java/io bugfixes and coverage; jni bugfixes; minor refactoring

classpath/java/io/File.java

@@ -0,0 +1,61 @@
+package java.io;
+
+public class File {
+  private final String path;
+
+  public File(String path) {
+    if (path == null) throw new NullPointerException();
+    this.path = path;
+  }
+
+  public File(String parent, String child) {
+    this(parent + "/" + child);
+  }
+
+  public File(File parent, String child) {
+    this(parent.getPath() + "/" + child);
+  }
+
+  public String getName() {
+    int index = path.lastIndexOf("/");
+    if (index >= 0) {
+      return path.substring(index + 1);
+    } else {
+      return path;
+    }
+  }
+
+  public String getPath() {
+    return path;
+  }
+
+  private static native String toAbsolutePath(String path);
+
+  public String getAbsolutePath() {
+    return toAbsolutePath(path);
+  }
+
+  private static native long length(String path);
+
+  public long length() {
+    return length(path);
+  }
+
+  private static native boolean exists(String path);
+
+  public boolean exists() {
+    return exists(path);
+  }
+
+  private static native void mkdir(String path);
+
+  public void mkdir() {
+    mkdir(path);
+  }
+
+  private static native void createNewFile(String path);
+
+  public void createNewFile() {
+    createNewFile(path);
+  }
+}