Java – Shortラッパークラスの使い方

// App.java
public class App {
    public static void main(String[] args) {
        // コンストラクタを使用してShortオブジェクトを生成
        Short shortObj1 = new Short((short) 10);
        
        // オートボクシングを使用してShortオブジェクトを生成
        Short shortObj2 = 20; // 自動的にShortオブジェクトに変換される
        System.out.println("shortObj1: " + shortObj1);
        System.out.println("shortObj2: " + shortObj2);
    }
}

shortObj1: 10
shortObj2: 20

// App.java
public class App {
    public static void main(String[] args) {
        // 文字列をshortに変換
        short value = Short.parseShort("123");
        System.out.println("Parsed short value: " + value);
    }
}

Parsed short value: 123

// App.java
public class App {
    public static void main(String[] args) {
        Short shortObj = 45;
        // Shortオブジェクトを文字列に変換
        String strValue = shortObj.toString();
        System.out.println("String value: " + strValue);
    }
}

String value: 45

// App.java
public class App {
    public static void main(String[] args) {
        Short shortObj1 = 10;
        Short shortObj2 = 20;
        
        // Shortオブジェクトを比較
        int result = shortObj1.compareTo(shortObj2);
        
        if (result < 0) {
            System.out.println("shortObj1 is less than shortObj2");
        } else if (result > 0) {
            System.out.println("shortObj1 is greater than shortObj2");
        } else {
            System.out.println("shortObj1 is equal to shortObj2");
        }
    }
}

shortObj1 is less than shortObj2

// App.java
import java.util.ArrayList;
import java.util.List;
public class App {
    public static void main(String[] args) {
        // Shortオブジェクトをリストに格納
        List<Short> shortList = new ArrayList<>();
        shortList.add((short) 10);
        shortList.add((short) 20);
        shortList.add((short) 30);
        // リストの内容を表示
        for (Short s : shortList) {
            System.out.println("Value: " + s);
        }
    }
}

Value: 10
Value: 20
Value: 30

// App.java
public class App {
    public static void main(String[] args) {
        Short value = 15;
        printShortValue(value);
    }
    // Shortオブジェクトを引数として受け取るメソッド
    public static void printShortValue(Short value) {
        System.out.println("Short value: " + value);
    }
}

Short value: 15

// App.java
public class App {
    public static void main(String[] args) {
        // 文字列をshortに変換
        short parsedValue = Short.parseShort("100");
        System.out.println("Parsed short: " + parsedValue);
        // shortを文字列に変換
        String strValue = Short.toString(parsedValue);
        System.out.println("String value: " + strValue);
    }
}

Parsed short: 100
String value: 100

// App.java
public class App {
    public static void main(String[] args) {
        // オートボクシング
        Short shortObj = 10; // プリミティブ型shortがShortオブジェクトに自動変換
        // アンボクシング
        short primitiveShort = shortObj; // Shortオブジェクトがプリミティブ型shortに自動変換
        System.out.println("Short object: " + shortObj);
        System.out.println("Primitive short: " + primitiveShort);
    }
}

Short object: 10
Primitive short: 10

// App.java
public class App {
    public static void main(String[] args) {
        Short shortObj = null;
        try {
            // アンボクシングでNullPointerExceptionが発生
            short primitiveShort = shortObj;
        } catch (NullPointerException e) {
            System.out.println("NullPointerException occurred: " + e.getMessage());
        }
    }
}

NullPointerException occurred: null

// App.java
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
public class App {
    public static void main(String[] args) {
        String url = "jdbc:mysql://localhost:3306/mydatabase";
        String user = "username";
        String password = "password";
        try (Connection conn = DriverManager.getConnection(url, user, password)) {
            String query = "SELECT short_column FROM my_table WHERE id = ?";
            PreparedStatement pstmt = conn.prepareStatement(query);
            pstmt.setInt(1, 1);
            ResultSet rs = pstmt.executeQuery();
            if (rs.next()) {
                // データベースからshort型のデータを取得
                Short shortValue = rs.getShort("short_column");
                System.out.println("Short value from database: " + shortValue);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

// App.java
import java.io.*;
import java.net.*;
public class App {
    public static void main(String[] args) {
        try (ServerSocket serverSocket = new ServerSocket(12345)) {
            Socket clientSocket = serverSocket.accept();
            DataInputStream in = new DataInputStream(clientSocket.getInputStream());
            DataOutputStream out = new DataOutputStream(clientSocket.getOutputStream());
            // クライアントからshort型のデータを受信
            short receivedShort = in.readShort();
            System.out.println("Received short: " + receivedShort);
            // Shortオブジェクトを使用してデータを送信
            Short shortToSend = 42;
            out.writeShort(shortToSend);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

// App.java
import java.io.*;
public class App {
    public static void main(String[] args) {
        String fileName = "shortData.dat";
        try (DataOutputStream dos = new DataOutputStream(new FileOutputStream(fileName))) {
            // Shortオブジェクトを使用してデータを書き込む
            Short shortToWrite = 123;
            dos.writeShort(shortToWrite);
        } catch (IOException e) {
            e.printStackTrace();
        }
        try (DataInputStream dis = new DataInputStream(new FileInputStream(fileName))) {
            // ファイルからshort型のデータを読み込む
            short readShort = dis.readShort();
            System.out.println("Read short from file: " + readShort);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}