OF_TWO The largest power of two that can be represented as a int.

Sr.No

Field & Description

static int BYTES

The number of bytes required to represent a primitive int value.

static int MAX_POWER_OF_TWO

The largest power of two that can be represented as a int.

Sr.No	Method & Description
1	static List<Integer> asList(int... backingArray) Returns a fixed-size list backed by the specified array, similar to Arrays.asList(Object[]).
2	static int checkedCast(long value) Returns the int value that is equal to value, if possible.
3	static int compare(int a, int b) Compares the two specified int values.
4	static int[] concat(int[]... arrays) Returns the values from each provided array combined into a single array.
5	static boolean contains(int[] array, int target) Returns true if target is present as an element anywhere in array.
6	static int[] ensureCapacity(int[] array, int minLength, int padding) Returns an array containing the same values as array, but guaranteed to be of a specified minimum length.
7	static int fromByteArray(byte[] bytes) Returns the int value whose big-endian representation is stored in the first 4 bytes of bytes; equivalent to ByteBuffer.wrap(bytes).getInt().
8	static int fromBytes(byte b1, byte b2, byte b3, byte b4) Returns the int value whose byte representation is the given 4 bytes, in big-endian order; equivalent to Ints.fromByteArray(new byte[] {b1, b2, b3, b4}).
9	static int hashCode(int value) Returns a hash code for value; equal to the result of invoking ((Integer) value).hashCode().
10	static int indexOf(int[] array, int target) Returns the index of the first appearance of the value target in array.
11	static int indexOf(int[] array, int[] target) Returns the start position of the first occurrence of the specified target within array, or -1 if there is no such occurrence.
12	static String join(String separator, int... array) Returns a string containing the supplied int values separated by separator.
13	static int lastIndexOf(int[] array, int target) Returns the index of the last appearance of the value target in array.
14	static Comparator<int[]> lexicographicalComparator() Returns a comparator that compares two int arrays lexicographically.
15	static int max(int... array) Returns the greatest value present in array.
16	static int min(int... array) Returns the least value present in array.
17	static int saturatedCast(long value) Returns the int nearest in value to value.
18	static Converter<String,Integer> stringConverter() Returns a serializable converter object that converts between strings and integers using Integer.decode(java.lang.String) and Integer.toString().
19	static int[] toArray(Collection<? extends Number> collection) Returns an array containing each value of collection, converted to a int value in the manner of Number.intValue().
20	static byte[] toByteArray(int value) Returns a big-endian representation of value in a 4-element byte array; equivalent to ByteBuffer.allocate(4).putInt(value).array().
21	static Integer tryParse(String string) Parses the specified string as a signed decimal integer value.

Methods Inherited

This class inherits methods from the following class −

java.lang.Object

Example - Converting Array of Int to List and vice versa

GuavaTester.java

package com.tutorialspoint;

import java.util.List;

import com.google.common.primitives.Ints;

public class GuavaTester {

   public static void main(String args[]) {
      GuavaTester tester = new GuavaTester();
      tester.testInts();
   }

   private void testInts() {
      int[] intArray = {1,2,3,4,5,6,7,8,9};

      //convert array of primitives to array of objects
      List<Integer> objectArray = Ints.asList(intArray);
      System.out.println(objectArray.toString());

      //convert array of objects to array of primitives
      intArray = Ints.toArray(objectArray);
      System.out.print("[ ");
      
      for(int i = 0; i< intArray.length ; i++) {
         System.out.print(intArray[i] + " ");
      }
      
      System.out.println("]");
   }
}

Verify the Result

Run the GuavaTester and verify the output −

[1, 2, 3, 4, 5, 6, 7, 8, 9]
[ 1 2 3 4 5 6 7 8 9 ]

Example - Checking if Element is Present in the Int Array

GuavaTester.java

package com.tutorialspoint;

import com.google.common.primitives.Ints;

public class GuavaTester {

   public static void main(String args[]) {
      GuavaTester tester = new GuavaTester();
      tester.testInts();
   }

   private void testInts() {
      int[] intArray = {1,2,3,4,5,6,7,8,9};

      //check if element is present in the list of primitives or not
      System.out.println("5 is in list? " + Ints.contains(intArray, 5));
	  System.out.println("10 is in list? " + Ints.contains(intArray, 10));
   }
}

Verify the Result

Run the GuavaTester and verify the output −

5 is in list? true
10 is in list? false

Example - Getting Minimum/Maximum of Int Array

GuavaTester.java

package com.tutorialspoint;

import com.google.common.primitives.Ints;

public class GuavaTester {

   public static void main(String args[]) {
      GuavaTester tester = new GuavaTester();
      tester.testInts();
   }

   private void testInts() {
      int[] intArray = {1,2,3,4,5,6,7,8,9};
      //Returns the minimum		
      System.out.println("Min: " + Ints.min(intArray));

      //Returns the maximum		
      System.out.println("Max: " + Ints.max(intArray));

      //get the byte array from an integer
      byte[] byteArray = Ints.toByteArray(20000);
      
      for(int i = 0; i< byteArray.length ; i++) {
         System.out.print(byteArray[i] + " ");
      }
   }
}

Verify the Result

Run the GuavaTester and verify the output −

Min: 1
Max: 9
0 0 78 32

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