Utility Methods of Wrapper Classes in Java

Prerequisite: Wrapper Classes

The objective of the Wrapper class is to define several utility methods which are required for the primitive types. There are 4 utility methods for primitive type which is defined by the Wrapper class: 

1. valueOf() method:

We can use the valueOf() method to create a Wrapper object for a given primitive or String. There are 3 types of valueOf() methods: 

A. Wrapper valueOf(String s): Every wrapper class except Character class contains a static valueOf() method to create Wrapper class object for a given String.

Syntax:

public static Wrapper valueOf(String s);

Java

// Java program to illustrate valueof() Method

class GFG {
    public static void main(String[] args)
    {
        Integer I = Integer.valueOf("10");
        System.out.println(I);

        Double D = Double.valueOf("10.0");
        System.out.println(D);

        Boolean B = Boolean.valueOf("true");
        System.out.println(B);

        // Here we will get RuntimeException
        Integer I1 = Integer.valueOf("ten");
    }
}

Output: 

10
10.0
true
Exception in thread "main" java.lang.NumberFormatException: For input string: "ten"

B. Wrapper valueOf(String s, int radix): Every Integral Wrapper class Byte, Short, Integer, Long) contains the following valueOf() method to create a Wrapper object for the given String with specified radix. The range of the radix is 2 to 36.

Syntax:

public static Wrapper valueOf(String s, int radix)

Java

// Java program to illustrate valueof() Method

class GFG {
    public static void main(String[] args)
    {
        Integer I = Integer.valueOf("1111", 2);
        System.out.println(I);

        Integer I1 = Integer.valueOf("1111", 4);
        System.out.println(I1);
    }
}

Output

15
85

3. Wrapper valueOf(primitive p): Every Wrapper class including the Character class contains the following method to create a Wrapper object for the given primitive type.

Syntax:

public static Wrapper valueOf(primitive p);

Java

// Java program to illustrate valueof() Method

class GFG {
    public static void main(String[] args)
    {
        Integer I = Integer.valueOf(10);
        Double D = Double.valueOf(10.5);
        Character C = Character.valueOf('a');

        System.out.println(I);
        System.out.println(D);
        System.out.println(C);
    }
}

Output

10
10.5
a

2. xxxValue() Method

We can use xxxValue() methods to get the primitive for the given Wrapper Object. Every number type Wrapper class( Byte, Short, Integer, Long, Float, Double) contains the following 6 methods to get primitive for the given Wrapper object: 

1. public byte byteValue()
2. public short shortValue()
3. public int intValue()
4. public long longValue()
5. public float floatValue()
6. public float doubleValue()

3. parseXxx() Method

We can use parseXxx() methods to convert String to primitive. There are two types of parseXxx() methods: 

A. primitive parseXxx(String s): Every Wrapper class except the character class contains the following parseXxx() method to find primitive for the given String object.

Syntax:

public static primitive parseXxx(String s);

Java

// Java program to illustrate parseXxx() Method

class GFG {
    public static void main(String[] args)
    {
        int i = Integer.parseInt("10");
        double d = Double.parseDouble("10.5");
        boolean b = Boolean.parseBoolean("true");

        System.out.println(i);
        System.out.println(d);
        System.out.println(b);
    }
}

Output

10
10.5
true

B. parseXxx(String s, int radix): Every Integral type Wrapper class (Byte, Short, Integer, Long) contains the following parseXxx() method to convert specified radix String to primitive.

Syntax:

public static primitive parseXxx(String s, int radix);

Java

// Java program to illustrate parseXxx() Method

class GFG {
    public static void main(String[] args)
    {
        int i = Integer.parseInt("1000", 2);
        long l = Long.parseLong("1111", 4);

        System.out.println(i);
        System.out.println(l);
    }
}

Output

8
85

4. toString() Method

We can use the toString() method to convert the Wrapper object or primitive to String. There are a few forms of the toString() method: 

A. public String toString(): Every wrapper class contains the following toString() method to convert Wrapper Object to String type. 

Syntax:

public String toString();

Java

// Java program to illustrate toString() Method

class GFG {
    public static void main(String[] args)
    {
        Integer I = new Integer(10);
        String s = I.toString();
        System.out.println(s);
    }
}

Output: 

10

B. toString(primitive p): Every Wrapper class including the Character class contains the following static toString() method to convert primitive to String.

Syntax:

public static String toString(primitive p);

Java

// Java program to illustrate toString()

class GFG {
    public static void main(String[] args)
    {
        String s = Integer.toString(10);
        System.out.println(s);

        String s1 = Character.toString('a');
        System.out.println(s1);
    }
}

Output

10
a

C. toString(primitive p, int radix): Integer and Long classes contain the following toString() method to convert primitive to specified radix String.

Syntax:

public static String toString(primitive p, int radix);

Java

// Java program to illustrate toString() Method

class GFG {
    public static void main(String[] args)
    {
        String s = Integer.toString(15, 2);
        System.out.println(s);

        String s1 = Long.toString(11110000, 4);
        System.out.println(s1);
    }
}

Output

1111
222120121300