【Java】数据结构-线性查找法
# 什么是算法> - ## 一、有限性
>
> - ## 二、确定性：不会产生二义性
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> - ## 三、可行性
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> - ## 四、输入
>
> - ## 五、输出
# 线性查找法
!(https://gitee.com/gylq/cloudimages/raw/master/img/image-20210624033722887.png)
# 使用泛型
> - ## 不可以是基本数据类型，只能是类对象
>
> - ### 基本数据类型：boolean,byte,char,short,int,long,float,double
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> - ## 每个基本数据类型都有对应的包装类
>
> - ### Boolean, Byte, Character, Short, Integer, Long, Float, Double
# 线性查找法Java执行结果截图
!(https://gitee.com/gylq/cloudimages/raw/master/img/image-20210624111228181.png)
# 线性查找法Java代码
## LinearSearch.java
```java
public class LinearSearch {
private LinearSearch(){}
public static <E> int search(E[] data, E target){ //泛型方法
for(int i = 0; i < data.length; i++)
if(data.equals(target)) //equals用于值相等，尽量不写==
return i;
return -1;
}
public static void main(String[] args){
Integer[] data = {24, 18, 12, 9, 16, 66, 32, 4}; //手动修改数组类型
int res1 = LinearSearch.search(data, 16);//自动转换泛型类，数组型不能
System.out.println(res1);
int res2 = LinearSearch.search(data, 666);
System.out.println(res2);
//以下代码可不需要-----------------------------
Student[] students = {new Student("Alice"),
new Student("Bob"),
new Student("Charles")};
Student bob = new Student("bOb"); //不区分大小写
int res3 = LinearSearch.search(students, bob);
System.out.println(res3);
}
}
```
## Student.java
```java
import java.util.Locale;
//以下代码可不需要-----------------------------
public class Student {
private String name;
public Student(String name){
this.name = name;
}
@Override
public boolean equals(Object student){ //student是Object的对象
if(this == student) //判断对象是否等于student
return true;
if(student == null)
return false;
if(this.getClass() != student.getClass()) //当前的类对象是否等于object这个student类对象
return false;
Student another = (Student)student; //将student转换为Student 进行覆盖
return this.name.toLowerCase().equals(another.name.toLowerCase()); //toLowerCase转小写，进行不区分大小写
}
}
```
!(https://gitee.com/gylq/cloudimages/raw/master/img/image-20210624052355565.png)
!(https://gitee.com/gylq/cloudimages/raw/master/img/image-20210624111001209.png)
# 线性查找算法运行结果截图
!(https://gitee.com/gylq/cloudimages/raw/master/img/image-20210624133647027.png)
# 线性查找法算法时间测试
## LinearSearch.java
```Java
public class LinearSearch {
private LinearSearch(){}
public static <E> int search(E[] data, E target){ //泛型方法
for(int i = 0; i < data.length; i++)
if(data.equals(target)) //equals用于值相等，尽量不写==
return i;
return -1;
}
public static void main(String[] args){
int[] dataSize = {10000000,100000000};
for(int n: dataSize) {
Integer[] data = ArrayGenerator.generateOrderedArray(n); //手动修改数组类型
long startTime = System.nanoTime();
for (int k = 0; k < 100; k++)
LinearSearch.search(data, n);//自动转换泛型类，数组型不能
long endTime = System.nanoTime();
double time = (endTime - startTime) / 1000000000.0; //单位是纳秒 浮点数加零 计算时间复杂 可以判断算法性能
System.out.println("n =" + n + ", 1000 runs :" + time + " s"); //打印出花费时间
}
// int res2 = LinearSearch.search(data, 666);
// System.out.println(res2);
Student[] students = {new Student("Alice"),
new Student("Bob"),
new Student("Charles")};
Student bob = new Student("bOb"); //不区分大小写
int res3 = LinearSearch.search(students, bob);
System.out.println(res3);
}
}
``` 有没有系统一点书籍？
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