Division in Java always results in zero (0)? [duplicate]

问题

This question already has an answer here:

Double value returns 0 [duplicate] 3 answers

The function below gets two values from sharedpreferences, weight and height, and I use these to calculate the BMI, When I print the content of the values I get the values i have entered in the sharedprefs ( which is good) but then when i run a division operation on them, I always get 0 as a result.. Where is the error?

public int computeBMI(){
    SharedPreferences customSharedPreference = getSharedPreferences(
            \"myCustomSharedPrefs\", Activity.MODE_PRIVATE);

    String Height = customSharedPreference.getString(\"heightpref\", \"\");
    String Weight = customSharedPreference.getString(\"weightpref\", \"\");

    int weight = Integer.parseInt(Weight);
    int height = Integer.parseInt(Height);
    Toast.makeText(CalculationsActivity.this, Height+\" \"+ Weight , Toast.LENGTH_LONG).show();

    int bmi = weight/(height*height);
    return bmi;

}

回答1:

You're doing integer division.

You need to cast one operand to double.

回答2:

You are doing an integer division, cast the values to float and change the datatype of the variable bmi to float.

Like this:

float bmi = (float)weight/(float)(height*height);

You should also change the return type of your method public int computeBMI() to float.

I recommend you to read this stackoverflow question.

Here you have a list of the Primitive Data Types in Java with its full description.

Hope it helps!

回答3:

Because bmi is an integer. Either declare bmi or Weight, Height as floating point numbers. When you use integers in a division, you will get integer division. When you use doubles/floats, you will get floating point division

来源：https://stackoverflow.com/questions/10455677/division-in-java-always-results-in-zero-0

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java

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division