Question

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How do I compare strings in Java?

even whel length is 0 and flag9 is null only else part is executed.can someone help me

Log.d(TAG, "flag8 "+ getIntent().getExtras().getString("flag").length());
Log.d(TAG, "flag9 "+ getIntent().getExtras().getString("flag"));
if( getIntent().getExtras().getString("flag")=="0"   ||getIntent().getExtras().getString("flag").length()==0)
{
 Log.d(TAG, "hidebeta "+ getIntent().getExtras().getString("flag"));
            beta.putExtra("beta", "hidebeta");
            flag=1;
            beta.putExtra("flag", "1");
                }
else {
    beta.putExtra("beta","showbeta");
    Log.d(TAG, "showbeta "+ getIntent().getExtras().getString("flag"));
    flag=0;
    beta.putExtra("flag","0");
                }

Answer 1

In Java you cannot use == to compare Strings, you must use:

if(string.equals("example"))

So let’s use equals() in your conditional and optimize it:

String flag = getIntent().getStringExtra("flag");
if(flag.equals("0") || flag.length()==0)

(Also you ought to be safe and check if getIntent() and flag are not null before trying to access them.)

Read How do I compare strings in Java? or the documentation on Comparing Strings for more information.