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- What is the output of the following segment? int n = 35; while( true ) { if( n <= 1 ) break; n = n/2; System.out.println(n); } // end while 17 8 4 2 1
- What is the output of the following segment? int i = 0; int j = 12; while( i < j ) { i += 1; j -= 1; System.out.println(i + " " + j); } // end while 1 11 2 10 3 9 4 8 5 7 6 6
- Trace the execution of the following code fragments to determine their outputs. double x = -1.0; do { System.out.print(x); x = x + 0.5; } while ( x <= 1.0 ); -1.0 -0.5 0.0 0.5 1. for ( int r = 1; r <= 4; r++) { for ( int c = 1; c <= r; c++) System.out.print(“*”);
System.out.println(); }
**
- Write a loop (of any kind) that will generate the following output: 10 9 8 7 6 5 4 3 2 1 0 for ( int k = 10; k >= 0; k--) System.out.print( k + “ “ );
- Write a code segment inside main to do the following:
- Write a while loop to input Strings using methods from Scanner class
- Prompt the user whether to enter another String (no/n stop)
- Accumulate the Strings in a String variable out with a space between the Strings and print out after the while loop Scanner scan = new Scanner(System.in); String output = “”; while (true) { System.out.println(“Please enter a string”); String output += scan.next(); System.out.print(“Do you want to enter another one (yes/no)?”); String temp = scan.next(); if(temp.equalsIgnoreCase(“no”) || temp.equalsIgnoreCase(“n”)) break; } System.out.println(output);
- Write a loop to input numbers (ints) using methods from Scanner class until the user enter -1. Sum the numbers in an int variable sum. Finally, print out the sum value of all numbers except the last number, -1. Scanner scan = new Scanner(System.in); int sum = 0; while (true)
//File Student.java import java.util.ArrayList; import java.util.Iterator; public class Student { private String fName; private String lName; private ArrayList scores; //Constructor public Student (String fName, String lName) { this.fName = fName; this.lName = lName; scores = new ArrayList (); } //Accessor public String getFirstName() { return fName; } public String getLastName() { return lName; } public ArrayList getScores() { ArrayList temp = new ArrayList(); Iterator iter = scores.iterator(); while(iter.hasNext()) { temp.add((Integer)iter.next()); } return temp; //Wrong implementation //return scores; } //mutator public void setFirstName(String fName) { this.fName = fName;
public void setLastName(String lName) { this.lName = lName; } public void setScores(ArrayList s) { Iterator iter = s.iterator(); while(iter.hasNext()) { scores.add((Integer)iter.next()); } //Wrong implementation //scores = s; } public boolean equals(Student std) { if(fName.equals(std.getFirstName()) && lName.equals(std.getLastName())) return true; else return false; } public String toString() { return fName + " " + lName + " : " + scores; } } //File StudentTest import java.util.ArrayList; public class StudentTest { public static void main(String[] args) { Student s1 = new Student("David", "Yang"); Student s2 = new Student("David", "Yang"); Student s3 = new Student("Yanxiang", "Yang"); ArrayList scores = new ArrayList(); scores.add(100); scores.add(99); scores.add(95);
Print the rounded average of the integers stored in array list.
int total = 0.0; for ( int k = 0; k < list.length; k++ ) total += list[k]; double average =(int)((double)total/list.length + 0.5); System.out.println( “Average “ + average );
Print the largest and smallest integers stored in array list.
int max = list[0]; int min = list[0]; for ( int k = 0; k < list.length; k++ ) { if ( list[ k ] > max ) max = list[ k ]; if ( list[ k ] < min ) min = list[ k ]; } System.out.println( “Smallest “ + min + “ Largest “ + max );
- Objects of the DataSet class may be used to accumulate various statistics about a set of real ( double ) data values, for example, the test scores of students in a class. Give a partial implementation of the DataSet class that allows the count, mean, maximum and minimum of the data values to be calculated public class DataSet { //Instance Variables private double sum; private double min; private double max; private int count; //Constructor public DataSet() { sum = 0.0; min = 0.0; max = 0.0; count = 0; } //Mutator: add a data value to the data set
public void add( double item ) { count++; sum += item; if ( count == 1 ) { min = item; max = item;} else if ( item < min ) min = item; else if ( item > max ) max = item; } //Accessors public int getCount() { return count; } public double getMean() { return mean; } public double getMinimum() { return min; } public double getMaximum() { return max; } } Write an application that builds a DataSet object for the gpa’s of a set of students. First, input the individual gpa’s, and add them to the DataSet (negative value to terminate loop). After entering all gpas, report whether the gpa is above, equal to, or below the average gpa of the set. public class ProcessGPAs { public static void main( String[] args ) { Scanner inp = new Scanner( System.in ); DataSet set = new DataSet(); System.out.println(“Enter student GPA’s ending with -1.0”); double gpa = inp.nextDouble(); while ( gpa >= 0.0 ) { set.add( gpa ); gpa = inp.nextDouble(); } double mean = set.getMean(); System.out.println(“Output gpa status for all students: ”); while ( inp.hasNext() ); { gpa = inp.nextDouble();
