Question: I want to write an `ArrayList<String>` into a text file. 

The `ArrayList` is created with the code:

```
ArrayList arr = new ArrayList();

StringTokenizer st = new StringTokenizer(
    line, ":Mode set - Out of Service In Service");

while(st.hasMoreTokens()){
    arr.add(st.nextToken());    
}

```

Answer: 
```
import java.io.FileWriter;
...
FileWriter writer = new FileWriter("output.txt"); 
for(String str: arr) {
  writer.write(str + System.lineSeparator());
}
writer.close();

```
You might use ArrayList overloaded method `toString()`

```
String tmp=arr.toString();
PrintWriter pw=new PrintWriter(new FileOutputStream(file));
pw.println(tmp.substring(1,tmp.length()-1));

```