
- Java.util 包类
- Java.util - 首页
- Java.util - ArrayDeque
- Java.util - ArrayList
- Java.util - Arrays
- Java.util - BitSet
- Java.util - Calendar
- Java.util - Collections
- Java.util - Currency
- Java.util - Date
- Java.util - Dictionary
- Java.util - EnumMap
- Java.util - EnumSet
- Java.util - Formatter
- Java.util - GregorianCalendar
- Java.util - HashMap
- Java.util - HashSet
- Java.util - Hashtable
- Java.util - IdentityHashMap
- Java.util - LinkedHashMap
- Java.util - LinkedHashSet
- Java.util - LinkedList
- Java.util - ListResourceBundle
- Java.util - Locale
- Java.util - Observable
- Java.util - PriorityQueue
- Java.util - Properties
- Java.util - PropertyPermission
- Java.util - PropertyResourceBundle
- Java.util - Random
- Java.util - ResourceBundle
- Java.util - ResourceBundle.Control
- Java.util - Scanner
- Java.util - ServiceLoader
- Java.util - SimpleTimeZone
- Java.util - Stack
- Java.util - StringTokenizer
- Java.util - Timer
- Java.util - TimerTask
- Java.util - TimeZone
- Java.util - TreeMap
- Java.util - TreeSet
- Java.util - UUID
- Java.util - Vector
- Java.util - WeakHashMap
- Java.util 包其他内容
- Java.util - 接口
- Java.util - 异常
- Java.util - 枚举
- Java.util 有用资源
- Java.util - 有用资源
- Java.util - 讨论
Java Vector contains() 方法
描述
Java Vector contains(Object elem) 方法用于测试向量中是否存在某个元素。
声明
以下是 java.util.Vector.contains() 方法的声明
public boolean contains(Object elem)
参数
elem − 这是作为输入的对象。
返回值
true − 当且仅当指定对象与此向量中的某个组件相同时,返回 true。否则返回 false。
异常
ClassCastException − 如果指定元素的类型与此集合不兼容(可选)。
NullPointerException − 如果指定元素为 null,并且此集合不支持 null 元素(可选)。
检查整数向量中元素是否存在示例
以下示例演示了 Java Vector contains() 方法的使用。我们使用的是 Integer。我们将添加一些元素,然后检查是否存在某个元素。
package com.tutorialspoint; import java.util.Vector; public class VectorDemo { public static void main(String[] args) { // create an empty vector Vector<Integer> vector = new Vector<>(); // use add() method to add elements in the vector vector.add(20); vector.add(30); vector.add(10); vector.add(18); // let us print all the elements available in vector System.out.println("Vector = " + vector); // vector contains element 10 if (vector.contains(10)) { System.out.println("element 10 is present in the vector"); } else { System.out.println("element 10 is not present in the vector"); } // vector does not contain element 25 if (vector.contains(25)) { System.out.println("element 25 is present in the vector"); } else { System.out.println("element 25 is not present in the vector"); } } }
输出
让我们编译并运行上述程序,这将产生以下结果:
Vector = [20, 30, 10, 18] element 10 is present in the vector element 25 is not present in the vector
检查字符串向量中元素是否存在示例
以下示例演示了 Java Vector contains() 方法与字符串一起使用的情况。我们将添加一些元素,然后检查是否存在某个元素。
package com.tutorialspoint; import java.util.Vector; public class VectorDemo { public static void main(String[] args) { // create an empty vector Vector<String> vector = new Vector<>(); // use add() method to add elements in the vector vector.add("Welcome"); vector.add("to"); vector.add("tutorialspoint"); vector.add(".com"); // let us print all the elements available in vector System.out.println("Vector = " + vector); // vector contains element tutorialspoint if (vector.contains("tutorialspoint")) { System.out.println("element tutorialspoint is present in the vector"); } else { System.out.println("element tutorialspoint is not present in the vector"); } // vector does not contain element html if (vector.contains("html")) { System.out.println("element html is present in the vector"); } else { System.out.println("element html is not present in the vector"); } } }
输出
让我们编译并运行上述程序,这将产生以下结果:
Vector = [Welcome, to, tutorialspoint, .com] element tutorialspoint is present in the vector element html is not present in the vector
检查对象向量中元素是否存在示例
以下示例演示了 Java Vector contains() 方法与 Student 对象一起使用的情况。我们将添加一些元素,然后检查是否存在某个元素。
package com.tutorialspoint; import java.util.Vector; public class VectorDemo { public static void main(String[] args) { // create an empty vector Vector<Student> vector = new Vector<>(); // use add() method to add elements in the vector vector.add(new Student(1, "Julie")); vector.add(new Student(2, "Robert")); vector.add(new Student(3, "Adam")); // let us print all the elements available in vector System.out.println("Vector = " + vector); // vector contains element Robert if (vector.contains(new Student(2, "Robert"))) { System.out.println("Student Robert is present in the vector"); } else { System.out.println("Student Robert is not present in the vector"); } // vector does not contain element Jane if (vector.contains(new Student(4, "Jane"))) { System.out.println("Student Jane is present in the vector"); } else { System.out.println("Student Jane is not present in the vector"); } } } class Student { int rollNo; String name; Student(int rollNo, String name){ this.rollNo = rollNo; this.name = name; } @Override public String toString() { return "[ " + this.rollNo + ", " + this.name + " ]"; } @Override public boolean equals(Object obj) { Student s = (Student)obj; return this.rollNo == s.rollNo && this.name.equalsIgnoreCase(s.name); } }
输出
让我们编译并运行上述程序,这将产生以下结果:
Vector = [[ 1, Julie ], [ 2, Robert ], [ 3, Adam ]] Student Robert is present in the vector Student Jane is not present in the vector
java_util_vector.htm
广告