Java by API/java.util/Scanner

new Scanner(FileReader file)

 
/**
 *Output:
String: Testing
String: Scanner
int: 10
double: 12.2
String: one
boolean: true
String: two
boolean: false
 */
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Scanner;
public class MainClass {
  public static void main(String args[]) throws IOException {
    int i;
    double d;
    boolean b;
    String str;
    FileWriter fout = new FileWriter("test.txt");
    fout.write("Testing Scanner 10 12.2 one true two false");
    fout.close();
    FileReader fin = new FileReader("Test.txt");
    Scanner src = new Scanner(fin);
    while (src.hasNext()) {
      if (src.hasNextInt()) {
        i = src.nextInt();
        System.out.println("int: " + i);
      } else if (src.hasNextDouble()) {
        d = src.nextDouble();
        System.out.println("double: " + d);
      } else if (src.hasNextBoolean()) {
        b = src.nextBoolean();
        System.out.println("boolean: " + b);
      } else {
        str = src.next();
        System.out.println("String: " + str);
      }
    }
    fin.close();
  }
}

new Scanner(InputStream source)

 
/**
 *Output:
 */
import java.util.Scanner;
public class MainClass {
  public static void main(String args[]) {
    Scanner conin = new Scanner(System.in);
    int count = 0;
    double sum = 0.0;
    System.out.println("Enter numbers to average.");
    while (conin.hasNext()) {
      if (conin.hasNextDouble()) {
        sum += conin.nextDouble();
        count++;
      } else {
        String str = conin.next();
        if (str.equals("done"))
          break;
        else {
          System.out.println("Data format error.");
          return;
        }
      }
    }
    System.out.println("Average is " + sum / count);
  }
}

new Scanner(Readable source)

 
/*
 */
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Scanner;
public class MainClass {
  public static void main(String args[]) throws IOException {
    int count = 0; 
    double sum = 0.0; 
 
    FileWriter fout = new FileWriter("test.txt"); 
 
    fout.write("2, 3.4,    5,6, 7.4, 9.1, 10.5, done"); 
    fout.close(); 
 
    FileReader fin = new FileReader("Test.txt"); 
 
    Scanner src = new Scanner(fin); 
 
    src.useDelimiter(", *"); 
 
    while(src.hasNext()) { 
      if(src.hasNextDouble()) { 
        sum += src.nextDouble(); 
        count++; 
      } 
      else { 
        String str = src.next();  
        if(str.equals("done")) break; 
        else { 
          System.out.println("File format error."); 
          return; 
        } 
      } 
    } 
 
    fin.close(); 
    System.out.println("Average is " + sum / count); 
  }
}

new Scanner(String instr)

 
/**
 *Output:
28
 */
import java.util.Scanner;
public class MainClass {
  public static void main(String args[]) {
    String instr = "Name: Joe Age: 28 ID: 77";
    Scanner conin = new Scanner(instr);
    conin.findInLine("Age:"); // find Age
    if (conin.hasNext())
      System.out.println(conin.next());
    else
      System.out.println("Error!");
  }
}

Scanner: findInLine(String str)

 
/**
 *Output:
28
 */
import java.util.Scanner;
public class MainClass {
  public static void main(String args[]) {
    String instr = "Name: Joe Age: 28 ID: 77";
    Scanner conin = new Scanner(instr);
    conin.findInLine("Age:"); // find Age
    if (conin.hasNext())
      System.out.println(conin.next());
    else
      System.out.println("Error!");
  }
}

Scanner: findWithinHorizon(String pattern, int horizon)

 
import java.util.Scanner;
public class Main {
  public static void main(String args[]) {
    Scanner sc = new Scanner("Name: Tom Age: 28 ID: 77");
    sc.findWithinHorizon("ID:",100);
    if (sc.hasNext())
      System.out.println(sc.next());
    else
      System.out.println("Error!");
  }
}

Scanner: hasNext()

