Difference between revisions of "Java/C2/Strings/English"

Welcome

Learning Outcomes

create strings,add strings and perform basic string operations like converting to lower case and upper case.

Tools Used

Ubuntu 11.10, JDK 1.6 and

Eclipse 3.7'

Prerequisites

If not, for relevant tutorial please visit our website as shown

Strings

Before starting with Strings, we will first see the character data type.

Let us now switch to eclipse

Eclipse should contain the following code

public class StringDemo{

public static void main(String[] args){

}

}

We have created a class StringDemo and added the main method.

char star = '*';

This statement creates a variable with name star and of the typechar.

It can store exactly one character.

Let us print a word using a few characters.

char c1 = 'c';

char c2 = 'a';

char c3 = 'r';

'char c1equal to c'

'char c2equal to a'

'char c3 equal tor'

We have created three characters to make the wordcar.

Now let us use them to print the word.

System.out.print(c1);

System.out.print(c2);

System.out.print(c3);

Save and Run.

Point to output

System.out.print(c1);

System.out.print(c2);

System.out.print(c3);

Please note that I’m usingprint instead ofprintln so that all the characters are printed on the same line.

save the file and run it.

As we can see, the output is as expected.

But this method only prints the word but does not create one.

To create a word, we use theString data type.

Let us try it out.

String greet = “Hello Learner”;

Type' String greet'equal to Hello Learnerin quotes;

Note that the S in the data typeString is in uppercase.

We have use double quotes instead of single quotes as delimiters

This statement creates a variablegreet that is of the typeString

Now Let us print the message.

System.out.println(greet);

Save the file run it .

Point to output

Save the file and run it As we can see, the message has been stored in the variable and it has been printed.

Strings can also be added in Java.

let us see how to do so.

We'll store the name in a different variable.

String name = “Java”;

String msg = greet + name;

changeprintln(greet) toprintln(msg)

Save and Run.

Point to output

Now we’ll add the strings to make a message

'String msg'equal to'greet'plus name;

changeprintln(greet) toprintln(msg) save the file and run it.

We can see that the output shows the greeting and the name.

But there is no space separating them.

char SPACE = ' ';

Changegreet + name togreet + SPACE + name

Save and Run.

Point to output

char SPACE 'equal to ';

Note that I have used all uppercase letters in the variable name so that it is clear.

You can change it as you want.

Now let us add the space to the message.

'greet'plus'SPACE'plus name

save the file and run it

Now we can see the output is clear and as expected.

Let us look at a few basic string operations.

Change“Java” to“jAvA”

Save and Run.

Point to output

and a word “java” to uppercase.

Often, when users give input, we have values like this, in mixed case.

So Let us run the file to see the output.

As we can see t he output is not clean.

Let us use the String methods to clean the input.

greet = greet.toLowerCase();

name = name.toUpperCase();

Save and Run.

Point to output

'greet'equal to greet.toLowerCase();

This statement converts each character of the stringgreet to lowercase

'name 'equal to name.toUpperCase();

This statement converts each character of the string name to uppercase.

Save the file and Run  it.

As we can see, the output is now clean after we have used the String methods.

There are many more String methods and

We'll discuss them as we move on to complex topics.

Slide 6

Summary

In this tutorial we have learnt

- how to create strings and addstrings

- few string operations like converting to lower case and upper case

- Read about theconcat method of Strings in Java. - Find out how is it different from adding strings.

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