How to Use substring and .concat

[lala]

Hello. I am new to Java and this forum. I apologize if this post is going to the wrong forum.
I would like to concatenate strings Hi and Hello World.
This is what I have:
// Declare variables
String sentence1;
String sentence2;

//Assign variables
sentence1 = "Hi. ";
sentence2 = "Hello World";
System.out.println("The index of first w in sentence2 = " + sentence2.indexOf('o'));
System.out.println("Concatenate sentence1 and sentence2: " + sentence1.concat(sentence2));

This give me HIHello World.
How do I put a space between Hi and Hello? I would like to use the substring method/function.
Thanks In Advance

[al_Marshy_1981]

why do you need substrings?

sentence1+=" "+sentence2;

[lala]

Thank you for responding al_Marshy_1981. I had that statement in my code & was happy with the results. Then I re-read the instructions that said "concatenate the variable containing "Hi" with a substring of the variable containing "Hello World".

And that's when my world went into a downward spiral. :-) I'm just not having any luck with substring.
Thanks again.

[Zack]

You only need a substring of sentence2. So, you can use sentence2.substring(0,5) or something (1,6; 2,3; or anything like that, according to what you pasted) to pick a substring. Just be careful you don't make it say "Hi Hell". ;)

Once you have the substring you can prepend sentence1 to it using the syntax that al Marshy provided.

[lala]

Thank you al_Marshy_1981 & Zack. I'm doing fine now.
Do I have to start a new post to ask a new question about dialogue boxes?

[Zack]

The general rule is that once a problem is outside the scope of a thread, it should have its own thread. So, in your case, yes.

[lala]

Thanks again.
lala