String Common Method Test

String.Equals () How to use

Used to compare strings represented by a string of two objects

Public class stringequals {

Public Static void Main (string[] args) {

String s1=New string ("Hello");

String s2=New string ("Hello");

System.  out. println (S1==S2); False

System.   out. println (s1.equals (S2)); True

String s3= "Hello";

String s4= "Hello";

System.       out. println (S3==S4); True

System.      out. println (S3.equals (S4)); True

}

}

The object of a class cannot be compared directly with = = compared to two string objects that cannot be used to compare objects and constants

The test code for some string methods is as follows:

Package demo;

Stringmisc.java

This program demonstrates the length, charAt and GetChars

Methods of the String class.

//

Note:method GetChars requires a starting point

and ending point in the String. The starting point is the

Actual subscript from which copying starts. The ending point

is one past the subscript at which the copying ends.

Import javax.swing.*;

public class Stringmisc {

public static void Main (String args[])

{

String S1, OUTPUT,S2,S3;

Char chararray[];

S1 = new String ("Hello there");

Chararray = new char[5];

Output the string

Output = "S1:" + S1;

Test the Length method

Output + = "\nlength of S1:" + s1.length ();

Loop through the characters in S1 and display reversed

Output + = "\nthe string reversed is:";

for (int i = S1.length ()-1; I >= 0; i--)

Output + = S1.charat (i) + "";

Copy characters from string to char array

Meaning of the four parameters

1. The starting position of the copied character in the string

2. The last character to be copied in the string subscript plus 1

3. Target character array

4. The copied character is placed in the character array starting subscript

S1.getchars (0, 5, chararray, 0);

Output + = "\nthe character array is:";

for (int i = 0; i < chararray.length;i++)

Output + = chararray[I];

Test the Replace method

S2 = s1.replace ("E", "O"); Replace method is finished after the conversion is to return a new object, if you do not find a string to replace the original object

Output + = "\nthe replace method result is:" +S2;

Test the toUpperCase and Tplowercase

S2 = S1.touppercase (); toUpperCase is to capitalize all the strings

S3 = S1.tolowercase (); toLowerCase, right? All strings become lowercase

Output + = "\nthe Upper is:" +S2;

Output + = "\nthe Lower is:" +S3;

Test the trim//Remove the first space in the string

S2 = "Hello There";

S3 = "Hello There";

Output + = "\ n Add the Blank:" +s3.equals (S2);

S2 = S2.trim ();

Output + = "\ After Trim:" + s2.equals (S3);

Test the ToCharArray//Put the string in a character array

Char array[] = S1.tochararray ();

Output + = "\ntochararray:";

for (int i = 0; i < array.length;i++)

Output + = array[I];

Joptionpane.showmessagedialog (null, OUTPUT,

"Demonstrating String Class constructors",

Joptionpane.information_message);

System.exit (0);

}

}

String Common Method Test