<= && >= Java/Android Operators

Question

Im having a problem on this block of code. It always go on the "You're outside of the museum or Check your position again" toast :/ what do you think is the problem? Here is the code:

    x3 = x3 * -1; //for example is 187
    y3 = y3 * -1;//for example is 698

    ImageView img = (ImageView) findViewById(R.id.imageView1);

    if(((x3 <= 150) && (x3 >= 170)) && ((y3 <= 680) && (y3 >= 725))){
        img.setImageResource(R.drawable.map_1_full_lite);
        Toast.makeText(getBaseContext(), "You're currently on Section 1", Toast.LENGTH_LONG).show();
        currentSection = "sect_1";
    }else if(((x3 <= 170) && (x3 >= 195)) && ((y3 <= 690) && (y3 >= 715))){
        img.setImageResource(R.drawable.map_2_full_lite);
        Toast.makeText(getBaseContext(), "You're currently on Section 2", Toast.LENGTH_LONG).show(); //this suppost to be the output
        currentSection = "sect_2";
    }else if(((x3 <= 200) && (x3 >= 230)) && ((y3 <= 680) && (y3 >= 720))){
        img.setImageResource(R.drawable.map_3_full_lite);
        Toast.makeText(getBaseContext(), "You're currently on Section 3", Toast.LENGTH_LONG).show();
        currentSection = "sect_3";
    }else if(((x3 <= 190) && (x3 >= 220)) && ((y3 <= 675) && (y3 >= 710))){
        img.setImageResource(R.drawable.map_4_full_lite);
        Toast.makeText(getBaseContext(), "You're currently on Section 4", Toast.LENGTH_LONG).show();
        currentSection = "sect_4";
    }else if(((x3 <= 175) && (x3 >= 219)) && ((y3 <= 710) && (y3 >= 745))){
        img.setImageResource(R.drawable.map_5_full_lite);
        Toast.makeText(getBaseContext(), "You're currently on Section 5", Toast.LENGTH_LONG).show();
        currentSection = "sect_5";
    }else if(((x3 <= 155) && (x3 >= 165)) && ((y3 <= 715) && (y3 >= 735))){
        img.setImageResource(R.drawable.map_6_full_lite);
        Toast.makeText(getBaseContext(), "You're currently on Section 6", Toast.LENGTH_LONG).show();
        currentSection = "sect_6";
    }else{
        Toast.makeText(getBaseContext(), "You're outside of the museum or Check your postion again", Toast.LENGTH_LONG).show();
    }

x3 cannot be both less than 150 and greater than 170 simultaneously. — Oliver Charlesworth
– Oliver Charlesworth, Commented Jan 28, 2013 at 8:43
I would also like to mention that the program doesn't say "You're outside of the museum or Check your position again", ever. — Mr Lister
– Mr Lister, Commented Jan 28, 2013 at 8:53

Peter Lawrey · Accepted Answer · 2013-01-28 08:43:24Z

4

This is impossible

(x3 <= 150) && (x3 >= 170)

as is

(x3 <= 170) && (x3 >= 195)

x3 cannot be less than or equal to 150 AND greater than or equal to 170. I suspect you intended something like this

(150 <= x3) && (x3 <= 170)

and

(170 <= x3) && (x3 <= 195)

answered Jan 28, 2013 at 8:43

Peter Lawrey

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6 Comments

Dan Over a year ago

You mean || in your last statement, didn't you?

Peter Lawrey Over a year ago

Corrected it. I meant x3 is between [150, 170] I assume he has tiles the user can click on.

oshongo Over a year ago

the logic is that if the x3 = 187(for example) is between of 150 x to 170 x and y3 = 693(for example) is between of 690 y and 715 y, then that coordinate is on that section.. something like that :O

Peter Lawrey Over a year ago

How is 187 between 150 and 170?

Peter Lawrey Over a year ago

I would write this as 150 <= x3 && x3 <= 170 && 680 <= y3 && y3 <= 725

|

andr · Accepted Answer · 2013-01-28 08:46:49Z

You have conditions that are always false. Just consider:

((x3 <= 155) && (x3 >= 165)) && ((y3 <= 715) && (y3 >= 735))

the && operator is AND meaning both of the conditions on the sides of that operator must be true for the whole expression to be true. Now it is not hard to find out that for any value of x3 the condition (x3 <= 155) && (x3 >= 165) is false. Thus the condition can never be met.

Every branch of your if has that property, so in the end the else branch is chosen.

I think you have mixed the <= (less than or equal) and >= (more than or equal) operators. All the values, for example x3, should be in some range (i.e. room boundary coordinates), like in the mentioned case x3 should probably be in the range (x3 >= 155) && (x3 <= 165) (note reversed operators).

assylias · Accepted Answer · 2013-01-28 09:03:37Z

1

That's because your statements such as

(x3 <= 150) && (x3 >= 170)

can never be true.

Did you mean this?

(x3 <= 150) || (x3 >= 170)

edited Jan 28, 2013 at 9:03

assylias

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answered Jan 28, 2013 at 8:43

Dan

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