java file.renameTo返回false的原因及解决方案

public static void main(String[] args) throws IOException {
        File file1 = new File("D:\\aabb.xml");
        File file2 = new File("D:\\ccdd.xml");
        boolean b = file1.renameTo(file2);
        System.out.println(b); // true
    }

public static void main(String[] args) throws IOException {
        File file1 = new File("D:\\aabb.xml");
        FileWriter out = new FileWriter(file1);
        File file2 = new File("D:\\ccdd.xml");
        boolean b = file1.renameTo(file2);
        System.out.println(b);// false
    }

public static void main(String[] args) throws IOException {
        File file1 = new File("D:\\aabb.xml");
        FileWriter out = new FileWriter(file1);
        out.close();
        File file2 = new File("D:\\ccdd.xml");
        boolean b = file1.renameTo(file2);
        System.out.println(b);//true
    }

import java.io.File;
import java.io.IOException; 
public class TestRenameTo {
  public static void main(String[] args) {
    File file = new File("f:\\1.txt");
    if (!file.isFile()) {
      try {
        file.createNewFile();
      } catch (IOException e) {
        e.printStackTrace();
      }
    }
  //调用renameTo()前
    System.out.println(file.exists());
    file.renameTo(new File("f:\\2.txt"));
  //调用renameTo()后
    System.out.println(file.exists());
  }
}