Some of my code is not executing in android studios?

Question

In the program below used for an android app in android studios, When getPercent() from the second class(Main2Activity) is invoked, it always returns 999(the default value), and the,

ttper = .....;

statement from the main class in the onClick() is never executed. Is there any specific reason for this? Can you guys point it out please!

This is the main activity,

public class MainActivity extends AppCompatActivity {

float i1m,i2m,mm,atp,assp;
float ttper=999;
boolean b=false;
EditText i1,i2,model,assignment,attendence;
Button b1;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    final Context cont = this;
    final Intent intent = new Intent(cont, Main2Activity.class);

    b1=(Button)findViewById(R.id.button2);
    b1.setOnClickListener(new OnClickListener(){
        @Override
        public void onClick(View v) {
            //try {
            i1=(EditText)findViewById(R.id.int1);
            i2=(EditText)findViewById(R.id.int2);
            model=(EditText)findViewById(R.id.mod);
            assignment=(EditText)findViewById(R.id.assign);
            attendence=(EditText)findViewById(R.id.attend);

            i1m = Float.parseFloat(String.valueOf(i1.getText()));
            i2m = Float.parseFloat(i2.getText().toString());
            mm = Float.parseFloat(model.getText().toString());
            assp = Float.parseFloat(assignment.getText().toString());
            atp = Float.parseFloat(attendence.getText().toString());
            ttper = ((i1m / 10) + (i2m / 10) + ((mm / 100) * 15) + (assp) + ((atp >= 75.0f) ? ((atp - 75) / 5) : 0.0f));

            //setValues();
            startActivity(intent);
            //}
            //catch (Exception e) {
              //  Log.e("app crash",e.getMessage());
            //}
        }
    });
}
/*void setValues()
{
   /* i1m = Float.parseFloat(String.valueOf(i1.getText()));
    i2m = Float.parseFloat(i2.getText().toString());
    mm = Float.parseFloat(model.getText().toString());
    assp = Float.parseFloat(assignment.getText().toString());
    atp = Float.parseFloat(attendence.getText().toString());*/
}/*
float getPercent()
{
        //float ttper=50.0f;
        return ttper;
}
}

This is the second activity,

public class Main2Activity extends AppCompatActivity {

float tper=1.0f;
String str;
@Override
protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);

        TextView v1 = (TextView) findViewById(R.id.textView11);
        MainActivity m1 = new MainActivity();
       //m1.setValues();
        //try {
            str = String.valueOf(m1.getPercent()) + "%";
            v1.setText(str);
        //}
    //catch (Exception e) {
      //  Log.e("app crash",e.getMessage());
    //}
}

}

You should never use `new` to create an instance of an Activity class — OneCricketeer, Oct 05 '16 at 14:24

score 1 · Accepted Answer · edited May 23 '17 at 12:19

1

it can not work. If you create new MainActivity(), your ttper will be 999.

You should pass data between Activities in this way:

Put the new calculated ttper into Intent: intent.putExtra("ttper", ttper );
Then in MainActivity2 use getIntent().getFloatExtra("ttper", 999.0f);

edited May 23 '17 at 12:19

Community

1
1

answered Oct 05 '16 at 14:25

alex

8,904
6
49
75

Please flag the question as a duplicate – OneCricketeer Oct 05 '16 at 14:28

ig343 · Answer 2 · 2016-10-05T14:35:36.557

You have an instance of MainActivity which has a variable ttper. You modify that value. Then in another class Main2Activity you create a NEW instance of MainActivity and try to get that value, but ttper has the default value because this is a NEW instance and it hasn't been modified yet.

What you can do is defining ttper as static:

static float ttper=999;

You can even define your function getPercent() as static so you don't have to create a new instance of this class to get the value. You would just call MainActivity.getPercent().

For more information, read: https://docs.oracle.com/javase/tutorial/java/javaOO/classvars.html

Anyway, this is not the correct way of passing data from one activity to another. You should follow this guidelines: https://developer.android.com/training/basics/firstapp/starting-activity.html

learnt a new thing about static from you! I knew the definition but didnt know what i accualy does. Thanks! — Rishi Swethan, Oct 05 '16 at 17:03

score 0 · Answer 3 · answered Oct 05 '16 at 15:59

0

You should use extras on intents to pass data between activies.

answered Oct 05 '16 at 15:59

Filipe Gonçalves

181
3
16

Some of my code is not executing in android studios?

3 Answers3