Collection (properties)

aggregate （Properties）

The reason for introducing this collection is that it can be used in conjunction with streams .
The specific description of this set is not described in detail in this article , The details will be added in the previous collection article . Give a brief explanation and its usage .

This set starts with Map Subclass under , So it's also a double column set . However, generics are not supported . Use the code to see the specific use . Simple demonstration .

package io_demo;import java.util.Properties;import java.util.Set;public class IoDemo_25 {    public static void main(String[] args) {        // Create a collection object         Properties pro = new Properties();        // Storage elements         pro.put(001,"jgdabc");        pro.put(002," Blue boat and thousand sails ");        pro.put(002,"lym");        // Ergodic set         Set<Object> KeySet = pro.keySet();        for(Object key:KeySet)        {            Object value = pro.get(key);            System.out.print(key+","+value);        }        pro.setProperty("000","jgdabc");        pro.getProperty("000");        // Get key value         Set<String> names = pro.stringPropertyNames();// Get key set         // So you can traverse         for(String key:names)        {            String value = pro.getProperty(key);            System.out.println(key+value);        }    }}

== its put（） The method key is Object Type of ,setProperty() The key of the method must be String type .== This needs attention .

Assemble to file , File to collection

package io_demo;import java.io.FileNotFoundException;import java.io.FileReader;import java.io.FileWriter;import java.io.IOException;import java.util.Properties;public class IoDemo_26 {    public static void main(String[] args) throws IOException {        // Save the data in the collection to a file         myStore();        // Load file data into collection         myLoad();    }    private static void myLoad() throws IOException {        Properties prop = new Properties();        FileReader fr = new FileReader("E:\\java_doc\\src\\io_demo\\jgdabc.txt");        prop.load(fr);        fr.close();        System.out.print(prop);    }    private static void myStore() throws IOException {        Properties prop = new Properties();        prop.setProperty("000","jack");        prop.setProperty("001","jgdabc");        prop.setProperty("002","john");        FileWriter fw = new FileWriter("E:\\java_doc\\src\\io_demo\\jgdabc.txt");        prop.store(fw,null);//null Does not represent descriptive information     }}

Play a number guessing game

Give a in the file count=0, Then use this set to read the data （ Need to be converted to int type , Then limit according to the value , Limit the number of times you play . Of course not, every time it runs, it will count+1, Run three times and you can't play . This is different from interacting all the time .）
First, a number guessing game

package java_practice;import java.util.Scanner;public  class GuessNumber {    public static  void start()    {        Scanner input = new Scanner(System.in);        int number = (int) (Math.random() * 100)+1; //  Generate random numbers         int guess;//  The number the user guessed         int count = 0;//  Number of guesses         System.out.println(" I have a in my heart 0 To 100 Integer between , Guess what ？");        //  Users guess random numbers         do {            guess = input.nextInt();            if (number < guess) {                System.out.println(" It's a little big , Guess again ！");                count++;            } else if (number > guess) {                System.out.println(" It's a little smaller , Guess again ！");                count++;            } else {                count++;                break;            }        } while (true);        System.out.println(" The number is "+number);        System.out.println(" The number of times you guess is "+count);        //  Give an evaluation according to the number of guesses         if (count == 1) {            System.out.println(" You are too smart ！");        } else if (count >= 2 && count <= 5) {            System.out.println(" Pretty good , Make persistent efforts ！");        } else {            System.out.println(" Work hard ！");        }    }}

Then a test main class

package io_demo;import java_practice.GuessNumber;import java.io.FileNotFoundException;import java.io.FileReader;import java.io.FileWriter;import java.io.IOException;import java.sql.SQLOutput;import java.util.Properties;public class IoDemo_27 {    public static void main(String args[]) throws IOException {        GuessNumber guessNumber = new GuessNumber();        Properties prop = new Properties();        FileReader fr = new FileReader("E:\\java_doc\\src\\io_demo\\count.txt");        prop.load(fr);        fr.close();        String count = prop.getProperty("count");        int number = Integer.parseInt(count);        if(number>=3)        {            System.out.println(" The game trial is over , If you want to play, please recharge ");        }else        {           guessNumber.start();            prop.setProperty("count",String.valueOf(number));            number++;            FileWriter fw =  new FileWriter("E:\\java_doc\\src\\io_demo\\count.txt");            prop.store(fw,null);            fw.close();        }    }}

Be sure to create a file yourself , There is a tag value in it . In this way, the function can be realized .