Difference between revisions of "Android App"

Revision as of 22:26, 5 August 2019

Methods are nothing but members of a class that provide a service for an object or perform some business logic.

Overloading: Multiple methods with the same name but different parameter lists.

In constructors:

Item item1 = new Item();
Item milk = new Item(“milk”, 0.99, 3);

String x = new String();
String y = new String(“Hello”);

In methods:

String x = new String("Hola, cómo estás");
x.substring(2);
x.substring(2, 5);
x.indexOf("h");
x.indexOf("h", 1);

Two methods that should be included in classes (Good practice to include it):

Returns data stored in an object as a String:
- Allows the contents of an object to be displayed
- Can format the contents whatever way you wish
- MUST return a String*
- MUST NOT take a parameter*

public String toString() {
    return name + ", " + day + " " + monthNames[month-1] + " " + year + ", " + address;
}

Example result:

"P. Sherman, 30 May 2003, 42 Wallaby Way, Sydney"

@@ Line 1: / Line 1: @@
-jjvggggggggj
+==Methods==
-v
+Methods are nothing but members of a class that provide a service for an object or perform some business logic.
+===Method Overloading===
+Overloading: Multiple methods with the same name but different parameter lists.
+'''In constructors:'''
+<syntaxhighlight lang="java">
+Item item1 = new Item();
+Item milk = new Item(“milk”, 0.99, 3);
+String x = new String();
+String y = new String(“Hello”);
+</syntaxhighlight>
+'''In methods:'''
+<syntaxhighlight lang="java">
+String x = new String("Hola, cómo estás");
+x.substring(2);
+x.substring(2, 5);
+x.indexOf("h");
+x.indexOf("h", 1);
+</syntaxhighlight>
+===Standard Methods===
+Two methods that should be included in classes (Good practice to include it):
+*toString
+*equals
+====The toString Methodg====
+*'''Returns data stored in an object as a String:'''
+**Allows the contents of an object to be displayed
+**Can format the contents whatever way you wish
+**MUST return a String*
+**MUST NOT take a parameter*
+<syntaxhighlight lang="java">
+public String toString() {
+    return name + ", " + day + " " + monthNames[month-1] + " " + year + ", " + address;
+}
+</syntaxhighlight>
+Example result:
+<syntaxhighlight lang="bash">
+"P. Sherman, 30 May 2003, 42 Wallaby Way, Sydney"
+</syntaxhighlight>