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POHow can I read the spinners and get data from an edittext to a textview in consequence?
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copied!<p>I'd like to know where my code makes errors. this activity should be like a unit converter. there are two spinner to chose the unit, an edittest to insert the value and a textview to show the result. acrtually when i insert a value and press the button to convert it crush. can you help me? thank you and sorry for my english</p> <pre><code>public class lunghezze extends Activity implements OnClickListener { EditText et1; TextView tv1; Spinner spinner1,spinner2; Button btnAdd; String oper = ""; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.converter); Spinner spinner1 = (Spinner) findViewById(R.id.spinner1); Spinner spinner2 = (Spinner) findViewById(R.id.spinner2); ArrayAdapter<CharSequence> adapter1 = ArrayAdapter.createFromResource(this,R.array.lunghezza, android.R.layout.simple_spinner_item); adapter1.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); spinner1.setAdapter(adapter1); ArrayAdapter<CharSequence> adapter2 = ArrayAdapter.createFromResource(this,R.array.lunghezza, android.R.layout.simple_spinner_item); adapter2.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); spinner2.setAdapter(adapter2); // find the elements et1 = (EditText) findViewById(R.id.editText1); btnAdd = (Button) findViewById(R.id.button1); tv1 = (TextView) findViewById(R.id.textView4); // set a listener btnAdd.setOnClickListener(this); } @Override public void onClick(View v) { // TODO Auto-generated method stub double num1 = 0; double resdelta = 0; double res = 0; double resx2 = 0; if (TextUtils.isEmpty(et1.getText().toString())) { return; } String a = et1.getText().toString().trim(); num1 = a.isEmpty()? Double.NaN:Double.parseDouble(a); switch (v.getId()) { case R.id.button1: String s1 = spinner1.getSelectedItem().toString(); String s2 = spinner2.getSelectedItem().toString(); if (s1 + s2 == "IardeIarde"){ tv1.setText("" + num1); } else { } break; default: break; </code></pre> <p>and here's the logcat</p> <pre><code> 11-12 17:56:04.063: E/AndroidRuntime(1415): FATAL EXCEPTION: main 11-12 17:56:04.063: E/AndroidRuntime(1415): java.lang.NullPointerException 11-12 17:56:04.063: E/AndroidRuntime(1415): at com.example.easyphysics.lunghezze.onClick(lunghezze.java:91) 11-12 17:56:04.063: E/AndroidRuntime(1415): at android.view.View.performClick(View.java:4084) 11-12 17:56:04.063: E/AndroidRuntime(1415): at android.view.View$PerformClick.run(View.java:16966) 11-12 17:56:04.063: E/AndroidRuntime(1415): at android.os.Handler.handleCallback(Handler.java:615) 11-12 17:56:04.063: E/AndroidRuntime(1415): at android.os.Handler.dispatchMessage(Handler.java:92) 11-12 17:56:04.063: E/AndroidRuntime(1415): at android.os.Looper.loop(Looper.java:137) 11-12 17:56:04.063: E/AndroidRuntime(1415): at android.app.ActivityThread.main(ActivityThread.java:4745) 11-12 17:56:04.063: E/AndroidRuntime(1415): at java.lang.reflect.Method.invokeNative(Native Method) 11-12 17:56:04.063: E/AndroidRuntime(1415): at java.lang.reflect.Method.invoke(Method.java:511) 11-12 17:56:04.063: E/AndroidRuntime(1415): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786) 11-12 17:56:04.063: E/AndroidRuntime(1415): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 11-12 17:56:04.063: E/AndroidRuntime(1415): at dalvik.system.NativeStart.main(Native Method) </code></pre>

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