if you only want the whole text in one string than you can use the FileInputStream
FileInputStream inputStream = new FileInputStream("foo.txt");
try {
    String everything = IOUtils.toString(inputStream);
} finally {
    inputStream.close();
}
if you want to read the file line bye line use the BufferdReader in Connection with StringBuilder
BufferedReader br = new BufferedReader(new FileReader("file.txt"));
try {
    StringBuilder sb = new StringBuilder();
    String line = br.readLine();
while (line != null) {
    sb.append(line);
    sb.append(System.lineSeparator());
    line = br.readLine();
}
String everything = sb.toString();
}finally {
    br.close();
}
Note: 
The examples are taken from @Knubo and the whole answer and further Information can be found 
here