 
/**
 *Output:
 */
import java.util.Scanner;
public class MainClass {
  public static void main(String args[]) {
    Scanner conin = new Scanner(System.in);
    int count = 0;
    double sum = 0.0;
    System.out.println("Enter numbers to average.");
    while (conin.hasNext()) {
      if (conin.hasNextDouble()) {
        sum += conin.nextDouble();
        count++;
      } else {
        String str = conin.next();
        if (str.equals("done"))
          break;
        else {
          System.out.println("Data format error.");
          return;
        }
      }
    }
    System.out.println("Average is " + sum / count);
  }
}

Scanner: hasNextBoolean()

 
/*
String: string
boolean: true
boolean: false
int: 1
int: 2
int: 3
double: 4.12
 */
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Scanner;
public class MainClass {
  public static void main(String args[]) throws IOException {
    int i;
    double d;
    boolean b;
    String str;
    FileWriter fout = new FileWriter("test.txt");
    fout.write("string true false 1 2 3 4.12");
    fout.close();
    FileReader fin = new FileReader("Test.txt");
    Scanner src = new Scanner(fin);
     while (src.hasNext()) {
      if (src.hasNextInt()) {
        i = src.nextInt();
        System.out.println("int: " + i);
      } else if (src.hasNextDouble()) {
        d = src.nextDouble();
        System.out.println("double: " + d);
      } else if (src.hasNextBoolean()) {
        b = src.nextBoolean();
        System.out.println("boolean: " + b);
      } else {
        str = src.next();
        System.out.println("String: " + str);
      }
    }
    fin.close();
  }
}

Scanner: hasNextDouble()

 
/**
 *Output:
 */
import java.util.Scanner;
public class MainClass {
  public static void main(String args[]) {
    Scanner conin = new Scanner(System.in);
    int count = 0;
    double sum = 0.0;
    System.out.println("Enter numbers to average.");
    while (conin.hasNext()) {
      if (conin.hasNextDouble()) {
        sum += conin.nextDouble();
        count++;
      } else {
        String str = conin.next();
        if (str.equals("done"))
          break;
        else {
          System.out.println("Data format error.");
          return;
        }
      }
    }
    System.out.println("Average is " + sum / count);
  }
}

Scanner: hasNextInt()

 
/*
String: string
boolean: true
boolean: false
int: 1
int: 2
int: 3
double: 4.12
 */
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Scanner;
public class MainClass {
  public static void main(String args[]) throws IOException {
    int i;
    double d;
    boolean b;
    String str;
    FileWriter fout = new FileWriter("test.txt");
    fout.write("string true false 1 2 3 4.12");
    fout.close();
    FileReader fin = new FileReader("Test.txt");
    Scanner src = new Scanner(fin);
     while (src.hasNext()) {
      if (src.hasNextInt()) {
        i = src.nextInt();
        System.out.println("int: " + i);
      } else if (src.hasNextDouble()) {
        d = src.nextDouble();
        System.out.println("double: " + d);
      } else if (src.hasNextBoolean()) {
        b = src.nextBoolean();
        System.out.println("boolean: " + b);
      } else {
        str = src.next();
        System.out.println("String: " + str);
      }
    }
    fin.close();
  }
}

Scanner: hasNextLine()

 
import java.io.File;
import java.util.Scanner;
public class Main {
  public static void main(String[] args) throws Exception{
    File file = new File("data.txt");
    Scanner scanner = new Scanner(file);
    while (scanner.hasNextLine()) {
      String line = scanner.nextLine();
      System.out.println(line);
    }
  }
}

Scanner: next()

 
/**
 *Output:
 */
import java.util.Scanner;
public class MainClass {
  public static void main(String args[]) {
    Scanner conin = new Scanner(System.in);
    int count = 0;
    double sum = 0.0;
    System.out.println("Enter numbers to average.");
    while (conin.hasNext()) {
      if (conin.hasNextDouble()) {
        sum += conin.nextDouble();
        count++;
      } else {
        String str = conin.next();
        if (str.equals("done"))
          break;
        else {
          System.out.println("Data format error.");
          return;
        }
      }
    }
    System.out.println("Average is " + sum / count);
  }
}

Scanner: nextBoolean()

