== and equals in java

Today I tried an equal symbol in java, and then wrote down the result, I hope you can correct me.

1. == and equals in String

      
	 public static void main(String[] args) {
 String a="abc";
 String b="abc";
 String c=new String("abc");
 String d=new String("abc");
 System.out.println(a==b);
 System.out.println(c==d);
 System.out.println(a.equals(b));
 System.out.println(a.equals(c));
}