LinkedHashSet 包含 Java 中的()方法，示例
原文:https://www . geeksforgeeks . org/link edhashset-contains-method-in-Java-with-examples/
在 Java 中，LinkedHashSet 类包含称为 contains() 的方法，如果该集合包含指定的元素，则该方法返回 true，否则返回 false。
语法:
public boolean contains(Object o)
参数:元素 o 作为参数，其在该集合中的存在性将被测试。
返回类型:一个布尔值， true 如果这个集合包含指定的元素。
例 1:
Java 语言(一种计算机语言，尤用于创建网站)
// Java program to Illustrate contains() Method
// of LinkedHashSet class
// For String value
// Importing required classes
import java.util.*;
// Main class
public class GFG {
// Main driver method
public static void main(String[] argv) throws Exception
{
// Try block to check for exceptions
try {
// Creating an empty LinkedHashSet
// Declaring object of string type
LinkedHashSet<String> linkset
= new LinkedHashSet<String>();
// Populating above HashSet
linkset.add("A");
linkset.add("B");
linkset.add("C");
// Printing all elements of above LinkedHashSet
System.out.println("LinkedHashSet: " + linkset);
// Checking the existence of element
// using contains() method
boolean exist = linkset.contains("C");
// Printing boolean value if present or not
System.out.println("Is the element"
+ " 'C' present: " + exist);
}
// Catch block to check for exceptions
catch (NullPointerException e) {
// Display message if exception occurs
System.out.println("Exception thrown : " + e);
}
}
}
Output:
LinkedHashSet: [A, B, C]
Is the element 'C' present: true
例 2:
Java 语言(一种计算机语言，尤用于创建网站)
// Java program to Illustrate contains() Method
// of LinkedHashSet class
// For Integer value
// Importing required classes
import java.util.*;
// Main class
public class GFG {
// Main driver method
public static void main(String[] argv) throws Exception
{
// Try block to check for exceptions
try {
// Creating an empty LinkedHashSet
// Declaring object of integer type
LinkedHashSet<Integer> linkset
= new LinkedHashSet<Integer>();
// Populating above HashSet
linkset.add(10);
linkset.add(20);
linkset.add(30);
// Printing all elements of above LinkedHashSet
System.out.println("LinkedHashSet: " + linkset);
// Checking the existence of element
// using contains() method
boolean exist = linkset.contains(25);
// Printing boolean value if present or not
System.out.println("Is the element"
+ " '25' present: " + exist);
}
// Catch block to check for exceptions
catch (NullPointerException e) {
// Display message if exception occurs
System.out.println("Exception thrown : " + e);
}
}
}
Output:
LinkedHashSet: [10, 20, 30]
Is the element '25' present: false
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