 
/*
String: string
boolean: true
boolean: false
int: 1
int: 2
int: 3
double: 4.12
 */
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Scanner;
public class MainClass {
  public static void main(String args[]) throws IOException {
    int i;
    double d;
    boolean b;
    String str;
    FileWriter fout = new FileWriter("test.txt");
    fout.write("string true false 1 2 3 4.12");
    fout.close();
    FileReader fin = new FileReader("Test.txt");
    Scanner src = new Scanner(fin);
     while (src.hasNext()) {
      if (src.hasNextInt()) {
        i = src.nextInt();
        System.out.println("int: " + i);
      } else if (src.hasNextDouble()) {
        d = src.nextDouble();
        System.out.println("double: " + d);
      } else if (src.hasNextBoolean()) {
        b = src.nextBoolean();
        System.out.println("boolean: " + b);
      } else {
        str = src.next();
        System.out.println("String: " + str);
      }
    }
    fin.close();
  }
}

Scanner: nextDouble()

 
/*
String: string
boolean: true
boolean: false
int: 1
int: 2
int: 3
double: 4.12
 */
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Scanner;
public class MainClass {
  public static void main(String args[]) throws IOException {
    int i;
    double d;
    boolean b;
    String str;
    FileWriter fout = new FileWriter("test.txt");
    fout.write("string true false 1 2 3 4.12");
    fout.close();
    FileReader fin = new FileReader("Test.txt");
    Scanner src = new Scanner(fin);
     while (src.hasNext()) {
      if (src.hasNextInt()) {
        i = src.nextInt();
        System.out.println("int: " + i);
      } else if (src.hasNextDouble()) {
        d = src.nextDouble();
        System.out.println("double: " + d);
      } else if (src.hasNextBoolean()) {
        b = src.nextBoolean();
        System.out.println("boolean: " + b);
      } else {
        str = src.next();
        System.out.println("String: " + str);
      }
    }
    fin.close();
  }
}

Scanner: nextInt()

 
/*
String: string
boolean: true
boolean: false
int: 1
int: 2
int: 3
double: 4.12
 */
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Scanner;
public class MainClass {
  public static void main(String args[]) throws IOException {
    int i;
    double d;
    boolean b;
    String str;
    FileWriter fout = new FileWriter("test.txt");
    fout.write("string true false 1 2 3 4.12");
    fout.close();
    FileReader fin = new FileReader("Test.txt");
    Scanner src = new Scanner(fin);
     while (src.hasNext()) {
      if (src.hasNextInt()) {
        i = src.nextInt();
        System.out.println("int: " + i);
      } else if (src.hasNextDouble()) {
        d = src.nextDouble();
        System.out.println("double: " + d);
      } else if (src.hasNextBoolean()) {
        b = src.nextBoolean();
        System.out.println("boolean: " + b);
      } else {
        str = src.next();
        System.out.println("String: " + str);
      }
    }
    fin.close();
  }
}

Scanner: nextLine()

 
import java.io.File;
import java.util.Scanner;
public class Main {
  public static void main(String[] args) throws Exception{
    File file = new File("data.txt");
    Scanner scanner = new Scanner(file);
    while (scanner.hasNextLine()) {
      String line = scanner.nextLine();
      System.out.println(line);
    }
  }
}

Scanner: useDelimiter(String pattern)

 
/*
 */
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Scanner;
public class MainClass {
  public static void main(String args[]) throws IOException {
    int count = 0; 
    double sum = 0.0; 
 
    FileWriter fout = new FileWriter("test.txt"); 
 
    fout.write("2, 3.4,    5,6, 7.4, 9.1, 10.5, done"); 
    fout.close(); 
 
    FileReader fin = new FileReader("Test.txt"); 
 
    Scanner src = new Scanner(fin); 
 
    src.useDelimiter(", *"); 
 
    while(src.hasNext()) { 
      if(src.hasNextDouble()) { 
        sum += src.nextDouble(); 
        count++; 
      } 
      else { 
        String str = src.next();  
        if(str.equals("done")) break; 
        else { 
          System.out.println("File format error."); 
          return; 
        } 
      } 
    } 
 
    fin.close(); 
    System.out.println("Average is " + sum / count); 
  }
}