public class HelloWorld { public static void main(String args[]) { // Java string class methods /* String str="Hello World"; // index finding System.out.println(str.indexOf("o")); System.out.println(str.indexOf("o",5)); // char at index System.out.println(str.charAt(7)); //substring System.out.println(str.substring(3)); System.out.println(str.substring(3,7)); System.out.println(str.contains("S")); //is empty System.out.println(str.isEmpty()); System.out.println("".isEmpty()); //upper lower System.out.println(str.toUpperCase()); System.out.println(str.toLowerCase()); //trim -> removes extra spaces at beg & end System.out.println(" hey...! ".trim()); // split -> spilts strings into array str="apple,nokia,samsung,lenovo"; str.split(","); System.out.println(str); // join //str.join(",","apples","oranges,"); */ String s1=""; System.out.println(s1); System.out.println(s1.length()); //java.lang.NullPointerException. // a value was null & you're calling method on that /* s1=null; System.out.println(s1.length()); */ s1=null; if(s1!=null) System.out.println(s1.length()); else System.out.println("you have null string"); // concatination of strings String s2=""; s1="hey"; s2="sree"; String s3 = s1+" "+s2; System.out.println(s3); s1="hey"; s2="hari"; s3=s1.concat(s2); System.out.println(s3); // comparison of strings s1="Hello"; s2="Hello"; s3="hEllo"; String s4=new String("Hello"); System.out.println(s1==s2); System.out.println(s1==s4); System.out.println(s1.equals(s4)); //use equals method when comparing the strings //becz it compares the contents of strings System.out.println(s1.equalsIgnoreCase(s3)); //ignores whether capital or small // Escape sequences s1="\"Hello\""; System.out.println(s1); s1="\'Hello\'"; System.out.println(s1); s1="\nHello\n"; System.out.println(s1); s1="\tHello\t"; System.out.println(s1); s1="Java Programming"; System.out.println(s1); System.out.println(s1.length()); char first=s1.charAt(0); // java.lang.StringIndexOutOfBoundsException /* char last=s1.charAt(16); System.out.println(last); */ for (int i = 0; i <s1.length() ; i++) { System.out.print(s1.charAt(i)); System.out.print(","); } System.out.println(); int index=s1.indexOf('o'); System.out.println(index); //prints -1 if it won't finds index=s1.indexOf('Z'); System.out.println(index); //index of string as well index=s1.indexOf("Pro"); System.out.println(index); // find after skipping some chars index=s1.indexOf('a',10); System.out.println(index); // contains or not (return true or false) System.out.println(s1.contains("Pro")); System.out.println(s1.contains("pro")); // trim -> removes extra spaces s2=" hey sree! "; System.out.println(s2.trim()); System.out.println(s2); s2=" programming "; s3=s2.trim(); System.out.println(s2); System.out.println(s3); s4="sree"; System.out.println(s4.toUpperCase()); System.out.println(s4); s1="Java Programming"; s2=s1.substring(3); //a Programming System.out.println(s2); // J a v a P r o g r a m m i n g // 0 1 2 3 4 5 6 7 8 9 10 s2=s1.substring(3,6); // a P System.out.println(s2); // StringIndexOutOfBoundsException /* s2=s1.substring(25); //a Programming System.out.println(s2); */ } }
Friday, 5 August 2016
Java String classes
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