DivZero
Division by integer literal zero

Severity
ERROR
Has Fix?
REQUIRES_HUMAN_ATTENTION

Alternate names: divzero

The problem

This code will cause a runtime arithmetic exception if it is executed.

Suppression

Suppress false positives by adding the suppression annotation @SuppressWarnings("DivZero") to the enclosing element.


Positive examples

DivZeroPositiveCases.java

/*
* Copyright 2013 The Error Prone Authors.
*
* Licensed 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.
*/


package com.google.errorprone.bugpatterns.testdata;

/** @author cushon@google.com (Liam Miller-Cushon) */
public class DivZeroPositiveCases {

public static void main(String[] args) {
new DivZeroPositiveCases();
}

static int staticOne = 0;

// BUG: Diagnostic contains: DivZero
static int staticTwo = staticOne / 0;

// BUG: Diagnostic contains: DivZero
static int staticThree = (staticTwo / 0);

int fieldOne;

// BUG: Diagnostic contains: DivZero
int fieldTwo = fieldOne / 0;

// BUG: Diagnostic contains: DivZero
int fieldThree = (fieldTwo /= 0);

int f() {
return 42;
}

void method(final int a, double b, boolean flag) {
int x;
double y;

// BUG: Diagnostic contains: throw new ArithmeticException
x = a / 0;

// BUG: Diagnostic contains: throw new ArithmeticException
x /= 0;

x =
((((a / a) / (a / a)) / ((a / a) / (a / a))) / (((a / a) / (a / a)) / ((a / a) / (a / a))))
/
// BUG: Diagnostic contains: zero
((((a / a) / (a / a)) / ((a / 0) / (a / a)))
/ (((a / a) / (a / a)) / ((a / a) / (a / a))));

// BUG: Diagnostic contains: throw new ArithmeticException
x = flag ? a / 0 : 42;

// BUG: Diagnostic contains: throw new ArithmeticException
for (int i = 0; i < 10; i /= 0) {}

Object o =
new Object() {
// BUG: Diagnostic contains: throw new ArithmeticException
int x = a / 0;
};

// BUG: Diagnostic contains: throw new ArithmeticException
x = f() / 0;
}

// TODO(cushon): write a check for self-references via qualified names in field initializers,
// even if JLS 8.3.2.3 permits it.

// BUG: Diagnostic contains: DivZero
int selfRefField = this.selfRefField / 0;

// BUG: Diagnostic contains: DivZero
static int staticSelfRefField = DivZeroPositiveCases.staticSelfRefField / 0;
}

Negative examples

DivZeroNegativeCases.java

/*
* Copyright 2013 The Error Prone Authors.
*
* Licensed 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.
*/


package com.google.errorprone.bugpatterns.testdata;

/** @author cushon@google.com (Liam Miller-Cushon) */
public class DivZeroNegativeCases {

void method(int a) {
double y = (double) a / 0.0;
}
}