Java Booleans类

Booleans 是原始类型Boolean的一个实用类。它提供了与布尔基元有关的 静态实用方法 ，这些方法 在布尔或数组中都没有找到。

声明 :

@GwtCompatible(emulated=true)
public final class Booleans
extends Object

以下是Guava Booleans类提供的一些方法：

异常情况

• ensureCapacity : 如果minLength或padding为负数，则出现IllegalArgumentException。
• toArray : 如果集合或其任何元素为空，则出现NullPointerException。

下表显示了Guava Booleans类提供的一些其他方法：

下面给出了一些例子，显示了Guava Booleans类方法的实现。

例子1 :

// Java code to show implementation
// of Guava Booleans.asList() method
 
import com.google.common.primitives.Booleans;
import java.util.*;
 
class GFG {
    // Driver method
    public static void main(String[] args)
    {
        boolean arr[] = { true, false, true, false, true };
 
        // Using Booleans.asList() method which
        // converts array of primitives to array of objects
        List<Boolean> myList = Booleans.asList(arr);
 
        // Displaying the elements
        System.out.println(myList);
    }
}

输出:

[true, false, true, false, true]

例2 :

// Java code to show implementation
// of Guava Booleans.toArray() method
 
import com.google.common.primitives.Booleans;
import java.util.*;
 
class GFG {
    // Driver method
    public static void main(String[] args)
    {
        List<Boolean> myList = Arrays.asList(true, false, true, false, true);
 
        // Using Booleans.toArray() method which
        // converts a List of Booleans to an
        // array of boolean
        boolean[] arr = Booleans.toArray(myList);
 
        // Displaying the elements
        System.out.println(Arrays.toString(arr));
    }
}

输出:

[true, false, true, false, true]

例3 :

// Java code to show implementation
// of Guava Booleans.concat() method
 
import com.google.common.primitives.Booleans;
import java.util.*;
 
class GFG {
    // Driver method
    public static void main(String[] args)
    {
        boolean[] arr1 = { true, false, true };
        boolean[] arr2 = { false, true };
 
        // Using Booleans.concat() method which
        // combines arrays from specified
        // arrays into a single array
        boolean[] arr = Booleans.concat(arr1, arr2);
 
        // Displaying the elements
        System.out.println(Arrays.toString(arr));
    }
}

输出:

[true, false, true, false, true]

例4 :

// Java code to show implementation
// of Guava Booleans.contains() method
 
import com.google.common.primitives.Booleans;
 
class GFG {
    // Driver method
    public static void main(String[] args)
    {
        boolean[] arr = { true, false, true, false, true };
 
        // Using Booleans.contains() method which
        // checks if element is present in array
        // or not
        System.out.println(Booleans.contains(arr, true));
        System.out.println(Booleans.contains(arr, false));
    }
}

产出 :

true
true

例5 :

// Java code to show implementation
// of Guava Booleans.compare() method
 
import com.google.common.primitives.Booleans;
 
class GFG {
    // Driver method
    public static void main(String[] args)
    {
        // To compare true vs true
        System.out.println(Booleans.compare(true, true));
    }
}

输出:

0

例6 :

// Java code to show implementation
// of Guava Booleans.indexOf() method
 
import com.google.common.primitives.Booleans;
 
class GFG {
    // Driver method
    public static void main(String[] args)
    {
        boolean[] arr = { true, false, true, false, true };
 
        // To print index of first occurrence of false
        System.out.println(Booleans.indexOf(arr, false));
    }
}

输出:

1