1. Loops
public class Loops {
public static void main(String [] args) throws Throwable {
loop:
while (true) {
for (int i = 0; i < 100; i++) {
int c = System.in.read();
if (c == 'x') {
continue loop;
} else if (c == 'y') {
break loop;
} else {
System.out.print((char)c);
//System.out.flush();
}
}
System.out.println(">");
}
System.out.println();
}
}
public class Loops {
public static void main(String [] args) throws Throwable {
loop:
while (true) {
for (int i = 0; i < 100; i++) {
int c = System.in.read();
if (c == 'x') {
continue loop;
} else if (c == 'y') {
break loop;
} else {
System.out.print((char)c);
//System.out.flush();
}
}
System.out.println(">");
}
System.out.println();
}
}
2. ScopeExample
public class ScopeExample {
private int i=1;
public void firstMethod() {
int i=4, j=5;
this.i = i + j;
secondMethod(7);
}
public void secondMethod(int i) {
this.i = i;
}
}
3. StmtLabels
/*
* This file tests a few variations on labelled break/continue statements.
*/
public class StmtLabels {
public static void main(String[] args) {
int count = 0;
// test break label on compound statement
lab1:
{
System.out.println("before lab1");
if ( count == 0 )
{ break lab1; }
System.out.println("after lab1");
}
// test break label on an if statement
System.out.println("before lab1a");
lab1a:
if ( count == 0 ) {
break lab1a;
} else {
System.out.println("else clause; not break to lab1a");
}
System.out.println("after lab1a");
// test continue label on compound statement
lab2:
{
System.out.println("before lab2");
//if ( count == 0 )
//{ continue lab2; } CAN NOT continue A COMPOUND STMT
System.out.println("after lab2");
}
}
}
4. TestForLoop
public class TestForLoop {
public static void main(String[] args) {
for ( int i = 0; i < 10; i++ )
System.out.println(i + " squared is " + (i*i));
}
}
5. TestInitBeforeUse
public class TestInitBeforeUse {
public void doComputation() {
int x = (int)(Math.random() * 100);
int y;
int z;
if (x > 50) {
y = 9;
}
z = y + x; // Possible use before initialization
}
}
6. TestScoping
public class TestScoping {
public static void main(String[] args) {
ScopeExample scope = new ScopeExample();
scope.firstMethod();
}
}
7. TestShift
public class TestShift {
public static String bitPattern(int value) {
int BIT1_MASK = 1;
final char[] bits = new char[32];
for ( int i = 31; i >= 0; i-- ) {
if ( (value & BIT1_MASK) == 1 ) {
bits[i] = '1';
} else {
bits[i] = '0';
}
value >>>= 1;
}
return new String(bits);
}
public static void main(String[] args) {
int num1 = 1357;
int num2 = -1357;
System.out.println("num1 (" + num1 + ") as a bit pattern: " + bitPattern(num1));
System.out.println("num2 (" + num2 + ") as a bit pattern: " + bitPattern(num2));
System.out.println("" + num1 + " >> 5 = (" + (num1 >> 5) + ") " + bitPattern(num1 >> 5));
System.out.println("" + num2 + " >> 5 = (" + (num2 >> 5) + ") " + bitPattern(num2 >> 5));
System.out.println("" + num1 + " >>> 5 = (" + (num1 >>> 5) + ") " + bitPattern(num1 >>> 5));
System.out.println("" + num2 + " >>> 5 = (" + (num2 >>> 5) + ") " + bitPattern(num2 >>> 5));
System.out.println("" + num1 + " << 5 = (" + (num1 << 5) + ") " + bitPattern(num1 << 5));
System.out.println("" + num2 + " << 5 = (" + (num2 << 5) + ") " + bitPattern(num2 << 5));
}
}
/*
num1 (1357) as a bit pattern: 00000000000000000000010101001101
num2 (-1357) as a bit pattern: 11111111111111111111101010110011
1357 >> 1 = 00000000000000000000001010100110
-1357 >> 1 = 11111111111111111111110101011001
1357 >> 5 = 00000000000000000000000000101010
-1357 >> 5 = 11111111111111111111111111010101
1357 >>> 5 = 00000000000000000000000000101010
-1357 >>> 5 = 00000111111111111111111111010101
1357 << 1 = 00000000000000000000101010011010
-1357 << 1 = 11111111111111111111010101100110
1357 << 5 = 00000000000000001010100110100000
-1357 << 5 = 11111111111111110101011001100000
*/
8. TestWhileLoops
public class TestWhileLoops {
public static void main(String[] args) {
test1();
test2();
test3();
test4();
}
private static void test1() {
System.out.println("Test #1 - while loop with block");
int i = 0;
while ( i < 10 ) {
System.out.println(i + " squared is " + (i*i));
i++;
}
}
private static void test2() {
System.out.println("Test #2 - while loop with single statement");
int i = 0;
while ( i < 10 )
System.out.println(++i + " squared is " + (i*i));
}
private static void test3() {
System.out.println("Test #3 - do-while loop with block");
int i = 0;
do {
System.out.println(i + " squared is " + (i*i));
i++;
} while ( i < 10 );
}
private static void test4() {
System.out.println("Test #4 - do-while loop with single statement");
int i = 0;
do
System.out.println(++i + " squared is " + (i*i));
while ( i < 10 );
}
}
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