Java String padha ()

Mbandhingake obyek kanggo kesetaraan minangka salah sawijining operasi pemrograman sing paling penting. Nanging, kanggo kabeh cetha ing donya numerik, iku ora tansah cetha carane mbandhingaké jinis data liyane. Kelas Obyek Jawa , sing dhasar, nemtokake cara sing padha () lan compareTo () kanggo mbandhingake. String kelas overrides sawijining padha () cara. Metode Java String padha () mbandhingake rong senar miturut isine. String equals() method signature katon kaya iki:

public boolean equals(Object anotherObject) 

String equals () cara mbandhingake string menyang obyek sing ditemtokake. Yen strings padha, bali bener, digunakake palsu. Sampeyan bisa uga kepingin weruh kenapa ora mbandhingake senar nggunakake operator perbandingan == ? Ing kasunyatan, iki uga bisa, nanging asil bakal rada beda. Kasunyatane yaiku operator == mbandhingake alamat ing memori. Dadi yen s1 == s2 ngasilake true , loro strings iki duwe alamat sing padha ing memori. Ing wektu sing padha, equals mriksa isi strings kanggo kesetaraan. Ayo njupuk conto mbandhingake rong senar.

public class StringEqualsTest {
   //program to test Java equals() method
   public static void main(String[] args) {
       String myString1 = "here is my favorite string";
       String myString2 = "here is my favorite string"; //this string is the same as the previous one, at least we think so 
       String myString3 = "here is My favorite string"; //this string looks a little bit like previous two, but the first letter is big M instead of small m       
       String myString4 = new String("here is my favorite string");
//here we create a String in an object manner… Why? Find out soon  
       String myString5 = "equals to myString1? No, not at all..."; //here we have absolutely different string. Just for fun 
    //let’s compare myString1 with myString2 using “==” operator  
       System.out.println(myString1 == myString2); //true
    //let’s compare myString1 with myString4 using “==” operator  
       System.out.println(myString1 == myString4); //false    
//and now we are going to use equals() method to compare myString1 with myString4, myString2 and myString5  
     System.out.println(myString1.equals(myString4));//true
       System.out.println(myString1.equals(myString2));//true
       System.out.println(myString1.equals(myString5)); //false

   }
}

Output saka program iki yaiku: Ayo padha nliti babagan apa sing kedadeyan ing kene. Nalika kita nggawe senar, diselehake ing blumbang senar, area khusus memori. String njupuk bagean gedhe saka kabeh obyek ing program gedhe. Dadi kanggo nyimpen memori String Pool digawe, ngendi senar karo teks sing perlu diselehake. Mengko pranala mentas digawe deleng wilayah memori padha, ana ora perlu kanggo nyedhiakke memori tambahan saben wektu. Yen sampeyan nggawe string tanpa operator anyar, yaiku nalika sampeyan nulis

String  myStringName = "...........................................", 

utawa kaya, program mriksa yen ana String karo teks kuwi ing blumbang String. Yen ya, ora ana String anyar sing bakal digawe. Lan link anyar bakal nuding alamat sing padha ing Kolam String ing ngendi String kasebut wis disimpen. Dadi nalika kita nulis ing program

 String myString1 = "here is my favorite string";
 String myString2 = "here is my favorite string";

referensi myString1 nuduhke persis panggonan sing padha ing memori myString2 . Prentah pisanan nggawe senar anyar ing Kolam String kanthi teks sing dibutuhake, lan nalika nomer loro, mung diarani area memori sing padha karo myString1 . Nanging string myString4 digawe minangka obyek nggunakake operator anyar . Operator iki nyedhiyakake area anyar ing memori kanggo obyek nalika digawe. A string digawe karo anyar

 String myString1 = new String ("here is my favorite string");
 String myString2 = new String ("here is my favorite string");

ora tiba ing Kolam String, nanging dadi obyek sing kapisah, sanajan teks kasebut cocog karo senar sing padha saka Kolam String. Menapa malih, yen kita mbandhingaké strings nggunakake String padha () cara, bakal mriksa ora alamat, nanging isi senar, urutan karakter ing strings. Lan yen teks ing strings padha, iku ora Matter carane padha digawe lan ngendi padha disimpen, ing String Pool, utawa ing wilayah memori kapisah. Pramila myString1 , myString2 lan myString4 padha karo perbandingan iki. Miturut cara, sampeyan wis ngeweruhi sing String padha () cara ngijini sampeyan kanggo bener mbandhingaké strings ing kasus-sensitif? Tegese, yen kita mbandhingake senar "senarku" karo senar "Senarku" lan "STRINGKU" kita entuk palsu.

public class StringEqualsTest {

   public static void main(String[] args) {

       String myString1 = new String ("here is my favorite string");
       String myString2 = new String ("here is My favorite string");
       String myString3 = new String("HERE IS MY FAVORITE STRING");
      
       System.out.println(myString1.equals(myString2)); //false because first string myString1 has small m and myString2 has big M instead 
       System.out.println(myString1.equals(myString3));//false because myString1 is in lowercase while myString3 is in uppercase

   }
}

Output ing kene: Kanggo mbandhingake string kanthi cara sing ora sensitif huruf, Jawa nduweni metode sing meh padha karo :

boolean equalsIgnoreCase​(String anotherString)

Ayo digunakake ing conto kita.

public class StringEqualsTest {

   public static void main(String[] args) {

       String myString1 = new String ("here is my favorite string");
       String myString2 = new String ("here is My favorite string");
       String myString3 = new String("HERE IS MY FAVORITE STRING");
     /* here we are going to use the brother of equals() method, equalsIgnoreCase(). It can help to check user input when case isn’t 
important */ 
       System.out.println(myString1.equalsIgnoreCase(myString2));

       System.out.println(myString1.equalsIgnoreCase(myString3));

   }
}

Saiki output yaiku: