1.把生成的随机数写入到文件中
1 public static void WriterFun(){
2 //获得路径
3 String filepath = System.getProperty("user.dir");
4 filepath += "\\file.txt";
5
6 File file = new File(filepath);
7 if(!file.exists()){
8 try {
9 file.createNewFile();
10 } catch (IOException e) {
11 e.printStackTrace();
12 }
13 }
14 try {
15 BufferedWriter bw = new BufferedWriter(new FileWriter(file));
16
17 Random random = new Random();
18 for(int i=0;i<10000;i++){
19 int nums = Math.round(random.nextFloat()*1000.0f);
20 //将int 转化为 String类型
21 bw.write(Integer.toString(nums));
22 bw.newLine();
23 }
24 bw.close();
25
26 } catch (IOException e) {
27 e.printStackTrace();
28 }
29 }
读取文本数据
1 public static void fun1Reader(){
2
3 String filepath = System.getProperty("user.dir");
4 filepath += "\\123.txt";
5
6 File file = new File(filepath);
7 BufferedReader br;
8 try {
9 br = new BufferedReader(new FileReader(file));
10
11 String tmp;
12 while((tmp = br.readLine()) != null){
13 System.out.println(tmp);
14 }
15 } catch (Exception e) {
16 // TODO Auto-generated catch block
17 e.printStackTrace();
18 }
19 }
贴出全部代码
1.生成10000整形的随机数存入文本file.txt中
2.从file.txt中读取数据并且放入Arraylist中
3.排序 选择排序方法进行排序
4.写入到files.txt文件中
1 package com.SortDao;
2
3 import java.io.BufferedReader;
4 import java.io.BufferedWriter;
5 import java.io.File;
6 import java.io.FileNotFoundException;
7 import java.io.FileReader;
8 import java.io.FileWriter;
9 import java.io.IOException;
10 import java.util.ArrayList;
11 import java.util.Random;
12
13
14 public class WriteAndReader {
15
16
17 public static void main(String[] args) {
18 // TODO Auto-generated method stub
19 WriterFun();
20
21 // 关于为什么是Integer 不是int 大家自己网上查找一下
22 ArrayList<Integer> arrayList = ReaderFun();
23 sorts(arrayList);
24 WriterFunc(arrayList);
25 arrayList.clear();
26 }
27
28 //直接写入生成的随机数
29 public static void WriterFun(){
30 //获得路径
31 String filepath = System.getProperty("user.dir");
32 filepath += "\\file.txt";
33
34 File file = new File(filepath);
35 if(!file.exists()){
36 try {
37 file.createNewFile();
38 } catch (IOException e) {
39 e.printStackTrace();
40 }
41 }
42 try {
43 BufferedWriter bw = new BufferedWriter(new FileWriter(file));
44
45 Random random = new Random();
46 for(int i=0;i<10000;i++){
47 int nums = Math.round(random.nextFloat()*10000.0f);
48 //将int 转化为 String类型
49 bw.write(Integer.toString(nums));
50 bw.newLine();
51 }
52 bw.close();
53
54 } catch (IOException e) {
55 e.printStackTrace();
56 }
57 }
58
59 // 读入写入file.txt中的随机数
60 public static ArrayList<Integer> ReaderFun(){
61 String filepath = System.getProperty("user.dir");
62 filepath += "\\file.txt";
63 File file = new File(filepath);
64 ArrayList<Integer> arrayList = new ArrayList<Integer>();
65 if(file.exists()){
66 try {
67 BufferedReader br = new BufferedReader(new FileReader(file));
68 String tmp;
69 while((tmp = br.readLine()) != null){
70 arrayList.add(Integer.valueOf(tmp));
71
72 }
73 br.close();
74 } catch (Exception e) {
75 e.printStackTrace();
76 }
77
78 }else{
79 System.out.println("文件不存在");
80 }
81 return arrayList;
82 }
83
84 // 进行排序(应该是选择排序)
85 public static void sorts(ArrayList< Integer> arr){
86 for(int i = 0;i < arr.size();i++){
87 Integer min = arr.get(i);
88 int position = i;
89 for(int j=i;j<arr.size();j++){
90 if(min>arr.get(j)){
91 min=arr.get(j);
92 position = j;
93 }
94 }
95 arr.set(position, arr.get(i));
96 arr.set(i,min);
97 }
98 }
99
100
101 public static void WriterFunc(ArrayList<Integer> arr ){
102 String filepath = System.getProperty("user.dir");
103 filepath += "\\files.txt";
104 File file = new File(filepath);
105 if(!file.exists()){
106 try {
107 file.createNewFile();
108 } catch (IOException e) {
109 e.printStackTrace();
110 }
111 }
112 try {
113 BufferedWriter bw = new BufferedWriter(new FileWriter(file));
114
115 bw.write("After Sorted");
116 bw.newLine();
117
118 for(int i=0;i<arr.size();i++){
119 Integer num = arr.get(i);
120 bw.write(Integer.toString(num));
121 bw.newLine();
122 }
123
124 bw.close();
125
126 } catch (IOException e) {
127 e.printStackTrace();
128 }
129 }
130 }
时间： 2024-10-10 01:33:32