java - Android：如何从输入字段中获取字符串值？

Question

我对 Android 很陌生，我一直坚持尝试从材料 inputField 组件中获取值字符串几个小时。

总而言之，我有一个单击并打开一个对话框的按钮，在对话框上有一个 inputField 和按钮。该按钮将使用 TextToSpeech 读出 inputField 所说的内容。

我相信这就是您从材料组件中获取字符串的方式（来源：http ://charmndroid.blogspot.com/2015/06/how-to-use-textinputlayout-in-android.html ）

除了从 inputField 中提取字符串值外，一切正常。如果我只注释掉，一切正常。包括语音方法（我尝试使用静态字符串并且它有效）。

你能帮我解决这个问题吗？

我得到的错误：

2020-10-23 01:00:56.610 12012-12012/com.example.mint_anroidapp E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.mint_anroidapp, PID: 31408
    java.lang.IllegalStateException: Could not execute method for android:onClick
        at android.view.View$DeclaredOnClickListener.onClick(View.java:5979)
        at android.view.View.performClick(View.java:7125)
        at com.google.android.material.button.MaterialButton.performClick(MaterialButton.java:992)
        at android.view.View.performClickInternal(View.java:7102)
        at android.view.View.access$3500(View.java:801)
        at android.view.View$PerformClick.run(View.java:27336)
        at android.os.Handler.handleCallback(Handler.java:883)
        at android.os.Handler.dispatchMessage(Handler.java:100)
        at android.os.Looper.loop(Looper.java:214)
        at android.app.ActivityThread.main(ActivityThread.java:7356)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)
     Caused by: java.lang.reflect.InvocationTargetException
        at java.lang.reflect.Method.invoke(Native Method)
        at android.view.View$DeclaredOnClickListener.onClick(View.java:5974)
        at android.view.View.performClick(View.java:7125) 
        at com.google.android.material.button.MaterialButton.performClick(MaterialButton.java:992) 
        at android.view.View.performClickInternal(View.java:7102) 
        at android.view.View.access$3500(View.java:801) 
        at android.view.View$PerformClick.run(View.java:27336) 
        at android.os.Handler.handleCallback(Handler.java:883) 
        at android.os.Handler.dispatchMessage(Handler.java:100) 
        at android.os.Looper.loop(Looper.java:214) 
        at android.app.ActivityThread.main(ActivityThread.java:7356) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930) 
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.widget.EditText com.google.android.material.textfield.TextInputLayout.getEditText()' on a null object reference
        at com.example.mint_anroidapp.MainActivity.speak(MainActivity.java:49)
        at java.lang.reflect.Method.invoke(Native Method) 
        at android.view.View$DeclaredOnClickListener.onClick(View.java:5974) 
        at android.view.View.performClick(View.java:7125) 
        at com.google.android.material.button.MaterialButton.performClick(MaterialButton.java:992) 
        at android.view.View.performClickInternal(View.java:7102) 
        at android.view.View.access$3500(View.java:801) 
        at android.view.View$PerformClick.run(View.java:27336) 
        at android.os.Handler.handleCallback(Handler.java:883) 
        at android.os.Handler.dispatchMessage(Handler.java:100) 
        at android.os.Looper.loop(Looper.java:214) 
        at android.app.ActivityThread.main(ActivityThread.java:7356) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930) 

MainActivity.java

public class MainActivity extends AppCompatActivity {

    private TextToSpeech text_to_speech;
    private TextInputLayout one_voice;


    Dialog myDialog;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        one_voice = (TextInputLayout) findViewById(R.id.command_one_voice);

        myDialog = new Dialog(this);

        text_to_speech = new TextToSpeech(this, new TextToSpeech.OnInitListener() {
            @Override
            public void onInit(int status) {
                if(status != TextToSpeech.ERROR) {
                    text_to_speech.setLanguage(Locale.CANADA);
                }
            }
        });
    }

    public void speak(View v) {
        String to_speak = one_voice.getEditText().getText().toString();
        text_to_speech.speak(to_speak, TextToSpeech.QUEUE_FLUSH, null);
    }

    public void OneShowPopup(View v) {
        TextView text_close;
        Button btnFollow = (Button) myDialog.findViewById(R.id.one_save_button);
        myDialog.setContentView(R.layout.command_one);
        text_close =(TextView) myDialog.findViewById(R.id.text_close);
        text_close.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                myDialog.dismiss();
            }
        });
        myDialog.getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));
        myDialog.show();
    }

command_one.xml

           <com.google.android.material.textfield.TextInputLayout
                android:id="@+id/command_one_voice"
                android:layout_marginTop="10dp"
                android:layout_marginBottom="10dp"
                android:layout_width="250dp"
                android:layout_height="wrap_content"
                android:layout_gravity="center"
                android:hint="@string/text">

                <com.google.android.material.textfield.TextInputEditText
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content" />

            </com.google.android.material.textfield.TextInputLayout>

         <com.google.android.material.button.MaterialButton
                    android:id="@+id/one_play_button"
                    android:onClick="speak"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_marginEnd="8dp"
                    android:layout_marginRight="8dp"
                    android:text="@string/play"
                    style="?attr/borderlessButtonStyle" />

MainActivity.xml

<com.google.android.material.button.MaterialButton
            android:onClick="OneShowPopup"
            android:id="@+id/command_one"
            android:layout_width="140dp"
            android:layout_height="100dp"
            android:padding="5dp"
            app:icon="@drawable/checked"
            android:textColor="#ffffff"
            android:text="Title 1"
            android:layout_marginRight="30dp"
            app:backgroundTint="#2BC9AF"
            app:iconGravity="textStart" />

标签： javaandroid

Answer 1

one_voice = (TextInputLayout) findViewById(R.id.command_one_voice);

您尝试在活动布局 ( MainActivity.xml) 中查找视图，但它位于对话框布局 ( command_one.xml) 中。你应该这样做：

 one_voice = (TextInputLayout) myDialog.findViewById(R.id.command_one_voice);

但只有在您启动此对话框之后。