布尔类|番石榴|爪哇

原文:https://www.geeksforgeeks.org/booleans-class-guava-java/

布尔是一个用于基元类型布尔的实用程序类。它提供了属于布尔原语的静态实用方法，这些方法在布尔或数组中都找不到。

*申报:*

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

下面给出的是番石榴类提供的一些方法: 例外:****

  • *确保容量: 如果最小长度或填充值为负，则显示“异常”。*
  • *to array:NullPointerException如果集合或其任何元素为空。*

下表显示了番石榴树类提供的一些其他方法: 下面给出了一些示例，显示了番石榴树类方法的实现: 示例 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));
    }
}

输出:

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 occurence of false
        System.out.println(Booleans.indexOf(arr, false));
    }
}

输出:

1

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