我创建了一个简单的应用程序,用户输入他们的姓名和分数(只能是整数),然后通过单击按钮,它应该将这两个 EditText 框中的数据打印到日志中。问题是我的名称为 Null,分数为零。
//主要
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Button;
import android.widget.EditText;
public class MainActivity extends AppCompatActivity {
Button SaveDataButton;
EditText TextName, TextScore;
String Name;
int Score;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
SaveDataButton = (Button) findViewById(R.id.button);
TextName = (EditText) findViewById(R.id.editText1);
TextScore = (EditText) findViewById(R.id.editText2);
Name = TextName.getText().toString();
Score = Integer.parseInt(TextScore.getText().toString());
}
});
}
public void SaveDataOnClick (View view){
System.out.println(Name);
System.out.println(Score);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
//布局
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
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"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
tools:context="com.example.capstoneproject.module08courseproject_datastorage.MainActivity"
tools:showIn="@layout/activity_main">
<LinearLayout
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_below="@+id/textView3"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_marginTop="31dp"
android:weightSum="1">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceMedium"
android:text="Name"
android:id="@+id/textView" />
<EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/editText1"
android:layout_gravity="center_horizontal" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceMedium"
android:text="Score"
android:id="@+id/textView2" />
<EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/editText2"
android:layout_gravity="center_horizontal" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Save Data"
android:id="@+id/button"
android:layout_gravity="center_horizontal"
android:onClick="SaveDataOnClick" />
</LinearLayout>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:text="Name and Score Data Storage"
android:id="@+id/textView3"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true" />
</RelativeLayout>
//输出
11-29 22:07:01.846 3192-3192/? I/System.out: null
11-29 22:07:01.846 3192-3192/? I/System.out: 0
最佳答案
编辑,因为我错过了这样一个事实:您将匿名 onClickListener 中的小部件连接到您的 FloatingActionButton。进行以下更改来修复它:
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
// remove all the widget stuff and move it outside
}
});
SaveDataButton = (Button) findViewById(R.id.button);
TextName = (EditText) findViewById(R.id.editText1);
TextScore = (EditText) findViewById(R.id.editText2);
//Name = TextName.getText().toString();
//Score = Integer.parseInt(TextScore.getText().toString());
}
您编写的方式是,只有单击 float 操作按钮( Material 设计应用程序右下角的圆形按钮)时,才会执行上面的最后 5 行代码。我认为这不是您的预期行为。相反,您希望获取小部件引用并在 Activity 管理器调用 onCreate()
时保留它们。
我注释掉了最后两行,因为此时两个编辑文本中的值为空。这对于名称来说毫无用处,并且会导致分数出现数字格式异常(无法将 null 转换为数字)。
最后,我认为您希望在用户单击“SAVE DATA”按钮时获取实际值,因此请修改您的 SaveDataOnClick
方法。请记住,每次单击/点击按钮时都会调用此方法,因此它将获取编辑文本字段中的当前值。像这样的事情:
public void SaveDataOnClick (View view){
Name = TextName.getText().toString();
Score = Integer.parseInt(TextScore.getText().toString());
System.out.println(Name);
System.out.println(Score);
}
我进行了这些更改,这是我的日志输出:
11-29 22:44:22.696 20997-20997/? I/System.out: bobby
11-29 22:44:22.696 20997-20997/? I/System.out: 123
关于java - Android Studio 打印 EditText 返回 null,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/33990903/