Java基础知识

Posted 2021-12-16 wujianbo123

一 Java基础知识

 

1.01 数组

 

package com.test.testfan;

public class testfan_01_01_数组 

    /**
     * @param args
     */
    public static void main(String[] args) 
        // TODO 自动生成的方法存根
        
        int[] a = new int[]33, 33,3, 44;
        System.out.println(a[0]);
        System.out.println(a.length);
        System.out.println(a[a.length-1]);//获取最后位数据
        
        /*for (int i = 0; i < a.length; i++) 
            int j = a[i];
            System.out.println(j);
        */
        
        
        int[] b = new int[100];
        b[0] = 1;
        b[1] = 1;
        b[2] = 1;
        b[3] = 1;
        b[4] = 1;
        System.out.println(b.length);
        

    

 

 

1.02 集合

package com.test.testfan;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

public class testfan_01_02_集合 

	public static void main(String[] args) 
		// TODO 自动生成的方法存根
		List<String> list = new ArrayList<String>();
		list.add("200");
		String valueString = list.get(0);
		System.out.println(valueString);
		System.out.println(list.size());//类属性
		//System.out.println(list.);//类属性
		
		//通过数组
		for (int i = 0; i < args.length; i++) 
			String string = args[i];
			
		
		

		List<Integer> list2 = new ArrayList<Integer>();
		list2.add(200);
		int value2 = list2.get(0);

		for (int i = 0; i < args.length; i++) 
			String string = args[i];
			System.out.println(string);

		

		//通过集合
		for (Iterator iterator = list2.iterator(); iterator.hasNext();) 
			Integer integer = (Integer) iterator.next();
			System.out.println(integer);
		
		 
		//通过数组
		for (int i = 0; i < args.length; i++) 
			
		
		//通过迭代器 
		for (Integer integer : list2) 
			System.out.println(integer);
		
		
		

	

 

package com.test.testfan;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

public class testfan_01_02_集合 

	public static void main(String[] args) 
		// TODO 自动生成的方法存根
		List<String> list = new ArrayList<String>();
		list.add("200");
		String valueString = list.get(0);
		System.out.println(valueString);
		System.out.println(list.size());//类属性
		//System.out.println(list.);//类属性
		
		//通过数组
		for (int i = 0; i < args.length; i++) 
			String string = args[i];
			
		
		

		List<Integer> list2 = new ArrayList<Integer>();
		list2.add(200);
		int value2 = list2.get(0);

		for (int i = 0; i < args.length; i++) 
			String string = args[i];
			System.out.println(string);

		

		//通过集合
		for (Iterator iterator = list2.iterator(); iterator.hasNext();) 
			Integer integer = (Integer) iterator.next();
			System.out.println(integer);
		
		 
		//通过数组
		for (int i = 0; i < args.length; i++) 
			
		
		//通过迭代器 
		for (Integer integer : list2) 
			System.out.println(integer);
		
		
		
		
		// 数组属性使用
		List<Integer> list3 = new ArrayList<Integer>();
		if(!list3.isEmpty()) 
			int list4 = list3.get(0);
			System.out.println(list4);
		

		list3.add(200);

	

　　

1.03 对象

package com.test.testfan;

public class Person 
	public String name;
	public int age;
	private double money=1000;
	public String sex;
	public double getMoney() 
		return money;
	
	public void setMoney(double money) 
		this.money = money;
	
	
	
	

package com.test.testfan;

public class testfan_01_03_对象 

	public static void main(String[] args) 
		// TODO 自动生成的方法存根
		
		Person p1 = new Person();
		Person p2 = new Person();
		
		p1.name = "zhangsan";
		p1.setMoney(60000.00);
		System.out.println(p1.name);
		System.out.println(p1.getMoney());
		System.out.println(p1);
		
		System.out.println("-------------");
		
		p2.name = "zhangsan9999";
		p2.setMoney(90000.00);
		System.out.println(p2.name);
		System.out.println(p2.getMoney());
		System.out.println(p2);