Question

I am new to Android. I am trying to get input from the EditText and displaying it in TextView with the help of button. When I click the button nothing happens. Please help, here is my MainActivity.java code –

package com.example.addname;

import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends Activity {

    Button b1;
    TextView v1;
    EditText t1;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        b1 = (Button) findViewById(R.id.button1);
        t1 = (EditText) findViewById(R.id.editText1);
        v1 = (TextView) findViewById(R.id.textView1);

        b1.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                if(t1.getText().toString()=="")
                {

                    v1.setText(t1.getText().toString());
                }

            }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }

}

and here is my activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity" >

    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        android:text="@string/hello_world" />

    <EditText
        android:id="@+id/editText1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentRight="true"
        android:layout_alignParentTop="true"
        android:layout_marginTop="25dp"
        android:ems="10" >

        <requestFocus />
    </EditText>

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignRight="@+id/textView1"
        android:layout_below="@+id/editText1"
        android:layout_marginTop="48dp"
        android:text="Button" />

</RelativeLayout>

Answer 1

I’d recommend comparing strings with .equals() since Objects compared with == usually fails (== compares references, not Object content).

if(t1.getText().toString().equals("")))

in your case though,since you’re comparing an empty String, you can also use

if (t1.getText().toString().length == 0)

Then note that once you set the text, you’re setting v1‘s text to an empty string since your logic indicates that only upon an empty string you set v1‘s text. So I’d recommend getting rid of the if altogether:

@Override
public void onClick(View arg0) {
     v1.setText(t1.getText().toString());
}