Java 8 | ArrayDeque removeIf()方法在 Java 中用示例
原文:https://www . geesforgeks . org/Java-8-arraydeque-removeif-method-in-Java-with-examples/
ArrayDeque 的 removeIf() 方法用于从 ArrayDeque 中移除满足给定谓词过滤器条件的所有元素,该条件作为参数传递给该方法。如果从向量中移除了某些元素,此方法将返回 true。
Java 8 有一个重要的内置功能接口,就是谓词。谓词或条件检查函数,它检查给定条件的给定输入,并返回相同的布尔结果,指示条件是否满足。
语法:
public boolean removeIf(Predicate<? super E> filter)
参数:该方法采用参数过滤器,该过滤器代表一个谓词,该谓词为要移除的元素返回 true。
返回:如果谓词返回真且某些元素被移除,则此方法返回真。
异常:如果指定的过滤器为空,该方法抛出空指针异常。
下面的程序说明了 ArrayDeque 的 removeIf()方法:
示例 1: 演示 ArrayDeque 上的 removeIf()方法,该方法包含一组 String,remove strings 以 a 开头。
// Java Program Demonstrate removeIf()
// method of ArrayDeque
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// create an ArrayDeque
// containing a list of string values
ArrayDeque<String> students = new ArrayDeque<String>();
// Add Strings to list
// each string represents student name
students.add("Aman");
students.add("Sanjeet");
students.add("Amar");
students.add("Rabi");
students.add("Shabbir");
// apply removeIf() method
// to remove names which start with A
students.removeIf(n -> (n.charAt(0) == 'A'));
System.out.println("Students name do not starts with A");
// print list
for (String str : students) {
System.out.println(str);
}
}
}
输出:
Students name do not starts with A
Sanjeet
Rabi
Shabbir
示例 2: 演示 ArrayDeque 上的 removeIf()方法,该方法包含一组学生对象,用于移除所有分数低于 40 分的学生。
// Java Program Demonstrate removeIf()
// method of ArrayDeque
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// create an ArrayDeque
// containing a list of Student objects
ArrayDeque<student> students = new ArrayDeque<student>();
// Add student object to list
students.add(new student("Aman", 78));
students.add(new student("Amar", 79));
students.add(new student("Suraj", 38));
students.add(new student("Raju", 22));
students.add(new student("Ankit", 76));
students.add(new student("Sanju", 62));
// apply removeIf() method
// to remove students who scores below 40
students.removeIf(n -> (n.marks <= 40));
System.out.println("Students list who score above 40");
// print list
for (student str : students) {
System.out.println(str.name + ", " + str.marks);
}
}
}
// create student class
class student {
public String name;
public int marks;
student(String name, int marks)
{
this.name = name;
this.marks = marks;
}
}
输出:
Students list who score above 40
Aman, 78
Amar, 79
Ankit, 76
Sanju, 62
示例 3: 演示 removeIf()方法中的 NullpointerException。
// Java Program Demonstrate removeIf()
// method of ArrayDeque
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// create an ArrayDeque
// containing a list of string values
ArrayDeque<String> students = new ArrayDeque<String>();
// Add Strings to list
// each string represents student name
students.add("Aman");
students.add("Sanjeet");
students.add("Amar");
students.add("Rabi");
students.add("Shabbir");
try {
// apply removeIf() method with null filter
students.removeIf(null);
}
catch (Exception e) {
System.out.println("Exception: " + e);
}
}
}
输出:
Exception: java.lang.NullPointerException
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