Java Boolean Class
Last modified: April 13, 2025
The java.lang.Boolean class wraps a value of the primitive type
boolean in an object. This wrapper class provides methods for
converting between boolean values and strings, as well as other utilities.
Boolean objects contain a single field whose type is boolean. This
class provides constants TRUE and FALSE representing
the primitive boolean values. It also contains methods for string conversion and
comparison operations.
Boolean Class Methods
The Boolean class provides several static and instance methods for working with
boolean values. Key methods include valueOf, parseBoolean,
booleanValue, toString, and compare.
public final class Boolean implements java.io.Serializable,
Comparable<Boolean> {
public static final Boolean TRUE = new Boolean(true);
public static final Boolean FALSE = new Boolean(false);
public Boolean(boolean value) {...}
public Boolean(String s) {...}
public static boolean parseBoolean(String s) {...}
public boolean booleanValue() {...}
public static Boolean valueOf(boolean b) {...}
public static Boolean valueOf(String s) {...}
public static String toString(boolean b) {...}
public String toString() {...}
public int hashCode() {...}
public boolean equals(Object obj) {...}
public static int compare(boolean x, boolean y) {...}
public int compareTo(Boolean b) {...}
public static boolean logicalAnd(boolean a, boolean b) {...}
public static boolean logicalOr(boolean a, boolean b) {...}
public static boolean logicalXor(boolean a, boolean b) {...}
}
The code above shows the main methods and constants provided by the Boolean class. These methods allow conversion between primitive and object forms and provide logical operations.
Creating Boolean Objects
Boolean objects can be created using constructors or the valueOf
method. The constructors are rarely used directly since Java 5 due to autoboxing.
package com.zetcode;
public class Main {
public static void main(String[] args) {
// Using constructors (less common)
Boolean bool1 = new Boolean(true);
Boolean bool2 = new Boolean("true");
Boolean bool3 = new Boolean("TRUE");
Boolean bool4 = new Boolean("false");
// Using valueOf (recommended)
Boolean bool5 = Boolean.valueOf(true);
Boolean bool6 = Boolean.valueOf("true");
Boolean bool7 = Boolean.valueOf("TRUE");
Boolean bool8 = Boolean.valueOf("false");
System.out.println("bool1: " + bool1);
System.out.println("bool2: " + bool2);
System.out.println("bool3: " + bool3);
System.out.println("bool4: " + bool4);
System.out.println("bool5: " + bool5);
System.out.println("bool6: " + bool6);
System.out.println("bool7: " + bool7);
System.out.println("bool8: " + bool8);
}
}
This example demonstrates different ways to create Boolean objects. The
constructors and valueOf methods accept both primitive boolean
values and strings. String values are case-insensitive for "true".
parseBoolean Method
The parseBoolean method parses a string argument into a boolean
primitive. It returns true if the string equals "true" (case
insensitive), otherwise false.
package com.zetcode;
public class Main {
public static void main(String[] args) {
boolean b1 = Boolean.parseBoolean("True");
boolean b2 = Boolean.parseBoolean("true");
boolean b3 = Boolean.parseBoolean("TRUE");
boolean b4 = Boolean.parseBoolean("false");
boolean b5 = Boolean.parseBoolean("FALSE");
boolean b6 = Boolean.parseBoolean("yes");
boolean b7 = Boolean.parseBoolean("1");
System.out.println("b1: " + b1);
System.out.println("b2: " + b2);
System.out.println("b3: " + b3);
System.out.println("b4: " + b4);
System.out.println("b5: " + b5);
System.out.println("b6: " + b6);
System.out.println("b7: " + b7);
}
}
This example shows how parseBoolean converts strings to boolean
values. Only the exact string "true" (case-insensitive) returns true. All other
strings, including "yes" and "1", return false.
booleanValue and toString Methods
The booleanValue method returns the primitive boolean value of a
Boolean object. The toString methods convert boolean values to
their string representations.
