- 学生类
public class Student {
// 姓名
private String name;
// 语文成绩
private int chinese;
// 数学成绩
private int math;
// 英语成绩
private int english;
public Student() {
super();
}
public Student(String name, int chinese, int math, int english) {
super();
this.name = name;
this.chinese = chinese;
this.math = math;
this.english = english;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getChinese() {
return chinese;
}
public void setChinese(int chinese) {
this.chinese = chinese;
}
public int getMath() {
return math;
}
public void setMath(int math) {
this.math = math;
}
public int getEnglish() {
return english;
}
public void setEnglish(int english) {
this.english = english;
}
public int getSum() {
return this.chinese + this.math + this.english;
}
}
- 测试类
public class TreeSetToFileDemo {
public static void main(String[] args) throws IOException {
//创建TreeSet集合，通过比较器排序进行排序
TreeSet<Student> ts = new TreeSet<Student>(new Comparator<Student>() {
@Override
public int compare(Student s1, Student s2) {
//成绩总分从高到低
int num = s2.getSum() - s1.getSum();
//次要条件
int num2 = num == 0 ? s1.getChinese() - s2.getChinese() : num;
int num3 = num2 == 0 ? s1.getMath() - s2.getMath() : num2;
int num4 = num3 == 0 ? s1.getName().compareTo(s2.getName()) : num3;
return num4;
}
});
//键盘录入学生数据
for (int i = 0; i < 5; i++) {
Scanner sc = new Scanner(System.in);
System.out.println("请录入第" + (i + 1) + "个学生信息：");
System.out.println("姓名：");
String name = sc.nextLine();
System.out.println("语文成绩：");
int chinese = sc.nextInt();
System.out.println("数学成绩：");
int math = sc.nextInt();
System.out.println("英语成绩：");
int english = sc.nextInt();
//创建学生对象，把键盘录入的数据对应赋值给学生对象的成员变量
Student s = new Student();
s.setName(name);
s.setChinese(chinese);
s.setMath(math);
s.setEnglish(english);
//把学生对象添加到TreeSet集合
ts.add(s);
}
//创建字符缓冲输出流对象
BufferedWriter bw = new BufferedWriter(new FileWriter("myCharStream\\ts.txt"));
//遍历集合，得到每一个学生对象
for (Student s : ts) {
//把学生对象的数据拼接成指定格式的字符串
//格式：姓名,语文成绩,数学成绩,英语成绩
StringBuilder sb = new StringBuilder();
sb.append(s.getName()).append(",").append(s.getChinese()).append(",").append(s.getMath()).append(",").append(s.getEnglish()).append(",").append(s.getSum());
public class CopyFolderDemo {
public static void main(String[] args) throws IOException {
//创建数据源目录File对象，路径是E:\\itcast
File srcFolder = new File("E:\\itcast");
public class CopyFoldersDemo {
public static void main(String[] args) throws IOException {
//创建数据源File对象，路径是E:\\itcast
File srcFile = new File("E:\\itcast");
//创建目的地File对象，路径是F:\\
File destFile = new File("F:\\");
//抛出处理
private static void method1() throws IOException {
FileReader fr = new FileReader("fr.txt");
FileWriter fw = new FileWriter("fw.txt");
char[] chs = new char[1024];
int len;
while ((len = fr.read()) != -1) {
fw.write(chs, 0, len);
}
fw.close();
fr.close();
}
}
1.4.2JDK7版本改进
public class CopyFileDemo {
public static void main(String[] args) {
}
//JDK7的改进方案
private static void method3() {
try(FileReader fr = new FileReader("fr.txt");
FileWriter fw = new FileWriter("fw.txt");){
char[] chs = new char[1024];
int len;
while ((len = fr.read()) != -1) {
fw.write(chs, 0, len);
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
1.4.3JDK9版本改进
public class CopyFileDemo {
public static void main(String[] args) {
}
//JDK9的改进方案
private static void method4() throws IOException {
FileReader fr = new FileReader("fr.txt");
FileWriter fw = new FileWriter("fw.txt");
try(fr;fw){
char[] chs = new char[1024];
int len;
while ((len = fr.read()) != -1) {
fw.write(chs, 0, len);
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
2.IO特殊操作流
2.1标准输入流【应用】
- System类中有两个静态的成员变量
- public static final InputStream in：标准输入流。通常该流对应于键盘输入或由主机环境或用户指定的另一个输入源
- public static final PrintStream out：标准输出流。通常该流对应于显示输出或由主机环境或用户指定的另一个输出目标
- 自己实现键盘录入数据
public class SystemInDemo {
public static void main(String[] args) throws IOException {
//public static final InputStream in：标准输入流
// InputStream is = System.in;
// int by;
// while ((by=is.read())!=-1) {
// System.out.print((char)by);
// }
//如何把字节流转换为字符流？用转换流
// InputStreamReader isr = new InputStreamReader(is);
// //使用字符流能不能够实现一次读取一行数据呢？可以
// //但是，一次读取一行数据的方法是字符缓冲输入流的特有方法
// BufferedReader br = new BufferedReader(isr);
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
System.out.println("请输入一个字符串：");
String line = br.readLine();
System.out.println("你输入的字符串是：" + line);
System.out.println("请输入一个整数：");
int i = Integer.parseInt(br.readLine());
System.out.println("你输入的整数是：" + i);
//自己实现键盘录入数据太麻烦了，所以Java就提供了一个类供我们使用
Scanner sc = new Scanner(System.in);
}
}
2.2标准输出流【应用】
- System类中有两个静态的成员变量
- public static final InputStream in：标准输入流。通常该流对应于键盘输入或由主机环境或用户指定的另一个输入源
- public static final PrintStream out：标准输出流。通常该流对应于显示输出或由主机环境或用户指定的另一个输出目标
- 输出语句的本质：是一个标准的输出流
- PrintStream ps = System.out;
- PrintStream类有的方法，System.out都可以使用
- 示例代码
public class SystemOutDemo {
public static void main(String[] args) {
//public static final PrintStream out：标准输出流
PrintStream ps = System.out;