ArrayList循环迭代 HashMap IO读写文件

//1.集合框架,ArrayList

import java.util.ArrayList;

import java.util.Iterator;

public class arrayListDemo {

public static void main(String[] args) {

ArrayList<String> list= newArrayList<String>();

list.add("nihao");

list.add("ni"+"jao");

System.out.println(list.size());

for(String temp:list){

System.out.println(temp);}

Iterator <String> it=list.iterator();

while(it.hasNext()){

System.out.println(it.next());}}}



//2HashMap 用法

import java.util.HashMap;

import java.util.Iterator;

import java.util.Map.Entry;

import java.util.Set;

public class hashMapDemo {

public static void main(String[] args) {

HashMap<String,Integer> map = new HashMap<String,Integer>();

map.put("nihao", 123);

map.put("hello", 25);

System.out.println("输出大小："+ map.size());

Set<Entry<String,Integer>> set = map.entrySet();

Iterator<Entry<String,Integer>> it =set.iterator();

while(it.hasNext()){

Entry<String ,Integer> entry = it.next();

System.out.println(entry.getKey()+entry1.getValue());}

for(Entry<String,Integer> entry1:set){

System.out.println("bianli "+set);

}}}



//3HashSet 用法

import java.util.HashSet;

import java.util.Iterator;

public class hasnSetDemo {

public static void main(String[] args) {

HashSet<String> set= new HashSet<String>();

set.add("1");

set.add("2");

System.out.println("daxiao"+set.size());

for(String temp:set){

System.out.println(temp);

}

Iterator<String> iterator = set.iterator();

while(iterator.hasNext()){

System.out.println(iterator.next());}}}



//4HashMap实例联系

//控制台输入一个英文单词，给出中文释义

public class qizhong {

public static void main(String[] args) {

HashMap<String,String> words = new HashMap<String,String>();

words.put("you", "你");

words.put("i","我");

File file = new File("java.txt");

try {

BufferedReader br = new BufferedReader(new FileReader(file));

String line = " ";

try {

while((line = br.readLine()) != null){

System.out.println( line);

}} catch (IOException e) {

e.printStackTrace();}

} catch (FileNotFoundException e) { e.printStackTrace();}

// System.out.println("输要查询的单词：");

// Scanner sc = new Scanner(System.in);

// String word = sc.nextLine();

// String zh = words.get(word);

// System.out.println("中文翻译："+zh);

Set<Entry<String,String>> set = words.entrySet();

for(Entry<String,String> entry:set){

System.out.println(entry.getKey()+entry.getValue()); }}}



// 5IO读取文件

import java.io.BufferedReader;

import java.io.File;

import java.io.FileNotFoundException;

import java.io.FileReader;

import java.io.IOException;

public class reader {

public static void main(String[] args) {

File file = new File("java.txt");

try {

BufferedReader br= new BufferedReader(new FileReader(file)); try {

String temp =" ";

while((temp =br.readLine()) != null){

System.out.println(temp);

}} catch (IOException e) {

e.printStackTrace(); }

} catch (FileNotFoundException e) {

e.printStackTrace();

}}}



//6

import java.io.File;

import java.io.FileNotFoundException;

import java.util.Scanner;

public class ScannerDemo {

public static void main(String[] args) throws FileNotFoundException {

File f = new File ("D:\\java\\workspace\\messae\\l.txt");

Scanner i = new Scanner(f);

while(i.hasNext()){

String name = i.next();

int Score = i.nextInt();

System.out.println(name +""+Score);

}

i.close();

}

}



//7向文件写内容

import java.io.FileNotFoundException;

import java.io.PrintWriter;

public class writer {

public static void main(String[] args) {

try {

//FileWriter

PrintWriter w = new PrintWriter("java.txt");

w.write("nihao");

w.write("555555");

char[] c ={'d','s','c'};

w.write(c);

System.out.println(w.append("1"));

w.close();

} catch (FileNotFoundException e) {

e.printStackTrace();

}}}



//输入。输出

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.IOException;

public class FileStreamDemo {

public static void main(String[] args) throws IOException {

FileOutputStream output = new FileOutputStream("D:\\java\\workspace\\messae\\l.txt");

for(int i = 1;i<=10;i++){

output.write(i);

output.close();

FileInputStream input = new FileInputStream("D:\\java\\workspace \\l.txt");

int value;

while((value = input.read())!= -1){

System.out.println(value+"");

}

input.close();

}}}