Android Studio 新建编辑条 点击按钮显示控件中的内容

package com.example.zf.myapplication;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    private EditText editText;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Log.d("HelloWorldActivity","onCreate execute");
        Button button = (Button) findViewById(R.id.button);
        editText = (EditText) findViewById(R.id.edit_text);
        button.setOnClickListener(this);
        }

        @Override
        public void onClick(View v) {
            switch (v.getId()){
                case R.id.button:
                    String inputText = editText.getText().toString();
                    Toast.makeText(MainActivity.this,inputText,Toast.LENGTH_SHORT).show();
                    break;
                    default:
                        break;

            }

        }
}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">
    <TextView
        android:id="@+id/text_view"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:textSize="24sp"
        android:textColor="#00ff00"
        android:text="This is TextView"/>

    <Button
        android:id="@+id/button"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Button"
        android:textAllCaps="false"/>

    <EditText
        android:id="@+id/edit_text"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Type something here"
        android:maxLines="2"
        />
    </LinearLayout>