//四种定义数组的方法int[] num  = new int[5];int[] num1;num1 = new int[5];int[] num2= new int[]{1,2,3};int[] num3 = {1,2,3};num1[0] = 1; 数组赋值len = num3.length;   //注意；如果数组的长度不变，这种的方式效率高
for(;i<=len;)
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for(int x:num3){     //jdk 1.5 之后 这种方式，也可以遍历数组
System.out.println(x);
}

public class Demo {public static void main(String[] args) {print(null);}public static void print(int[] num){System.out.println(num);  //num=null  如果调用了num.length 就会报错}
}

public class Demo {public static void main(String[] args) {int[] num = {1,2,3};//print(num);print2(1,2,3);  //直接传参(一串数字)}public static void print(int[] num){for(int i=0;i<num.length;i++){System.out.println(num[i]);}}//可变参数只能作为参数列表中的最后一个;可变参数作为数组使用public static void print2(int...num){for(int i=0;i<num.length;i++){System.out.println(num[i]);}}
}

import java.util.Arrays;
public class Demo {public static void main(String[] args){ChickManage chickManage = new ChickManage(5);chickManage.add(new Chick(0,8));chickManage.add(new Chick(1,2));chickManage.add(new Chick(2,7));chickManage.add(new Chick(3,4));chickManage.add(new Chick(4,9));chickManage.add(new Chick(5,3));
//      System.out.println(Arrays.toString(ChickManage.chicks));
//      chickManage.find(7);//      chickManage.update(7,22);//将第一个笼子小鸡编号改为22;
//      chickManage.find(22);chickManage.delete(9);//删除编号为7的小鸡}
}class ChickManage{static Chick[] chicks = null; //创建一个对象数组，该数组只能添加该对象private int count = 0;public ChickManage(int num){if(num>0){chicks = new Chick[num];}else{chicks = new Chick[5];}}public void add(Chick c){if(count<chicks.length){chicks[count] = c;count++;}else{chicks = Arrays.copyOf(chicks, chicks.length*3/2+1);chicks[count] = c;count++;}}public Chick find(int id){for(int i=0;i<count;i++){if(Integer.parseInt(chicks[i].getInfo())==id){System.out.println("小鸡的编号为"+chicks[i].getInfo()+",在第"+i+"个笼子");return chicks[i];}}System.out.println("小鸡编号不存在");return null;}public void update(int old_id,int new_id){Chick chick = find(old_id);chick.setInfo(new_id);}public void delete(int id){Chick chick = find(id);if(chick!=null){findall();if(chick.getid()==count-1){chicks[count-1] = null;count--;}else{for(int i=chick.getid();i<count;i++){chicks[i] = chicks[i+1];}count--;  //需要将count-- count是记录的笼子的个数，方便下次添加的时候从哪个地方添加  }findall();}}public void findall(){System.out.println(Arrays.toString(chicks));}
}
class Chick{private int id;private int bianhao;public Chick(int id,int bianhao){this.id = id;this.bianhao = bianhao;}public String getInfo(){return this.bianhao+"";}public int getid(){return this.id;}public void setInfo(int bianhao){this.bianhao = bianhao;}
}

import java.util.Arrays;
import java.util.List;public class T {public static void main(String[] args) {test();}public static void test(){Integer x[] ={1,2,3};//int x[] = {1,2,3} 不支持,不能把基本数据类型转化为列表,原因：asList接受的参数是一个泛型的变长参数,而基本数据类型是无法泛型化的//int[] intArray = {1, 2, 3, 4};//List<Integer> list = Ints.asList(intArray); 可以使用guava类库的工具方法,把基本数据类型的数组转化为其包装类型的listList<Integer> integers = Arrays.asList(x);System.out.println(integers);//asList方法返回的是数组的一个视图//视图意味着，对这个list的操作都会反映在原数组上，而且这个list是定长的，不支持add、remove等改变长度的方法。//integers.add(1) 不支持}
}

public class T {public static void main(String[] args) {String[] strlist = {"good","good","study","day","day","up"};Stream<String> stream = Stream.of(strlist); //泛型必须是应用类型,int[] a= {1,1,2}就不行，要使用Interger a = {1,1,1};List<String> list = stream.collect(Collectors.toList()); //将数组转成集合list.add("sss"); //可以使用add方法list.forEach(System.out::println);}
}