How can i edit the text of textview from .java?

Answer 1

To be more clear,

XML
<TextView
....
android:id="@+id/textView"
....
/>

JAVA
TextView tV = (TextView) findViewById(R.id.textView);
tV.setText("YOUR_TEXT_HERE");

Answer 2

TextView text1 = (TextView) findViewById(R.id.text1);
text1.setText("Hello");