Java数组的运用详解

目录

• 一，数组的含义：
• 二，数组的创建
  • 1，动态初始化
  • 2，静态初始化
• 三，数组遍历
• 四，Arrays.deepToString()与Arrays.toString()的区别
• 五，Java中Arrays类的常用方法
  • 1，数字排序
  • 2，字符串排序，先大写后小写
  • 3，严格按字母表顺序排序，也就是忽略大小写排序 CASE_INSENSITIVE_ORDER
  • 4，反向排序， Collections.reverseOrder()
  • 5，忽略大小写反向排序 （先忽略大小写，再反向排序）
  • 6，选择数组指定位置进行排序
• 六，数组去重
• 七，数组删除，增加元素
• 八，数组与List相互转换
• 总结

int [] arr={1,2,3,4,5};
for(int a = 0; a < arr.length; a++){
     System.out.print(arr[a]);
 }

 int [] arr={1,2,3,4,5};
 System.out.print(Arrays.toString(arr));

 int Arr[][]={{5,7,15},{8,4,11},{3,6,13}};
 for (int i = 0; i < Arr.length; i++) {
     for (int j = 0; j < Arr[i].length; j++) {
         System.out.print(Arr[i][j]+" ");
     }
 }

int b[][]={{5,7,15},{8,4,11},{3,6,13}};
System.out.println(Arrays.deepToString(b));

   int a[][]={{5,7,15},{8,4,11},{3,6,13}};
   System.out.println(Arrays.toString(a));
   int b[][]={{1,2,3},{8,4,11},{3,6,13}};
   System.out.println(Arrays.deepToString(b));

 int[] a = new int[5];//新建一个大小为5的数组
 Arrays.fill(a,4);//给所有值赋值4
 System.out.println(Arrays.toString(a));

 int[] b = new int[5];//新建一个大小为5的数组
 Arrays.fill(b, 2,4,1);//给第2位（0开始）到第4位（不包括）赋值6
 System.out.println(Arrays.toString(b));

 int[] a = new int[] { 4, 1, 3, -2, 10 };
 Arrays.sort(a);
 System.out.println(Arrays.toString(a));
 

 String[] a = new String[] { "a", "b", "C" };
 Arrays.sort(a);
 System.out.println(Arrays.toString(a));

 String[] a = new String[] { "a", "b", "C" };
 Arrays.sort(a, String.CASE_INSENSITIVE_ORDER);
 System.out.println(Arrays.toString(a));

 String[] a = new String[] { "a", "b", "C" };
 Arrays.sort(a, Collections.reverseOrder());
 System.out.println(Arrays.toString(a));
 

  String[] a = new String[] { "a", "B", "c","D" };
  Arrays.sort(a, String.CASE_INSENSITIVE_ORDER);
  Collections.reverse(Arrays.asList(a));
  System.out.println(Arrays.toString(a));
  

int[] a = {3,2,1,8,6,5,4,7};
Arrays.sort(a,0,3);//给第0位（0开始）到第3位（不包括）排序
System.out.print(Arrays.toString(a));

int[] a = {3,2,1,5,4};
System.out.println(a);//直接将数组打印输出

String str = Arrays.toString(a); // Arrays类的toString()方法能将数组中的内容全部打印出来
System.out.println(str);

int[] arr1 = {1,2,3};
int[] arr2 = {1,2,3};
System.out.println(Arrays.equals(arr1,arr2));
System.out.println(arr1.equals(arr2));

int[] a= {3, 7, 2, 1};
int[] b=Arrays.copyOf(arr6, 4);  //指定新数组的长度
int[] c=Arrays.copyOfRange(a, 1, 3); //只复制从索引[1]到索引[3]之间的元素（不包括索引[3]的元素）

System.out.println(Arrays.toString(b));
System.out.println(Arrays.toString(c));

String[] array={"aaa","bbb","ccc","ddd","eee"};
String a="aaa";
String b="fff";
if (Arrays.asList(array).contains(a)) {
    System.out.println("1");
}else {
    System.out.println("2");
}

if (Arrays.asList(array).contains(b)) {
    System.out.println("1");
}else {
    System.out.println("2");
}

int[] arr11 = {1,2,3,4,5,6,7,8,9,0,3,2,4,5,6,7,4,32,2,1,1,4,6,3};
Set<Integer> set2=new HashSet<Integer>();
for (int i = 0; i < arr11.length; i++) {
    set2.add(arr11[i]);
}
System.out.println(set2);
int[] arr12 = new int[set2.size()];
int j=0;
for (Integer i:set2) {
    arr12[j++]=i;
}
System.out.println(Arrays.toString(arr12));

int[] str = {5, 6, 6, 6, 8, 8, 7,4};
List<Integer> list = new ArrayList<Integer>();
for (int i=0; i<str.length; i++) {
    if(!list.contains(str[i])) {
        list.add(str[i]);
    }
}
System.out.println("去除重复后的list集合"+list);

Integer[] nums = { 5, 5, 6, 6, 6, 8, 8, 7, 11, 12, 12 };
HashSet hset = new HashSet(Arrays.asList(nums));
//TreeSet<Integer> hset = new TreeSet<Integer>(Arrays.asList(nums));
Iterator i = hset.iterator();
while(i.hasNext()){
 	System.out.print(i.next());
}

int[] nums = { 5, 6, 6, 6, 8, 8, 7 };
List<Integer> numList = new ArrayList<Integer>();
for (int i : nums)
    numList.add(i);
Set<Integer> numSet = new HashSet<Integer>();
numSet.addAll(numList);
System.out.println(numSet);

String [] str = {"Java", "C++", "Php", "C#", "Python"};//删除php
List<String> list = new ArrayList<String>();
for (int i=0; i<str.length; i++) {
    list.add(str[i]);
}
list.remove(2); //list.remove("Php")
String[] newStr =  list.toArray(new String[1]); //返回一个包含所有对象的指定类型的数组
System.out.println(Arrays.toString(newStr));

String [] str = {"Java", "C++", "Php", "C#", "Python"};//增加ruby
List<String> list = new ArrayList<String>();
for (int i=0; i<str.length; i++) {
    list.add(str[i]);
}
list.add(2, "ruby");
String[] newStr =  list.toArray(new String[1]); //返回一个包含所有对象的指定类型的数组
System.out.println(Arrays.toString(newStr));

String[] strs = new String[] {"aaa", "bbb", "ccc"};
List<String> list = Arrays.asList(strs);
for (String s : list) {
    System.out.println(s);
}

List<String> list2 = Arrays.asList("aaa", "bbb", "ccc");
String[] array = list2.toArray(new String[list2.size()]);
for (String s : array) {
    System.out.println(s);
}