CareerCup

String s = "What is the length";
                int i=0;
		try{	
			while(true)
			{
				s.charAt(i);
				i++;
			}
		}
		catch(StringIndexOutOfBoundsException e)
		{
			System.out.println("the length is " + i);
		}

class test
{
public static void main(String[] args){
String str="A String";
char str1[]=str.toCharArray();
int i=0;
for(char s : str1){
i++;
}
System.out.println("Length =" + i);
}
}

String name="TestText";
		try {
			File rawfile=new File("filename");
			
			FileWriter file=new FileWriter(rawfile);
			file.write(name);
			file.close();
			
			FileReader reader=new FileReader(rawfile);
			int readByte=reader.read();

			int i=0;
			while(readByte!=-1)
			{i++;
				
			readByte=reader.read();
			}
			
			System.out.println("length is   :"+i);
	
		
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

You cannot solve this without invoking any method within String class. If that is a constraint, then pass the string as a jstring to a JNI method and then within that method do this:

const char* array = env->GetStringUTFChars(myString, 0);

Then inside your JNI method, count till you reach "\0".

Is java string doesn't end with '\0' ?

I wasn't able to find the exact length or number of chars in the string but i found the approximate length withing range of 4 characters. Here is the code:

public class Sizeof
{
    public static void main (String [] args) throws Exception
    {
        // Warm up all classes/methods we will use
        runGC ();
        usedMemory ();
        // Array to keep strong references to allocated objects
        final int count = 100000;
        StringBuilder [] strings = new StringBuilder [count];
        
        long heap1 = 0;
        // Allocate count+1 objects, discard the first one
        for (int i = -1; i < count; ++ i)
        {
            StringBuilder string = null;
            
            // Instantiate your data here and assign it to object
            /*
             * 64-> 1-2 , 72 -> 3-6 , 80 -> 7-10 , 88 -> 11-14
             */
            string = new StringBuilder ("12345671234"); 
            
            if (i >= 0)
            	strings [i] = string;
            else
            {
            	string = null; // Discard the warm up object
                runGC ();
                heap1 = usedMemory (); // Take a before heap snapshot
            }
        }
        runGC ();
        long heap2 = usedMemory (); // Take an after heap snapshot:
        
        final int size = Math.round (((float)(heap2 - heap1))/count);
        System.out.println ("'before' heap: " + heap1 +
                            ", 'after' heap: " + heap2);
        System.out.println ("heap delta: " + (heap2 - heap1) +
            ", {" + strings [0].getClass () + "} size = " + size + " bytes");
        int lower=3 ; int upper = 6; int increment=0; 
        if(size==64) {System.out.println("Num of char= 1 or 2");}
        else if(size==72) {System.out.println("Num of char= 3 to 6");}
        else {increment=((size-72)/8)*4;   System.out.println("Num of char= "+""+ (lower+increment) +" to "+""+(upper+increment));}
        
        for (int i = 0; i < count; ++ i) strings [i] = null;
        strings = null;
    }
    private static void runGC () throws Exception
    {
        // It helps to call Runtime.gc()
        // using several method calls:
        for (int r = 0; r < 4; ++ r) _runGC ();
    }
    private static void _runGC () throws Exception
    {
        long usedMem1 = usedMemory (), usedMem2 = Long.MAX_VALUE;
        for (int i = 0; (usedMem1 < usedMem2) && (i < 500); ++ i)
        {
            s_runtime.runFinalization ();
            s_runtime.gc ();
            Thread.currentThread ().yield ();
            
            usedMem2 = usedMem1;
            usedMem1 = usedMemory ();
        }
    }
    private static long usedMemory ()
    {
        return s_runtime.totalMemory () - s_runtime.freeMemory ();
    }
    
    private static final Runtime s_runtime = Runtime.getRuntime ();
} // End of class

String name="kiran";
		int i=0;
		for(char c:name.toCharArray())
		{
			i++;
		}
		System.out.println("The lenght of a String is "+i);

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