java - 使用两个 Activity [ANDROID] 显示消息输出的问题

Question

我正在尝试使用两个 Activity 在 Android 中连接字符串。每次我输入两个字符串并点击按钮运行应用程序时，模拟器都会崩溃。你能帮我找到我在这里做错了什么吗？我的代码和错误如下。

Main Activity (Activity 1)

package com.example.tristan.a1p1n1;

import android.content.Intent;
import android.net.Uri;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;

public class MainActivity extends AppCompatActivity {


    public final static String EXTRA_MESSAGE = "com.example.tristan.a1p1n1.MESSAGE";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        // ATTENTION: This was auto-generated to implement the App Indexing API.
        // See https://g.co/AppIndexing/AndroidStudio for more information.
        client = new GoogleApiClient.Builder(this).addApi(AppIndex.API).build();
    }

    public void sendMessage(View view) {
        Intent intent = new Intent(this, DICS.class);
        EditText editText = (EditText) findViewById(R.id.editText);
        EditText editText2 = (EditText) findViewById(R.id.editText2);
        String message = editText.getText().toString() + editText2.getText().toString();
        intent.putExtra(EXTRA_MESSAGE, message);
        startActivity(intent);

    }}

DICS (Activity 2)

package com.example.tristan.a1p1n1;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.TextView;

/**
 * Created by Tristan on 2/11/2017.
 */
public class DICS extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.dics);

        //TextView mTextView = (TextView)findViewById(R.id.textView2);
       // mTextView.setText(getIntent().getStringExtra("message"))
    }
}

My Error Message:

E/AndroidRuntime: FATAL EXCEPTION: main
              Process: com.example.tristan.a1p1n1, PID: 3082
              java.lang.IllegalStateException: Could not execute method for android:onClick
                  at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:293)
                  at android.view.View.performClick(View.java:5610)
                  at android.view.View$PerformClick.run(View.java:22265)
                  at android.os.Handler.handleCallback(Handler.java:751)
                  at android.os.Handler.dispatchMessage(Handler.java:95)
                  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$MethodAndArgsCaller.run(ZygoteInit.java:865)
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)
               Caused by: java.lang.reflect.InvocationTargetException
                  at java.lang.reflect.Method.invoke(Native Method)
                  at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288)
                  at android.view.View.performClick(View.java:5610) 
                  at android.view.View$PerformClick.run(View.java:22265) 
                  at android.os.Handler.handleCallback(Handler.java:751) 
                  at android.os.Handler.dispatchMessage(Handler.java:95) 
                  at android.os.Looper.loop(Looper.java:154) 
                  at android.app.ActivityThread.main(ActivityThread.java:6077) 
                  at java.lang.reflect.Method.invoke(Native Method) 
                  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865) 
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755) 
               Caused by: android.content.ActivityNotFoundException: Unable to find explicit activity class {com.example.tristan.a1p1n1/com.example.tristan.a1p1n1.DICS}; have you declared this activity in your AndroidManifest.xml?
                  at android.app.Instrumentation.checkStartActivityResult(Instrumentation.java:1805)
                  at android.app.Instrumentation.execStartActivity(Instrumentation.java:1523)
                  at android.app.Activity.startActivityForResult(Activity.java:4224)
                  at android.support.v4.app.BaseFragmentActivityJB.startActivityForResult(BaseFragmentActivityJB.java:50)
                  at android.support.v4.app.FragmentActivity.startActivityForResult(FragmentActivity.java:79)
                  at android.app.Activity.startActivityForResult(Activity.java:4183)
                  at android.support.v4.app.FragmentActivity.startActivityForResult(FragmentActivity.java:859)
                  at android.app.Activity.startActivity(Activity.java:4507)
                  at android.app.Activity.startActivity(Activity.java:4475)
                  at com.example.tristan.a1p1n1.MainActivity.sendMessage(MainActivity.java:41)
                  at java.lang.reflect.Method.invoke(Native Method) 
                  at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288) 
                  at android.view.View.performClick(View.java:5610) 
                  at android.view.View$PerformClick.run(View.java:22265) 
                  at android.os.Handler.handleCallback(Handler.java:751) 
                  at android.os.Handler.dispatchMessage(Handler.java:95) 
                  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:865) 
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755) 

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.tristan.a1p1n1.MainActivity">

    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:inputType="textPersonName"
        android:text="Enter a String"
        android:ems="10"
        android:layout_below="@+id/textView"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:id="@+id/editText" />

    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:inputType="textPersonName"
        android:text="Enter a String"
        android:ems="10"
        android:id="@+id/editText2"
        android:layout_below="@+id/editText"
        android:layout_alignRight="@+id/editText"
        android:layout_alignEnd="@+id/editText"
        android:layout_marginRight="11dp"
        android:layout_marginEnd="11dp"
        android:layout_marginTop="13dp" />

    <Button
        android:text="+"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/editText2"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_marginTop="23dp"
        android:id="@+id/button"
        android:onClick="sendMessage" />
</RelativeLayout>

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.tristan.a1p1n1">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity><!-- ATTENTION: This was auto-generated to add Google Play services to your project for
     App Indexing.  See https://g.co/AppIndexing/AndroidStudio for more information. -->
        <meta-data
            android:name="com.google.android.gms.version"
            android:value="@integer/google_play_services_version" />
    </application>

</manifest>

dics.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">


    <TextView
        android:text="TextView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/textView2" />
</LinearLayout>

Answer 1

您的按钮 Xml 应该是:

<Button
    android:text="+"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@+id/editText2"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true"
    android:layout_marginTop="23dp"
    android:id="@+id/button"
    android:onClick="sendMessage" />  //change here

试试这个:在您的 MainActivity 中

String message = editText.getText().toString() + editText2.getText().toString();
intent.putExtra("message", message);

现在在 Dics Activity 中:

  TextView mTextView = (TextView)findViewById(R.id.textView2);
  mTextView.setText(getIntent().getStringExtra("message")); //the key ID should match