重学java——增删改查基础

package com.it.tt5;

import java.security.PublicKey;
import java.util.ArrayList;

public class Student {
//	
	public static void main(String[] args) {	
		ArrayList<String> arrayList =  new ArrayList<>();
		
		//add element
		arrayList.add("hello");
		arrayList.add("world");
		arrayList.add("java");
		
		//delect direct element 删除置顶元素，返回是否删除成功
//		public boolean remove(Object o);
//		System.out.println(arrayList.remove("hello"));
		
//		System.out.print(arrayList.remove(1));删除置顶索引的元素，并且返回被删除的元素
//		console is   world[hello, java]
		
//		修改 
//		System.out.print(arrayList.set(1, "mimimi"));
		//world[hello, mimimi, java]  返回了被修改的元素并且修改、
		
//		搜索
//		System.out.print(arrayList.get(1));
//		System.out.print(arrayList.get(2));
//		System.out.print(arrayList.get(3)); 会发生越界
			
		//input console
		System.out.print(arrayList);
	}
}

如图

studen学生信息添加的例子

stdentexment；
package com.it.tt5;

import java.util.ArrayList;
import java.util.Scanner;
import java.util.jar.Attributes.Name;


public class studentexment {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		ArrayList<Studtentest> arrayList = new ArrayList< >();
		Scanner scanner = new Scanner(System.in);
		System.out.print("name：");
		String naemString=scanner.nextLine();
		System.out.println("age:");
		String naemString2=scanner.nextLine();

		Studtentest s = new Studtentest();
		
//	错误：	Name a = new Name(null);
//			Age b = new Age(null);
		//创建学生对象
		s.setName(naemString);
		s.setAge(naemString2);
		
		arrayList.add(s);
		//添加对象到集合中
		
		
		for(int i=0;i<arrayList.size();i++) {
			Studtentest s5 = arrayList.get(i);
			System.out.print(s.getName()+","+s.getAge());
			
		}
		System.out.print(s);

	}
	

}

Studentest class

package com.it.tt5;
//学生累
public class Studtentest {

	private String name;
	private String age;
	
	public Studtentest(){
	}
	public Studtentest (String name,String age) {
		this.name=name;
		this.age=age;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getAge() {
		return age;
	}
	public void setAge(String age) {
		this.age = age;
	}
	
}

systemin：

name：12

age:12

返回：12,12com.it.tt5.Studtentest@13a57a3b

可以得出 返回了数组和地址

标签：重学,java,String,arrayList,改查,System,age,public,name
来源： https://blog.csdn.net/Yang_tt/article/details/122015058