Arrays(java)

package com.arrays;import java.util.Arrays;public class Test {    public static void main(String[] args) { int [] arr={11,22,44,88,66,33,55,77}; //返回地址 System.out.println(arr);  //[I@1b6d3586 //返回数组的内容 System.out.println(Arrays.toString(arr));  //[11, 22, 44, 88, 66, 33, 55, 77] //排序。升序 Arrays.sort(arr); System.out.println(Arrays.toString(arr)); //[11, 22, 33, 44, 55, 66, 77, 88] //二分搜索技术，前提要排好序 int i = Arrays.binarySearch(arr, 00); System.out.println(i);  //-1 int i1 = Arrays.binarySearch(arr, 50); System.out.println(i1);  //-5  表示：-（应该插入的位置的索引+1）    }}

package com.arrays;import java.util.Arrays;import java.util.Comparator;//comparator比较器对象public class Test1 {    public static void main(String[] args) { int [] arr={12,56,32,23,78,19}; //Array的sort方法默认升序排序 Arrays.sort(arr); System.out.println(Arrays.toString(arr));  //[12, 19, 23, 32, 56, 78] Integer [] arr1={12,56,32,23,78,19}; Arrays.sort(arr1, new Comparator<Integer>() {     @Override     public int compare(Integer o1, Integer o2) {  //指定规则  /*if (o1>o2){      return 1;  }  else if (o1<o2){      return -1;  }  return 0;*/  //return o1-o2;  //默认升序    // //[12, 19, 23, 32, 56, 78]  return o2-o1;   //降序  //[78, 56, 32, 23, 19, 12]     } }); System.out.println(Arrays.toString(arr1));    }}

package com.arrays;public class Student {    String name;    int age;    double height;    public Student() {    }    public Student(String name, int age, double height) { this.name = name; this.age = age; this.height = height;    }    public String getName() { return name;    }    public void setName(String name) { this.name = name;    }    public int getAge() { return age;    }    public void setAge(int age) { this.age = age;    }    public double getHeight() { return height;    }    public void setHeight(double height) { this.height = height;    }    @Override    public String toString() { return "Student{" +  "name='" + name + '\'' +  ", age=" + age +  ", height=" + height +  '}';    }}package com.arrays;import java.util.Arrays;import java.util.Comparator;public class StudentTest {    public static void main(String[] args) { Student[] students=new Student[4]; students[0]=new Student("小马哥",23,180.5); students[1]=new Student("小飞侠",32,183.5); students[2]=new Student("马奎斯",40,170.5); students[3]=new Student("罗西",20,190.5); Arrays.sort(students, new Comparator<Student>() {     @Override     public int compare(Student o1, Student o2) {  //制定排序规则  //按照年龄升序  //return o1.getAge()-o2.getAge();  //[Student{name='罗西', age=20, height=190.5}, Student{name='小马哥', age=23, height=180.5}, Student{name='小飞侠', age=32, height=183.5}, Student{name='马奎斯', age=40, height=170.5}]  //按照年龄降序  //return o2.getAge()-o1.getAge();  //[Student{name='马奎斯', age=40, height=170.5}, Student{name='小飞侠', age=32, height=183.5}, Student{name='小马哥', age=23, height=180.5}, Student{name='罗西', age=20, height=190.5}]  //按照身高升序排序  //return Double.compare(o1.getHeight(),o2.getHeight()); //[Student{name='马奎斯', age=40, height=170.5}, Student{name='小马哥', age=23, height=180.5}, Student{name='小飞侠', age=32, height=183.5}, Student{name='罗西', age=20, height=190.5}]  //按照身高降序  return Double.compare(o2.getHeight(),o1.getHeight());  //[Student{name='罗西', age=20, height=190.5}, Student{name='小飞侠', age=32, height=183.5}, Student{name='小马哥', age=23, height=180.5}, Student{name='马奎斯', age=40, height=170.5}]     } }); System.out.print(Arrays.toString(students));    }}

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