putextra和getextra不将字符串传递给下一个活动

Question

I have three activities A,B and C

In my B activity I have one imageview, when I get a String from activity A to B, the imageview should be visible.

When I get a String from activity C to B then the imageview should not be visible.

//From activity A
Intent iin= getIntent();
Bundle b = iin.getExtras();
//From Activity C
Intent i2=getIntent();
Bundle abcd=i2.getExtras();

if(b!=null)
{
    String j =(String) b.get("arrowvisi");

    Toast.makeText(getApplicationContext(), j, Toast.LENGTH_LONG).show();
    if(j==b.get("arrowvisi"))
    {
        img_back.setVisibility(View.VISIBLE);
        Toast.makeText(getApplicationContext(), "Operational arrow visible", Toast.LENGTH_LONG).show();

    }
    else
    {
        if(abcd!=null)
        {
            String jst =(String) abcd.get("arrow_val");
            if(jst==abcd.get("arrow_val"))
            {
                img_back.setVisibility(View.GONE);
                Toast.makeText(getApplicationContext(), "scan dispatch visble", Toast.LENGTH_LONG).show();
            }
            else
            {
                //img_back.setVisibility(View.GONE);

                System.out.println("from scan dispatch");
                Toast.makeText(getApplicationContext(), "scan dispatch not visible", Toast.LENGTH_LONG).show();
            }

        }


        Toast.makeText(getApplicationContext(), "Operational not visible", Toast.LENGTH_LONG).show();
    }

}

Answer 1

First of all,to compare strings in java,you need to use .equals

so change

 if(j==b.get("arrowvisi"))

to

 if(j.equals(b.getString("arrowvisi")))

and

if(jst==abcd.get("arrow_val"))

to

if(jst.equals(abcd.getString("arrow_val")))

And second,your condition always will be true,because you are comparing two equal values always,ie first getting value in jst and then comparing same value.

Edit : to resolve null pointer change

 String j =(String) b.get("arrowvisi");

to

 String j = b.getString("arrowvisi");

and

 String jst =(String) abcd.get("arrow_val");

to

 String jst =abcd.getString("arrow_val");

And post logcat exception.

Answer 2

Replace

String j = (String) b.get("arrowvisi");

with

String j = b.getString("arrowvisi");

and

String jst = (String) abcd.get("arrow_val");

with

String jst = abcd.getString("arrow_val");

also string comparison should be like

j.equals(b.getString("arrowvisi")) // change again

and

jst.equals(abcd.getString("arrow_val"))  // change again 

So, the final ans should be something like

//From activity A
Intent iin = getIntent();
Bundle b = iin.getExtras();

//From Activity C
Intent i2 = getIntent();
Bundle abcd = i2.getExtras();

if(b != null){
    String j = "String to check"; // Replace content inside "" with your string 
    Toast.makeText(getApplicationContext(), j, Toast.LENGTH_LONG).show();
    if(j.equals(b.getString("arrowvisi"))){
        img_back.setVisibility(View.VISIBLE);
        Toast.makeText(getApplicationContext(), "Operational arrow visible", Toast.LENGTH_LONG).show();
    }else{
        if(abcd != null){
            String jst = "String to check"; // Replace with string you want to check
            if(jst.equals(abcd.getString("arrow_val"))){
                img_back.setVisibility(View.GONE);
                    Toast.makeText(getApplicationContext(), "scan dispatch visble", Toast.LENGTH_LONG).show();
                }else{
                    //img_back.setVisibility(View.GONE);
                    System.out.println("from scan dispatch");
                    Toast.makeText(getApplicationContext(), "scan dispatch not visible", Toast.LENGTH_LONG).show();
                }
            }
            Toast.makeText(getApplicationContext(), "Operational not visible", Toast.LENGTH_LONG).show();
        }
    }

Also note that, doing something like

String jst = abcd.getString("arrow_val"));
if(jst.equals(abcd.getString("arrow_val"))) // this will be always true

this, will result in if statement being always true.

2 options :

1) Remove if statement because always true.

2) change String jst = "Some string to compare" (change this) and now compare jst with getString("arrow_val") using jst.equals(abcd.getString("arrow_val")) in your if loop

Answer 3

change this

String j = (String) b.get("arrowvisi");

with

String j = b.getString("arrowvisi");

and

String jst = (String) abcd.get("arrow_val");

with

String jst = abcd.getString("arrow_val");

also put this in bracket()

b.get("arrowvisi")
abcd.get("arrow_val")