Min-SDKVersion= "8"
SDKVersion = "18"


Cole isso na sua MainActivity.java

EditText nome,idade;
	private RadioGroup sexo;
	private RadioButton aux;
	
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);

	 nome = (EditText) findViewById(R.id.editText1);
     idade = (EditText) findViewById(R.id.editText2);
     sexo = (RadioGroup) findViewById(R.id.radioGroup1);
      
		Button button1= (Button) findViewById(R.id.button1);
		
		button1.setOnClickListener(new View.OnClickListener() {
			
			@Override
			public void onClick(View arg0) {
				// TODO Auto-generated method stub
				String test = nome.getText().toString();
				String test1 = idade.getText().toString();
				// test2 = sexo.getCheckedRadioButtonId().getText();
				RadioButton selectRadio = (RadioButton) findViewById(sexo.getCheckedRadioButtonId());
				String radiotest = selectRadio.getText().toString();
				
			    
				
				AlertDialog.Builder dialogo = new AlertDialog.Builder(MainActivity.this);
				dialogo.setTitle("Relatório:");
				dialogo.setMessage("Nome: " +  test + "\nIdade: " + test1 + "\nSexo: " + radiotest);
				dialogo.setNeutralButton("ok",null);
				dialogo.show();
			}
		});
		
		
	}

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

Em seguida adicione em seu activity_maint.xml (res/layout/activity_main.xml)

 <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:text="Informe seu nome:"
        android:textAppearance="?android:attr/textAppearanceLarge" />

    <EditText
        android:id="@+id/editText1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/textView1"
        android:layout_below="@+id/textView1"
        android:ems="10" >

        <requestFocus />
    </EditText>

    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/editText1"
        android:layout_below="@+id/editText1"
        android:layout_marginTop="17dp"
        android:text="Informe sua idade:"
        android:textAppearance="?android:attr/textAppearanceLarge" />

    <EditText
        android:id="@+id/editText2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/textView2"
        android:layout_below="@+id/textView2"
        android:ems="10" />

    <TextView
        android:id="@+id/textView3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/editText2"
        android:layout_below="@+id/editText2"
        android:layout_marginTop="14dp"
        android:text="Informe seu sexo:"
        android:textAppearance="?android:attr/textAppearanceLarge" />

    <RadioGroup
        android:id="@+id/radioGroup1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_below="@+id/textView3" >

        <RadioButton
            android:id="@+id/radio0"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:checked="true"
            android:text="Masculino" />

        <RadioButton
            android:id="@+id/radio1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Feminino" />
    </RadioGroup>

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignRight="@+id/textView3"
        android:layout_below="@+id/radioGroup1"
        android:layout_marginTop="28dp"
        android:text="Relatorio" />

Foto Ilustrativa do Aplicativo Rodando

Ta errado isso ai cara seu sexo é Feminino.

Mas ficou legalzinho até.