Java ArrayList正确的赋值方式
2022-05-11 11:06:32

//'main' method must be in a class 'Rextester'.
//Compiler version 1.8.0_111

import java.util.*;
import java.lang.*;
import java.util.ArrayList;
import java.util.Arrays;

class Rextester
{  
    public static void main(String args[])
    {
        System.out.println("Hello, World!");
        ArrayList<String> A = new ArrayList<String>();
        A.add("1");
        A.add("2");
        System.out.println(A);
        
        ArrayList<String> B;
        B=A;
        System.out.println(B);
        
        A.clear();
        System.out.println(B);
        
    }
}

//'main' method must be in a class 'Rextester'.
//Compiler version 1.8.0_111

import java.util.*;
import java.lang.*;
import java.util.ArrayList;
import java.util.Arrays;

class Rextester
{  
    public static void main(String args[])
    {
        System.out.println("Hello, World!");
        ArrayList<String> A = new ArrayList<String>();
        A.add("1");
        A.add("2");
        System.out.println(A);
        
        ArrayList<String> B = new ArrayList<String>();
        B.addAll(A);
        System.out.println(B);
        
        A.clear();
        System.out.println(B);
        
    }
}