Demo1(Read the second line)
finally和try里如果同时抛出异常,try里面的异常不会显示在异常堆栈里,会影响debug。
static void readFirstLineOfFile(String path) throws IOException {
BufferedReader bufferedReader
= new BufferedReader(new FileReader(path));
try{
bufferedReader.readLine();
System.out.println(bufferedReader.readLine());
}finally {
bufferedReader.close();
}
}
Demo2(Copy)
需要关闭的资源多了,用try-with有点傻
static void copy(String src, String dst) throws IOException {
FileInputStream in = new FileInputStream(src);
try{
FileOutputStream out = new FileOutputStream(dst);
try{
byte[] b = new byte[100];
int n = 0;
while( 0<=(n = in.read(b))){
out.write(b, 0, n);
}
}finally{
out.close();
}
}finally {
in.close();
}
}
Demo3(New-Read the second line)
使用try-resources会自动执行close方法,这样可读性更高。AutoCloseable接口需要被实现。
static void readFirstLineOfFileNew(String path) throws IOException {
try(BufferedReader bufferedReader
= new BufferedReader(new FileReader(path))){
bufferedReader.readLine();
System.out.println(bufferedReader.readLine());
}
}
Demo4
使用了try-with-resources
static void copy2(String src, String dst) throws IOException {
try(FileInputStream in = new FileInputStream(src);
FileOutputStream out = new FileOutputStream(dst);
) {
byte[] b = new byte[100];
int n = 0;
while( 0<=(n = in.read(b))){
out.write(b, 0, n);
}
}
}
test unit
public static void main(String[] args) throws IOException {
// Item9.readFirstLineOfFile("c:/work/a.txt");
// Item9.copy("c:/work/a.txt", "c:/work/b.txt");
// Item9.readFirstLineOfFileNew("c:/work/a.txt");
Item9.copy2("c:/work/a.txt", "c:/work/c1.txt");
}