8305457: Implement java.io.IO

Reviewed-by: naoto, smarks, jpai, jlahoda

src/java.base/share/classes/java/io/ProxyingConsole.java

@@ -81,6 +81,42 @@ final class ProxyingConsole extends Console {
         return reader;
     }
 
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public Console println(Object obj) {
+        synchronized (writeLock) {
+            delegate.println(obj);
+        }
+        return this;
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public Console print(Object obj) {
+        synchronized (writeLock) {
+            delegate.print(obj);
+        }
+        return this;
+    }
+
+    /**
+     * {@inheritDoc}
+     *
+     * @throws IOError {@inheritDoc}
+     */
+    @Override
+    public String readln(String prompt) {
+        synchronized (writeLock) {
+            synchronized (readLock) {
+                return delegate.readln(prompt);
+            }
+        }
+    }
+
     /**
      * {@inheritDoc}
      */