Java Android Studio:添加两个不带按钮的数字
我正在使用Android Studio开发一个添加两个数字的程序。首先,我使用了一个按钮开始计算,但现在我不想再使用这个按钮了,所以我正在寻找一种实时添加两个数字的可能性。如果我更改一个数字,结果应该立即显示。你有什么建议吗? 这是我对按钮变体的代码: 新代码:Java Android Studio:添加两个不带按钮的数字,java,android,android-studio,calculation,Java,Android,Android Studio,Calculation,我正在使用Android Studio开发一个添加两个数字的程序。首先,我使用了一个按钮开始计算,但现在我不想再使用这个按钮了,所以我正在寻找一种实时添加两个数字的可能性。如果我更改一个数字,结果应该立即显示。你有什么建议吗? 这是我对按钮变体的代码: 新代码: public class MainActivity extends AppCompatActivity { EditText firstNumEditText, secondNumEditText; TextView
public class MainActivity extends AppCompatActivity {
EditText firstNumEditText, secondNumEditText;
TextView resultTextView;
class MyTextWatcher implements TextWatcher {
@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
}
@Override
public void afterTextChanged(Editable s) {
String second = secondNumEditText.getText().toString().trim();
String first = firstNumEditText.getText().toString().trim();
int num1 = Integer.parseInt(second);
int num2 = Integer.parseInt(first);
int result = num1 + num2;
resultTextView.setText(result + "");
}
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
firstNumEditText = (EditText) findViewById(R.id.firstNumEditText);
firstNumEditText.addTextChangedListener(new MyTextWatcher());
secondNumEditText = (EditText) findViewById(R.id.secondNumEditText);
secondNumEditText.addTextChangedListener(new MyTextWatcher());
resultTextView = (TextView) findViewById(R.id.resultTextView);
}
}
LogCat的输出:
java.lang.NumberFormatException: For input string: ""
at java.lang.Integer.parseInt(Integer.java:533)
at java.lang.Integer.parseInt(Integer.java:556)
at com.example.aufgabe2.MainActivity$MyTextWatcher.afterTextChanged(MainActivity.java:33)
at android.widget.TextView.sendAfterTextChanged(TextView.java:8202)
at android.widget.TextView$ChangeWatcher.afterTextChanged(TextView.java:10381)
at android.text.SpannableStringBuilder.sendAfterTextChanged(SpannableStringBuilder.java:1218)
at android.text.SpannableStringBuilder.replace(SpannableStringBuilder.java:579)
at android.text.SpannableStringBuilder.replace(SpannableStringBuilder.java:509)
at android.text.SpannableStringBuilder.replace(SpannableStringBuilder.java:508)
at android.text.method.NumberKeyListener.onKeyDown(NumberKeyListener.java:121)
at android.widget.TextView.doKeyDown(TextView.java:6284)
at android.widget.TextView.onKeyDown(TextView.java:6074)
at android.view.KeyEvent.dispatch(KeyEvent.java:2676)
at android.view.View.dispatchKeyEvent(View.java:9880)
at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1667)
at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1667)
at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1667)
at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1667)
at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1667)
at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1667)
at com.android.internal.policy.DecorView.superDispatchKeyEvent(DecorView.java:403)
at com.android.internal.policy.PhoneWindow.superDispatchKeyEvent(PhoneWindow.java:1800)
at androidx.core.view.KeyEventDispatcher.activitySuperDispatchKeyEventPre28(KeyEventDispatcher.java:130)
at androidx.core.view.KeyEventDispatcher.dispatchKeyEvent(KeyEventDispatcher.java:87)
at androidx.core.app.ComponentActivity.dispatchKeyEvent(ComponentActivity.java:126)
at androidx.appcompat.app.AppCompatActivity.dispatchKeyEvent(AppCompatActivity.java:535)
at androidx.appcompat.view.WindowCallbackWrapper.dispatchKeyEvent(WindowCallbackWrapper.java:59)
at androidx.appcompat.app.AppCompatDelegateImpl$AppCompatWindowCallback.dispatchKeyEvent(AppCompatDelegateImpl.java:2533)
at com.android.internal.policy.DecorView.dispatchKeyEvent(DecorView.java:317)
at android.view.ViewRootImpl$ViewPostImeInputStage.processKeyEvent(ViewRootImpl.java:4327)
at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:4298)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3849)
at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3902)
at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3868)
at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:3995)
at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3876)
at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:4052)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3849)
at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3902)
at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3868)
at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3876)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3849)
at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:6210)
at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:6184)
at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:6145)
at android.view.ViewRootImpl$ViewRootHandler.handleMessage(ViewRootImpl.java:3647)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
您可以在
EditText
上使用TextWatcher
来侦听文本更改事件,并执行添加或减号等操作。TextWatcher可以帮助您从EditText动态获取值:
- 我添加了一个内部类来实现TextWatcher
- 将对象从该内部类传递到
editText.AddContextChangedListener
- 我使用
从EditText获取结果并执行我的操作postertextchanged()
您可以通过将
addTextChangedListener
添加到editText
中来完成此操作
editText.addTextChangeListener(new TextWatcher() {
@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
// here you can extract the value from edit text and do the addition
}
@Override
public void afterTextChanged(Editable s) {
}
});
这回答了你的问题吗?谢谢,我会试试的!我不知道为什么,但现在节目还没开始。没有错误,但模拟手机表示应用程序一直停止。我在问题中添加了新代码。如果我犯了一个错误,我很抱歉,但我是Android新手:)@bfg没关系,我的朋友。只要在调用onCreate之前不要
findViewById
。另外,您将setConteView(R.layout.activity\u main)
两次,删除其中一个。我编辑了答案,更新了密码。现在应用程序启动了,但只要我想输入一个数字,应用程序就会停止。安卓工作室没有提到mistakes@bfg请提供Android Studio中LogCat的错误日志,以便我可以帮助您解决此问题。
editText.addTextChangeListener(new TextWatcher() {
@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
// here you can extract the value from edit text and do the addition
}
@Override
public void afterTextChanged(Editable s) {
}
});