无法获取textview以在android上显示用户输出

Question

我正在尝试创建一个基本的应用程序来获取用户的名字（输入）并显示其名称反转（输出）。但是，我似乎无法获得此代码来显示我想要的输出。我刚刚来到Android。如何在用户输出中显示字符串？

XML：

    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        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=".Main" >

    <Button
        android:id="@+id/reverse"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="166dp"
        android:text="@string/reverse" />

    <TextView
        android:id="@+id/desc"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="34dp"
        android:text="@string/desc"
        android:textAppearance="?
        android:attr/textAppearanceSmall" />

    <EditText
        android:id="@+id/name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/desc"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="48dp"
        android:ems="10" 
        android:inputType="text">

        <requestFocus />
    </EditText>

    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/name"
        android:layout_alignTop="@+id/reverse"
        android:layout_marginTop="67dp"
        android:text="@string/reversed"
        android:textAppearance="?
android:attr/textAppearanceSmall" />

    <TextView
        android:id="@+id/displayName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/reverse"
        android:layout_below="@+id/textView1"
        android:layout_marginTop="46dp"
        android:text="@string/medium_text"
        android:textAppearance="?android:attr/textAppearanceMedium" />

</RelativeLayout>

爪哇：

    package com.example.basicapp;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class Main extends Activity {

    Button reverse;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    public class Reverser extends android.app.Activity {
        TextView displayed = (TextView)findViewById(R.id.displayName);
        EditText nametext = (EditText)findViewById(R.id.name);
        String namestring = nametext.getText().toString();


        public void onClickListener() {

            reverse.setOnClickListener(new View.OnClickListener() {

                @Override
                public void onClick(View v) {
                    // TODO Auto-generated method stub

                    String reverse = new StringBuffer(namestring).reverse().toString();
                    String dr = reverse;
                    displayed.setText(dr);

                }
            });


        }

    }

}

谢谢。

Answer 1

public class Main extends Activity {

    Button reverse;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        TextView displayed = (TextView)findViewById(R.id.displayName);
        EditText nametext = (EditText)findViewById(R.id.name);
        String namestring = nametext.getText().toString();

        reverse=(Button)findViewById(R.id.reverse);//assuming you have button with id reverse

            reverse.setOnClickListener(new View.OnClickListener() {

                @Override
                public void onClick(View v) {
                    // TODO Auto-generated method stub

                    String reverse = new StringBuffer(namestring).reverse().toString();
                    String dr = reverse;
                    displayed.setText(dr);

                }
            });


    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

}