模拟器我的应用不能打开

Question

怎么解决android studio模拟器我的应用不能打开

package com.example.myapplication;

import android.graphics.Color;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

import androidx.appcompat.app.AppCompatActivity;


public class ButtonEnableActivity extends AppCompatActivity implements View.OnClickListener {

     TextView btn_test;

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

        Button btn_enable = findViewById(R.id.btn_enable);
        Button btn_disable=findViewById(R.id.btn_disable);
        //Button btn_test =findViewById(R.id.btn_test);
        TextView tv_result=findViewById(R.id.tv_result);

        //btn_test = findViewById(R.id.tv_result);

        btn_enable.setOnClickListener(this);
        btn_disable.setOnClickListener(this);
        btn_test.setOnClickListener(this);

    }
    @Override
    public void onClick(View v){
        switch (v.getId()){
            case R.id.btn_enable:
                btn_test.setEnabled(true);
                btn_test.setTextColor(Color.BLACK);
                break;
            case R.id.btn_disable:
                btn_test.setEnabled(true);
                btn_test.setTextColor(Color.GRAY);
                break;
        }

    }


}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
<LinearLayout
  android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal">
    <Button
        android:id="@+id/btn_enable"
        android:layout_width="0dp"
        android:layout_weight="1"
        android:layout_height="wrap_content"
        android:textColor="#000000"
        android:textSize="17sp"
        android:text="启动测试按钮"/>
    <Button
        android:id="@+id/btn_disable"
        android:layout_width="0dp"
        android:layout_weight="1"
        android:layout_height="wrap_content"
        android:textColor="#000000"
        android:textSize="17sp"
        android:text="禁用测试按钮"/>
</LinearLayout>
    <Button
        android:id="@+id/btn_test"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textColor="#888888"
        android:textSize="17sp"
        android:text="测试按钮"
        android:enabled="false"/>
    <TextView
        android:id="@+id/tv_result"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textColor="#000000"
        android:textSize="17sp"
        android:text="这里查看测试结果"/>
</LinearLayout>

# Project-wide Gradle settings.
# IDE (e.g. Android Studio) users:
# Gradle settings configured through the IDE *will override*
# any settings specified in this file.
# For more details on how to configure your build environment visit
# http://www.gradle.org/docs/current/userguide/build_environment.html
# Specifies the JVM arguments used for the daemon process.
# The setting is particularly useful for tweaking memory settings.
org.gradle.jvmargs=-Xmx2048m -Dfile.encoding=UTF-8
# When configured, Gradle will run in incubating parallel mode.
# This option should only be used with decoupled projects. For more details, visit
# https://developer.android.com/r/tools/gradle-multi-project-decoupled-projects
# org.gradle.parallel=true
# AndroidX package structure to make it clearer which packages are bundled with the
# Android operating system, and which are packaged with your app's APK
# https://developer.android.com/topic/libraries/support-library/androidx-rn
android.useAndroidX=true
# Enables namespacing of each library's R class so that its R class includes only the
# resources declared in the library itself and none from the library's dependencies,
# thereby reducing the size of the R class for that library
android.nonTransitiveRClass=true
android.nonFinalResIds=false

Answer 1

奶茶精Gaaaa 晚上好🌙🌙🌙
本答案参考ChatGPT-3.5

在你提供的代码中，你在onCreate方法中尝试获取一个id为R.id.btn_test的TextView，但是在布局文件中，并没有定义这个id为btn_test的TextView。因此，当你在onCreate方法中尝试调用btn_test的setOnClickListener方法时，会抛出NullPointerException异常，导致应用无法打开。

为了解决这个问题，你需要按照以下步骤进行修改：

1. 在布局文件中添加一个id为btn_test的TextView，以便在Java代码中找到它。你可以在LinearLayout中添加一个TextView，并给它一个id。

   <TextView
        android:id="@+id/btn_test"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textColor="#888888"
        android:textSize="17sp"
        android:text="测试按钮"
        android:enabled="false" />
   

2. 在Java代码中找到btn_test，并给它设置点击事件。

   btn_test = findViewById(R.id.btn_test);
   btn_test.setOnClickListener(this);
   

这样修改后的代码应该是这样的:

public class ButtonEnableActivity extends AppCompatActivity implements View.OnClickListener {

    TextView btn_test;

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

        Button btn_enable = findViewById(R.id.btn_enable);
        Button btn_disable = findViewById(R.id.btn_disable);
        btn_test = findViewById(R.id.btn_test);
        TextView tv_result = findViewById(R.id.tv_result);

        btn_enable.setOnClickListener(this);
        btn_disable.setOnClickListener(this);
        btn_test.setOnClickListener(this);

    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.btn_enable:
                btn_test.setEnabled(true);
                btn_test.setTextColor(Color.BLACK);
                break;
            case R.id.btn_disable:
                btn_test.setEnabled(true);
                btn_test.setTextColor(Color.GRAY);
                break;
        }

    }

}

希望这可以帮助解决你的问题。如果还有其他问题，请随时提问。