java.io.ObjectOutputStream.PutField.put(String name, double val) 方法把指定的雙字段的值放到持久性字段。

聲明

以下是java.io.ObjectOutputStream.PutField.put()方法的聲明

public abstract void put(String name, double val)

參數

• name -- 可序列化字段的名稱

• val -- 分配給字段的值

返回值

此方法無返回值。

異常

• IllegalArgumentException -- 如果name不匹配一個序列化的字段，其字段正被寫入，或者指定字段的類型不是double

例子

下麵的示例演示java.io.ObjectOutputStream.PutField.put()方法的用法。

package com.yiibai;

import java.io.*;

public class ObjectOutputStreamDemo implements Serializable {

   public static void main(String[] args) {

      try {

         // create a new file with an ObjectOutputStream
         FileOutputStream out = new FileOutputStream("test.txt");
         ObjectOutputStream oout = new ObjectOutputStream(out);

         // write something in the file
         oout.writeObject(new Example());
         oout.flush();
         oout.close();

         // create an ObjectInputStream for the file we created before
         ObjectInputStream ois =
                 new ObjectInputStream(new FileInputStream("test.txt"));

         // read an object from the stream and cast it to Example
         Example a = (Example) ois.readObject();

         // print var of a
         System.out.println("" + a.var);

      } catch (Exception ex) {
         ex.printStackTrace();
      }

   }

   static public class Example implements Serializable {

      static double var = 1.875d;
      // assign a new serialPersistentFields 
      private static final ObjectStreamField[] serialPersistentFields = {
         new ObjectStreamField("var", Double.TYPE)
      };

      private void readObject(ObjectInputStream in)
              throws IOException, ClassNotFoundException {

         // get the field and assign it at var
         ObjectInputStream.GetField fields = in.readFields();

         // get var
         var = fields.get("var", 0d);
      }

      private void writeObject(ObjectOutputStream out)
              throws IOException {

         // write into the ObjectStreamField array the variable var
         ObjectOutputStream.PutField fields = out.putFields();
         fields.put("var", var);
         out.writeFields();

      }
   }
}

讓我們編譯和運行上麵的程序，這將產生以下結果：

1.875