java 两个数组合并的几种方法

//方法一 Arrays类  String[] a = {"A","B","C"};  String[] b = {"D","E"};  // List<String> list = Arrays.asList(a);  --OK  // List<String> list = Arrays.asList("A","B","C"); --OK  // list.add("F"); --UnsupportedOperationException  // list.remove("A"); --UnsupportedOperationException  // list.set(1,"javaee");--OK (因为是把数组转为集合，其本质还是数组，数组长度固定不变，但内容可以改变)  // 结论：虽然可以把数组转为集合，但是集合长度不能改变  List list = new ArrayList(Arrays.asList(a));  list.addAll(Arrays.asList(b));  String[] str = new String[list.size()];  list.toArray(str);    for(int x=0;x<str.length;x++){    System.out.print(str[x] + " ");  }//方法二 循环遍历// 两个数组合并  String[] str1 = {"Hello","world","java"};  String[] str2 = {"Veriable","syntax","interator"};  String[] newStr = new String[str1.length+str2.length];  //newStr = str1;数组是引用类型  for(int x=0;x<str1.length;x++){    newStr[x] = str1[x];  }      for(int y=0;y<str2.length;y++){    newStr[str1.length+y]=str2[y];  }  for(int y=0;y<newStr.length;y++){    System.out.println(newStr[y] + " ");  }// 方法三  String[] str1 = {"Hello","world","java"};  String[] str2 = {"Veriable","syntax","interator"};  int str1Length = str1.length;  int str2length = str2.length;      str1 = Arrays.copyOf(str1, str1Length+str2length);//数组扩容  System.arraycopy(str2, 0, str1, str1Length, str2length);  System.out.println(Arrays.toString(str1));