Java - Boolean getBoolean() method

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Description

The Java Boolean getBoolean(String name) returns true if and only if the system property named by the argument exists and is equal to the string "true". A system property is accessible through getProperty, a method defined by the System class.

If there is no property with the specified name, or if the specified name is empty or null, then false is returned.

Declaration

Following is the declaration for java.lang.Boolean.getBoolean() method

public static boolean getBoolean(String name)

Parameters

name − the system property name

Return Value

This method returns the boolean value of the system property.

Exception

NA

Example 1

The following example shows the usage of Boolean getBoolean() method where System property exists as true and a random string "abcd".

package com.tutorialspoint;
public class BooleanDemo {
   public static void main(String[] args) {

      // create 2 boolean primitives bool1, bool2
      boolean bool1, bool2;

      /**
       *  using System class's setProprty method, set the values of
       *  system properties demo1, demo2.
       */
      System.setProperty("demo1","true");
      System.setProperty("demo2","abcd");

      // retrieve value of system properties to s1, s2
      String s1 = System.getProperty("demo1");
      String s2 = System.getProperty("demo2");

      // assign result of getBoolean on demo1, demo2 to bool1, bool2
      bool1 = Boolean.getBoolean("demo1");
      bool2 = Boolean.getBoolean("demo2");

      String str1 = "boolean value of system property demo1 is " + bool1;
      String str2 = "System property value of demo1 is " + s1;
      String str3 = "boolean value of system property demo2 is " + bool2;
      String str4 = "System property value of demo2 is " + s2;

      // print bool1, bool2 and s1, s2 values
      System.out.println( str1 );
      System.out.println( str2 );
      System.out.println( str3 );
      System.out.println( str4 );
   }
}

Output

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

boolean value of system property demo1 is true
System property value of demo1 is true
boolean value of system property demo2 is false
System property value of demo2 is abcd

Example 2

The following example shows the usage of Boolean getBoolean() method where System property exists as true and a random string "abcd".

package com.tutorialspoint;
public class BooleanDemo {
   public static void main(String[] args) {

      // create 2 boolean primitives bool1, bool2
      boolean bool1, bool2;

      /**
       *  using System class's setProprty method, set the values of
       *  system properties demo1, demo2.
       */
      System.setProperty("demo1","true");
      System.setProperty("demo2","abcd");

      // retrieve value of system properties to s1, s2
      String s1 = System.getProperty("demo1");
      String s2 = System.getProperty("demo2");

      // assign result of getBoolean on demo1, demo2 to bool1, bool2
      bool1 = Boolean.getBoolean("demo1");
      bool2 = Boolean.getBoolean("demo2");

      String str1 = "boolean value of system property demo1 is " + bool1;
      String str2 = "System property value of demo1 is " + s1;
      String str3 = "boolean value of system property demo2 is " + bool2;
      String str4 = "System property value of demo2 is " + s2;

      // print bool1, bool2 and s1, s2 values
      System.out.println( str1 );
      System.out.println( str2 );
      System.out.println( str3 );
      System.out.println( str4 );
   }
}

Output

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

boolean value of system property demo1 is true
System property value of demo1 is true
boolean value of system property demo2 is false
System property value of demo2 is abcd

Example 3

The following example shows the usage of Boolean getBoolean() method where System property is not present.

package com.tutorialspoint;
public class BooleanDemo {
   public static void main(String[] args) {

      // create 2 boolean primitives bool1, bool2
      boolean bool1, bool2;

      // retrieve value of system properties to s1, s2
      String s1 = System.getProperty("demo1");
      String s2 = System.getProperty("demo2");

      // assign result of getBoolean on demo1, demo2 to bool1, bool2
      bool1 = Boolean.getBoolean("demo1");
      bool2 = Boolean.getBoolean("demo2");

      String str1 = "boolean value of system property demo1 is " + bool1;
      String str2 = "System property value of demo1 is " + s1;
      String str3 = "boolean value of system property demo2 is " + bool2;
      String str4 = "System property value of demo2 is " + s2;

      // print bool1, bool2 and s1, s2 values
      System.out.println( str1 );
      System.out.println( str2 );
      System.out.println( str3 );
      System.out.println( str4 );
   }
}

Output

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

boolean value of system property demo1 is false
System property value of demo1 is null
boolean value of system property demo2 is false
System property value of demo2 is null