Java/Data Type/Overflow
Содержание
Multiply two integers, checking for overflow.
<source lang="java">
import java.io.File; /*
* Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. * * */
public class Main {
/**
* Multiply two integers, checking for overflow.
*
* @param x a factor
* @param y a factor
* @return the product x*y
* @throws ArithmeticException if the result can not be represented as an
* int
* @since 1.1
*/
public static int mulAndCheck(int x, int y) {
long m = ((long)x) * ((long)y);
if (m < Integer.MIN_VALUE || m > Integer.MAX_VALUE) {
throw new ArithmeticException("overflow: mul");
}
return (int)m;
}
}
</source>
Multiply two long integers, checking for overflow.
<source lang="java">
import java.io.File; /*
* Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. * * */
public class Main {
/**
* Multiply two long integers, checking for overflow.
*
* @param a first value
* @param b second value
* @return the product a * b
* @throws ArithmeticException if the result can not be represented as an
* long
* @since 1.2
*/
public static long mulAndCheck(long a, long b) {
long ret;
String msg = "overflow: multiply";
if (a > b) {
// use symmetry to reduce boundry cases
ret = mulAndCheck(b, a);
} else {
if (a < 0) {
if (b < 0) {
// check for positive overflow with negative a, negative b
if (a >= Long.MAX_VALUE / b) {
ret = a * b;
} else {
throw new ArithmeticException(msg);
}
} else if (b > 0) {
// check for negative overflow with negative a, positive b
if (Long.MIN_VALUE / b <= a) {
ret = a * b;
} else {
throw new ArithmeticException(msg);
}
} else {
// assert b == 0
ret = 0;
}
} else if (a > 0) {
// assert a > 0
// assert b > 0
// check for positive overflow with positive a, positive b
if (a <= Long.MAX_VALUE / b) {
ret = a * b;
} else {
throw new ArithmeticException(msg);
}
} else {
// assert a == 0
ret = 0;
}
}
return ret;
}
}
</source>
Subtract two integers, checking for overflow.
<source lang="java">
import java.math.BigDecimal; /*
* Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. * * */
public class Main {
/**
* Subtract two integers, checking for overflow.
*
* @param x the minuend
* @param y the subtrahend
* @return the difference x-y
* @throws ArithmeticException if the result can not be represented as an
* int
* @since 1.1
*/
public static int subAndCheck(int x, int y) {
long s = (long)x - (long)y;
if (s < Integer.MIN_VALUE || s > Integer.MAX_VALUE) {
throw new ArithmeticException("overflow: subtract");
}
return (int)s;
}
}
</source>
Subtract two long integers, checking for overflow.
<source lang="java">
import java.math.BigDecimal; /*
* Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. * * */
public class Main {
/** * Subtract two long integers, checking for overflow. * * @param a first value * @param b second value * @return the differencea-b
* @throws ArithmeticException if the result can not be represented as an * long * @since 1.2 */ public static long subAndCheck(long a, long b) { long ret; String msg = "overflow: subtract"; if (b == Long.MIN_VALUE) { if (a < 0) { ret = a - b; } else { throw new ArithmeticException(msg); } } else { // use additive inverse ret = addAndCheck(a, -b, msg); } return ret; } /** * Add two long integers, checking for overflow. * * @param a an addend * @param b an addend * @param msg the message to use for any thrown exception. * @return the suma+b
* @throws ArithmeticException if the result can not be represented as an * long * @since 1.2 */ private static long addAndCheck(long a, long b, String msg) { long ret; if (a > b) { // use symmetry to reduce boundry cases ret = addAndCheck(b, a, msg); } else { // assert a <= b if (a < 0) { if (b < 0) { // check for negative overflow if (Long.MIN_VALUE - b <= a) { ret = a + b; } else { throw new ArithmeticException(msg); } } else { // oppisite sign addition is always safe ret = a + b; } } else { // assert a >= 0 // assert b >= 0 // check for positive overflow if (a <= Long.MAX_VALUE - b) { ret = a + b; } else { throw new ArithmeticException(msg); } } } return ret; }
}
</source>