Java AbstractList equals()用法及代码示例

java.util.AbstractList 类的 equals() 方法用于比较指定对象与此列表是否相等。当且仅当指定对象也是一个列表时返回 true，两个列表具有相同的大小，并且两个列表中所有对应的元素对都相等。 (如果 (e1==null ? e2==null:e1.equals(e2)) 两个元素 e1 和 e2 相等。)换句话说，如果两个列表以相同的顺序包含相同的元素，则它们被定义为相等.

用法:

public boolean equals(Object o)

参数：此方法将对象 o 作为参数来比较与此列表是否相等。

Returns Value:如果指定的对象等于此列表，则此方法返回 true。

以下是说明 equals() 方法的示例。

范例1：


// Java program to demonstrate
// equals() method
// for String value
  
import java.util.*;
  
public class GFG1 {
    public static void main(String[] argv)
        throws Exception
    {
  
        try {
  
            // Creating object of AbstractList<String>
            AbstractList<String>
                arrlist1 = new ArrayList<String>();
  
            // Populating arrlist1
            arrlist1.add("A");
            arrlist1.add("B");
            arrlist1.add("C");
            arrlist1.add("D");
            arrlist1.add("E");
  
            // print arrlist1
            System.out.println("First ArrayListlist:"
                               + arrlist1);
  
            // Creating another object of AbstractList<String>
            AbstractList<String>
                arrlist2 = new ArrayList<String>();
  
            // Populating arrlist2
            arrlist2.add("A");
            arrlist2.add("B");
            arrlist2.add("C");
            arrlist2.add("D");
            arrlist2.add("E");
  
            // print arrlist2
            System.out.println("Second ArrayList:"
                               + arrlist2);
  
            // comparing first ArrayList to another
            // using equals() method
            boolean value = arrlist1.equals(arrlist2);
  
            // print the value
            System.out.println("Are both list equal:"
                               + value);
        }
  
        catch (NullPointerException e) {
            System.out.println("Exception thrown:" + e);
        }
    }
}

输出：

First ArrayListlist:[A, B, C, D, E]
Second ArrayList:[A, B, C, D, E]
Are both list equal:true

范例2：


// Java program to demonstrate
// equals() method
// for Integer value
  
import java.util.*;
  
public class GFG1 {
    public static void main(String[] argv)
        throws Exception
    {
  
        try {
  
            // Creating object of AbstractList<Integer>
            AbstractList<Integer>
                arrlist1 = new ArrayList<Integer>();
  
            // Populating arrlist1
            arrlist1.add(10);
            arrlist1.add(20);
            arrlist1.add(30);
            arrlist1.add(40);
            arrlist1.add(50);
  
            // print arrlist1
            System.out.println("First ArrayListlist:"
                               + arrlist1);
  
            // Creating another object of AbstractList<Integer>
            AbstractList<Integer>
                arrlist2 = new ArrayList<Integer>();
  
            // Populating arrlist2
            arrlist2.add(10);
            arrlist2.add(20);
            arrlist2.add(30);
  
            // print arrlist2
            System.out.println("Second ArrayList:"
                               + arrlist2);
  
            // comparing first ArrayList to another
            // using equals() method
            boolean value = arrlist1.equals(arrlist2);
  
            // print the value
            System.out.println("Are both list equal:"
                               + value);
        }
  
        catch (NullPointerException e) {
            System.out.println("Exception thrown:" + e);
        }
    }
}

输出：

First ArrayListlist:[10, 20, 30, 40, 50]
Second ArrayList:[10, 20, 30]
Are both list equal:false

相关用法

注：本文由纯净天空筛选整理自RohitPrasad3大神的英文原创作品 AbstractList equals() method in Java with Examples。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。