> For the complete documentation index, see [llms.txt](https://nissan-goldberg.gitbook.io/java101/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://nissan-goldberg.gitbook.io/java101/lesson-6-strings-junit-and-recursion/useful-string-functions-and-more.md).

# Useful String functions and more

## Java

## `StringBuilder`

```java
StringBuilder str = new StringBuilder();

str.append("Hello");
str.append("World");

System.out.println(str.toString());
```

```
HelloWorld
```

## `equals()`

### syntax

```java
public boolean equals(Object anotherObject)
```

### example

```java
String myStr1 = "Hello";
String myStr2 = "World";

System.out.println("Hello".toLowerCase().equals("hello")); // Returns true
System.out.println(myStr1.equals(myStr2));                 //Returns false
```

## `compareTO()`

```java
String myStr1 = "Hello";
String myStr2 = "Hello";
System.out.println(myStr1.compareTo(myStr2)); // Returns 0 because they are equal

System.out.println("be".compareTo("bee"));
```

```
0
-1
```

## `join()`

```java
String date = String.join("/","30","04","2021");    
System.out.print(date);

String time = String.join(":", "12","10","10");  
System.out.println(" "+time);
```

```
30/04/2021 12:10:10
```

## `split()`

```java
String[] strings = "30-04-2021".split("-");

for (int i = 0; i < strings.length; i++)
     System.out.print(strings[i] + " ");
```

```
30 04 2021
```

## more useful functions

```java
str.indexOf();
str.substring();
str.replace();
Interger.parseInt();
assertTrue()
```