how to write in properties file without deleting old values

Question

I want to write in properties file without removing earlier written values in file. for Eg there is value in properties file

token = tokengenerated

Now when I again set new value like

token1 = tokensnew

Then the properties file should show

token = tokengenerated
token1 = tokensnew 

Answer 1

You should read file and update it through properties and streams.

below is the code snippet is help you.

public class ReadAndWriteProperties {

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

        Properties props = new Properties();
        String propertiesFileName = "config.properties";
        File f = new File(propertiesFileName);
        InputStream input = new FileInputStream(f);

        if (input != null) {
            props.load(input);
            props.setProperty("token2", "tokensnew");
            OutputStream out = new FileOutputStream(f);
            props.store(out, "save");
        }

    }

}

Answer 2

Pass true as a second argument to FileWriter to turn on "append" mode.

fout = new FileWriter("filename.txt", true);

FileWriter usage reference

Answer 3

您必须先读取文件（var1），然后将内容添加到var1，然后将var1写入文件。