java - 如何处理从xml到Activity的点击

Question

我是 Android 新手，正在学习本教程:https://www.youtube.com/watch?v=qK0QNA0sMGc&t=2710s(印地语)

在我的MainActivity.java中:

当我尝试运行该应用程序时，它给出错误:

9 errors found
1 warning found
2 typos found

它要求我在末尾加一个分号
Log.i(tag:"this", msg:"clickbtn: 这是一条消息");
我已经放下了。

这是我的activity_main.xml:

谁能告诉我有哪些错误吗？

XML 代码:

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 
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"
tools:context=".MainActivity">

<TextView
    android:id="@+id/topText"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginTop="60dp"
    android:includeFontPadding="false"
    android:paddingTop="10dip"
    android:paddingBottom="10dip"
    android:text="Welcome to Shivam Travels"
    android:textAppearance="@style/TextAppearance.AppCompat.Body1"
    android:textSize="24sp"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_bias="0.504"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent" />

<EditText
    android:id="@+id/editText"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginTop="32dp"
    android:ems="10"
    android:hint="Enter your username"
    android:inputType="textPersonName"
    app:layout_constraintStart_toStartOf="@+id/topText"
    app:layout_constraintTop_toBottomOf="@+id/topText" />

<EditText
    android:id="@+id/editText2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginTop="32dp"
    android:ems="10"
    android:hint="Enter your password"
    android:inputType="textPassword"
    app:layout_constraintStart_toStartOf="@+id/editText"
    app:layout_constraintTop_toBottomOf="@+id/editText" />

<Button
    android:id="@+id/button"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginTop="28dp"
    android:onClick="clickbtn"
    android:text="Sign In"
    app:layout_constraintStart_toStartOf="@+id/checkBox"
    app:layout_constraintTop_toBottomOf="@+id/checkBox" />

<CheckBox
    android:id="@+id/checkBox"
    android:layout_width="176dp"
    android:layout_height="65dp"
    android:layout_marginTop="32dp"
    android:text="Remember me!"
    app:layout_constraintStart_toStartOf="@+id/editText2"
    app:layout_constraintTop_toBottomOf="@+id/editText2" />

Answer 1

用此代码替换您的代码

替换

Log.i(tag:"this", msg:"clickbtn: This is a message");

与

Log.i("This","This is a message");

下面是完整的代码 fragment

JAVA 文件

import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Toast;

public class MainTestActivity extends Activity {
    Context context;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        context = this;
        setContentView(R.layout.activity_main);
    }

    public void clickbtn(View view){
        Log.i("This","This is a message");
        Toast.makeText(context, "Button Clicked", Toast.LENGTH_SHORT).show();
    }
}

XML 文件

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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"
    tools:context=".MainActivity">

    <TextView
        android:id="@+id/topText"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="60dp"
        android:includeFontPadding="false"
        android:paddingTop="10dip"
        android:paddingBottom="10dip"
        android:text="Welcome to Shivam Travels"
        android:textAppearance="@style/TextAppearance.AppCompat.Body1"
        android:textSize="24sp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.504"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <EditText
        android:id="@+id/editText"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="32dp"
        android:ems="10"
        android:hint="Enter your username"
        android:inputType="textPersonName"
        app:layout_constraintStart_toStartOf="@+id/topText"
        app:layout_constraintTop_toBottomOf="@+id/topText" />

    <EditText
        android:id="@+id/editText2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="32dp"
        android:ems="10"
        android:hint="Enter your password"
        android:inputType="textPassword"
        app:layout_constraintStart_toStartOf="@+id/editText"
        app:layout_constraintTop_toBottomOf="@+id/editText" />

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="28dp"
        android:onClick="clickbtn"
        android:text="Sign In"
        app:layout_constraintStart_toStartOf="@+id/checkBox"
        app:layout_constraintTop_toBottomOf="@+id/checkBox" />

    <CheckBox
        android:id="@+id/checkBox"
        android:layout_width="176dp"
        android:layout_height="65dp"
        android:layout_marginTop="32dp"
        android:text="Remember me!"
        app:layout_constraintStart_toStartOf="@+id/editText2"
        app:layout_constraintTop_toBottomOf="@+id/editText2" />
</androidx.constraintlayout.widget.ConstraintLayout>

欲了解更多详情:solution

希望这对您现在有帮助。