问题在这 OutputStream out = new FileOutputStream("Demo.txt"); FileOutputStream打开文件的方式默认是覆盖,就是一旦执行了上面这句,那么原有文件中的内容被清空 所以你在还没有p.load(in);加载Properties的时候就把文件清空了
那你觉得下面的程序会干什么?你在Demo.txt里随便写点东西再运行,你觉得它会输出文件内容? public static void main(String[] args) throws IOException { BufferedReader in = new BufferedReader(new FileReader("Demo.txt")); OutputStream out = new FileOutputStream("Demo.txt"); String line; while ((line = in.readLine()) != null) { System.out.println(line); }
in.close(); out.close(); }
那你觉得下面的程序会干什么?你在Demo.txt里随便写点东西再运行,你觉得它会输出文件内容? public static void main(String[] args) throws IOException { BufferedReader in = new BufferedReader(new FileReader("Demo.txt")); OutputStream out = new FileOutputStream("Demo.txt"); String line; while ((line = in.readLine()) != null) { System.out.println(line); }
in.close(); out.close(); }写成OutputStream out = new FileOutputStream("Demo.txt", true); 就行了,学习了。
那你觉得下面的程序会干什么?你在Demo.txt里随便写点东西再运行,你觉得它会输出文件内容? public static void main(String[] args) throws IOException { BufferedReader in = new BufferedReader(new FileReader("Demo.txt")); OutputStream out = new FileOutputStream("Demo.txt"); String line; while ((line = in.readLine()) != null) { System.out.println(line); }
in.close(); out.close(); }写成OutputStream out = new FileOutputStream("Demo.txt", true); 就行了,学习了。 纯粹添乱啊。变成appending只是让事情变得更加复杂
只要你在使用一个变量之前,申明了变量并进行了初始化赋值那就没有问题话说你这个文不对题啊。。你的问题和Properties类没什么关系。。
OutputStream out = new FileOutputStream("Demo.txt");
FileOutputStream打开文件的方式默认是覆盖,就是一旦执行了上面这句,那么原有文件中的内容被清空
所以你在还没有p.load(in);加载Properties的时候就把文件清空了
public static void main(String[] args) throws IOException {
BufferedReader in = new BufferedReader(new FileReader("Demo.txt"));
OutputStream out = new FileOutputStream("Demo.txt"); String line;
while ((line = in.readLine()) != null) {
System.out.println(line);
}
in.close();
out.close();
}
public static void main(String[] args) throws IOException {
BufferedReader in = new BufferedReader(new FileReader("Demo.txt"));
OutputStream out = new FileOutputStream("Demo.txt"); String line;
while ((line = in.readLine()) != null) {
System.out.println(line);
}
in.close();
out.close();
}写成OutputStream out = new FileOutputStream("Demo.txt", true);
就行了,学习了。
public static void main(String[] args) throws IOException {
BufferedReader in = new BufferedReader(new FileReader("Demo.txt"));
OutputStream out = new FileOutputStream("Demo.txt"); String line;
while ((line = in.readLine()) != null) {
System.out.println(line);
}
in.close();
out.close();
}写成OutputStream out = new FileOutputStream("Demo.txt", true);
就行了,学习了。
纯粹添乱啊。变成appending只是让事情变得更加复杂