Question

我正在从斯坦福大学在线学习Java来制作一个简单的android项目。它需要制作一个简单的购物清单。

要求：当用户点击时当用户点击“添加项目”时，EditText中当前的任何内容都应添加到购物列表的底部，当用户点击＆＃34;清除列表＆＃34; ，你应该清除TextView的内容。

错误：当用户点击按钮时，我在向TextView添加项目时遇到了困难。

很难描述这个错误所以我把我项目的图片放在这里：

该项应该如下图所示：

如果有人能说出我的错误是什么以及我应该做什么，那就太好了，谢谢

以下是我的代码：

package com.stanford.ca108.shoppinglist;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }
    public void add(View view){
        TextView textView = (TextView)findViewById(R.id.textoutput);
        EditText edit = (EditText)findViewById(R.id.input);
        String a = edit.getText().toString();
        textView.append(a);
    }

    public void cleantext(View view){
        TextView textView = (TextView)findViewById(R.id.textoutput);
        textView.setText(" ");
    }
}

<?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:orientation="vertical"
    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.stanford.ca108.shoppinglist.MainActivity">

    <TextView
        android:id="@+id/textoutput"
        android:layout_width="match_parent"
        android:layout_height="350dp"
        android:textSize="20sp"
        android:text="Please List your items" />
    <EditText
        android:id="@+id/input"
        android:layout_above="@+id/bgroup"
        android:hint=" "
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
    <LinearLayout
        android:id="@+id/bgroup"
        android:layout_alignParentBottom="true"
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <Button
            android:text = "additem"
            android:layout_weight="1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:onClick="add"
            />
        <Button
            android:text = "clear list"
            android:layout_weight="1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:onClick="cleantext"
            />

        </LinearLayout>
</RelativeLayout>

Answer 1

//XML layout in the propertise of the Additem button

 android:onClick="additem"

// in Java Class


//set an onclick event listener for the Additem Button


public void additem(View view) {

    String itme1 = editview1.getText.toString;
    String itme2 = editview2.getText.toString;
    String itme3 = editview3.getText.toString;

    String TotalItem = item1+"\n"+item2+"\n"+item3;

    ShoplistTextView.setText(TotalItem);

    // this would trigger the method that would set all edittext to be //empty is the cart has been filled after 
    //pressing the additem button

    checkifShoplistIsNotEmpty();

}

public void checkifShoplistIsNotEmpty(){
    String check =cartTextView.getText.toString;
    if (!check.isEmpty()){
        editview1.setText("");
        editview2.setText("");
        editview3.setText("");
    }

Android Textview EditText错误

1 个答案: