数组拷贝

数组拷贝四种方式：

一、 没有隔离性，两个变量只想同一个数组。

public static void main（Strig[] args）{
  String[] s1 = {"0","1","2"}
  String[] s2 = s1;
  s2[0] = "你好";
  System.out.println(s1[0])  ;//你好
}

二、s2指向新的数组。

public static void main(String[] args){
  String[]  s1 = {"0","1","2"}  ;
  String[]  s2  = new String[s1.length];

  for(int i=0; i<s2.length; i++){
        s2[i] = s1[i];
  }

  s2[0] = "你好";

　System.out.println(s1[0])  ;//1

}

 三、API提供的方法。效率比方法二高

public static void main(String[] args) {

    String[] s1 = {"0","1","2"};
    String[] s2 = new String[s1.length];
        
    System.arraycopy(s1, 0, s2, 0, s1.length);
    System.out.println(Arrays.toString(s2));//[0,1,2]
}

四、Arrays的方法

public static void main(String[] args) {

    String[] s1 = {"0","1","2"};
    String[] s2 = Arrays.copyOf(s1, 3);
    System.out.println(Arrays.toString(s2));//[0,1,2]
        
}