stringconversion.java

是一款用JAVA 编写的编译器 具有很强的编译功能

/*
 * Copyright 1997-1998 Sun Microsystems, Inc.  All Rights Reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 */

/*
 * @test
 * @bug 4030173 4071548
 * @summary Verify correct conversion of non-string arguments in string concatenation.
 * @author maddox
 *
 * @compile StringConversion.java
 * @run main StringConversion
 */

class FooBar {
    public String toString(){
	return null;
    }
}

public class StringConversion {

    static void check(int testid, String have, String expect)
		throws Exception {
	if ((have == null && have != expect) ||
	        (have != null && !have.equals(expect))) {
	    String msg =
		"TEST " + testid + ": HAVE \"" +
		have + "\" EXPECT \"" + expect + "\"";
	    System.out.println("StringConversion: " + msg);
	    throw new Exception(msg);
	}
    }

    public static void main(String[] args) throws Exception {

	String s;
	String n = null;
	Object o = null;
	FooBar m = new FooBar();

	// Null reference must be converted to "null"

	// Conversion will be done by 'StringBuffer.append'.
	s = "foo" + n;
	check(11, s, "foonull");
	s = n + "bar";
	check(12, s, "nullbar");
	s = "foo" + o;
	check(13, s, "foonull");
	s = o + "bar";
	check(14, s, "nullbar");

	// Conversion will be done by 'String.valueOf'.
	s = "" + n;
	check(21, s, "null");
	s = n + "";
	check(22, s, "null");
	s = "" + o;
	check(23, s, "null");
	s = o + "";
	check(24, s, "null");

	// Null 'toString' result must be converted to "null"

	// Conversion will be done by 'StringBuffer.append'.
	s = "foo" + m;
	check(31, s, "foonull");
	s = m + "bar";
	check(32, s, "nullbar");

	// Conversion will be done by 'String.valueOf'.
	s = "" + m;
	check(43, s, "null");
	s = m + "";
	check(44, s, "null");

	// A character array must be converted as if by
	// 'toString', i.e., it is treated as an 'Object'.

	s = "polymorph";
	char[] ca = {'i', 's', 'm'};

	check(51, s + ca, s + ca.toString());
	check(52, ca + s, ca.toString() + s);

	System.out.println("OK");
    }
}