Simplest way of reading plain text from external file using Scanner.class. Remember to include this permission in your manifest file: READ_EXTERNAL_STORAGE but if you got write permission, it is not necessary to include read permission as it is already incorporated in write permission.

ReadingPlainTextUsingScanner.txt

public String readText(File file){
StringBuilder builder = new StringBuilder();
try{
Scanner scanner = new Scanner(file);
while(scanner.hasNext()){
builder.append(scanner.nextLine());
builder.append('\n');
}
scanner.close();
}
return builder.toString().trim();
}