package com.zetcode;
public class Main {
public static void main(String[] args) {
Boolean boolObj1 = Boolean.TRUE;
Boolean boolObj2 = Boolean.FALSE;
// Using booleanValue()
boolean prim1 = boolObj1.booleanValue();
boolean prim2 = boolObj2.booleanValue();
// Using toString()
String str1 = boolObj1.toString();
String str2 = boolObj2.toString();
String str3 = Boolean.toString(true);
String str4 = Boolean.toString(false);
System.out.println("prim1: " + prim1);
System.out.println("prim2: " + prim2);
System.out.println("str1: " + str1);
System.out.println("str2: " + str2);
System.out.println("str3: " + str3);
System.out.println("str4: " + str4);
}
}
This example demonstrates converting between Boolean objects, primitive booleans,
and strings. The booleanValue method extracts the primitive value,
while toString converts boolean values to their string equivalents.
Logical Operations
The Boolean class provides static methods for logical operations: logicalAnd,
logicalOr, and logicalXor. These perform AND, OR, and
XOR operations on boolean values.
package com.zetcode;
public class Main {
public static void main(String[] args) {
boolean a = true;
boolean b = false;
boolean andResult = Boolean.logicalAnd(a, b);
boolean orResult = Boolean.logicalOr(a, b);
boolean xorResult = Boolean.logicalXor(a, b);
System.out.println("a AND b: " + andResult);
System.out.println("a OR b: " + orResult);
System.out.println("a XOR b: " + xorResult);
// More complex expressions
boolean expr1 = Boolean.logicalAnd(
Boolean.logicalOr(a, b),
Boolean.logicalXor(a, b)
);
System.out.println("(a OR b) AND (a XOR b): " + expr1);
}
}
This example shows the logical operations provided by the Boolean class. These
methods are equivalent to using the &&, ||, and
^ operators but are useful in functional programming contexts.
Comparison Methods
The Boolean class provides compare and compareTo
methods for comparing boolean values. These methods are useful for sorting and
ordering operations.
package com.zetcode;
public class Main {
public static void main(String[] args) {
// Using compare (static method)
int result1 = Boolean.compare(true, false);
int result2 = Boolean.compare(false, true);
int result3 = Boolean.compare(true, true);
// Using compareTo (instance method)
Boolean bool1 = Boolean.TRUE;
Boolean bool2 = Boolean.FALSE;
int result4 = bool1.compareTo(bool2);
int result5 = bool2.compareTo(bool1);
int result6 = bool1.compareTo(bool1);
System.out.println("compare(true, false): " + result1);
System.out.println("compare(false, true): " + result2);
System.out.println("compare(true, true): " + result3);
System.out.println("TRUE.compareTo(FALSE): " + result4);
System.out.println("FALSE.compareTo(TRUE): " + result5);
System.out.println("TRUE.compareTo(TRUE): " + result6);
}
}
This example demonstrates boolean comparisons. The methods return positive values when the first argument is true and the second is false, negative values for the opposite case, and zero when both values are equal.
Using Boolean in Collections
Boolean objects are commonly used in Java collections since primitive types cannot be stored directly. This example shows Boolean usage with ArrayList and HashMap.
package com.zetcode;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class Main {
public static void main(String[] args) {
// Using Boolean in a List
List<Boolean> boolList = new ArrayList<>();
boolList.add(true);
boolList.add(Boolean.FALSE);
boolList.add(Boolean.parseBoolean("true"));
System.out.println("Boolean List:");
for (Boolean b : boolList) {
System.out.println(b);
}
// Using Boolean in a Map
Map<String, Boolean> settings = new HashMap<>();
settings.put("autoSave", true);
settings.put("darkMode", false);
settings.put("notifications", Boolean.valueOf("TRUE"));
System.out.println("\nSettings Map:");
for (Map.Entry<String, Boolean> entry : settings.entrySet()) {
System.out.println(entry.getKey() + ": " + entry.getValue());
}
}
}
This example demonstrates storing Boolean objects in collections. The ArrayList stores multiple Boolean values, while the HashMap uses them as values associated with string keys. Autoboxing automatically converts between primitive and object forms.
Source
Java Boolean Class Documentation
In this article, we've covered all major aspects of the Java Boolean class with practical examples. Understanding these methods is essential for working with boolean values in object-oriented contexts and collections.
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