阅读以下程序，写出输出结果。
public class Compare {
public static void main(String[] args) {
String str1 = "abc";
String str2 = new String("abc");
String str3 = "ab" + "c";
String str4 = new String(str2);
String str5 = str1;
System.out.println(str1 == str2);
System.out.println(str2 == str3);
System.out.println(str2 == str4);
System.out.println(str5 == str1);
}
}
