Java CopyOnWriteArrayList clear()用法及代碼示例

CopyOnWriteArrayList的clear()方法將擦除列表中的所有元素。調用函數後，列表的大小變為零。

用法:

public void clear()

參數：該函數不接受任何參數。

返回值：該函數不返回任何內容。

以下示例程序旨在說明上述函數：

示例1:

// Java Program to illustrate the CopyOnWriteArrayList 
// clear() method in Java 
import java.util.concurrent.CopyOnWriteArrayList; 
import java.util.*; 
  
public class GFG { 
    public static void main(String[] args) 
    { 
  
        // create object of CopyOnWriteArrayList 
        CopyOnWriteArrayList<Integer> ArrLis 
            = new CopyOnWriteArrayList<Integer>(); 
  
        // Add elements 
        ArrLis.add(32); 
        ArrLis.add(67); 
        ArrLis.add(98); 
        ArrLis.add(100); 
  
        // print CopyOnWriteArrayList 
        System.out.println("CopyOnWriteArrayList: " 
                                            + ArrLis); 
  
        ArrLis.clear(); 
  
        System.out.println("CopyOnWriteArrayList: " 
                                         + ArrLis); 
    } 
}

輸出：

CopyOnWriteArrayList: [32, 67, 98, 100]
CopyOnWriteArrayList: []

示例2:

// Java Program to illustrate the CopyOnWriteArrayList 
// clear() method in Java 
import java.util.concurrent.CopyOnWriteArrayList; 
import java.util.*; 
  
public class GFG { 
    public static void main(String[] args) 
    { 
  
        // create object of CopyOnWriteArrayList 
        CopyOnWriteArrayList<String> ArrLis 
            = new CopyOnWriteArrayList<String>(); 
  
        // Add elements 
        ArrLis.add("gopal"); 
        ArrLis.add("gfg"); 
        ArrLis.add("jgec"); 
        ArrLis.add("sudo"); 
  
        // print CopyOnWriteArrayList 
        System.out.println("CopyOnWriteArrayList: " 
                                          + ArrLis); 
  
        ArrLis.clear(); 
  
        System.out.println("CopyOnWriteArrayList: " 
                                         + ArrLis); 
    } 
}

輸出：

CopyOnWriteArrayList: [gopal, gfg, jgec, sudo]
CopyOnWriteArrayList: []

參考： https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/CopyOnWriteArrayList.html#clear–

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