java - 如何在Java Android Studio中多次运行代码

Question

我是制作 Android 应用程序的新手，我不知道如何多次运行一段代码。这是我的代码:

package com.example.test;

import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageButton;
import android.widget.TextView;
import java.util.Random;
import android.widget.AbsoluteLayout;
import android.util.*;
import java.util.concurrent.TimeUnit;


public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    int score = 0;
    TextView scoreText;
    ImageButton mole;
    Random random = new Random();

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

        scoreText = findViewById(R.id.scoreCount);
        mole = findViewById(R.id.mole);
        //I want to run this multiple times
        TimeUnit.MILLISECONDS.sleep(random.nextInt(500));
        AbsoluteLayout.LayoutParams absParams =
                (AbsoluteLayout.LayoutParams) mole.getLayoutParams();

        DisplayMetrics displaymetrics = new DisplayMetrics();
        getWindowManager().getDefaultDisplay().getMetrics(displaymetrics);
        int width = displaymetrics.widthPixels;
        int height = displaymetrics.heightPixels;


        Random r = new Random();

        absParams.x = r.nextInt(width);
        absParams.y = r.nextInt(height);
        mole.setLayoutParams(absParams);
    }

    @Override
    public void onClick(View v) {

    }
}

我正在尝试制作一个鼹鼠游戏，其中鼹鼠随机穿过屏幕，你必须点击它才能赚取积分，但问题是，我不知道如何运行

TimeUnit.MILLISECONDS.sleep(random.nextInt(500));
        AbsoluteLayout.LayoutParams absParams =
                (AbsoluteLayout.LayoutParams) mole.getLayoutParams();

        DisplayMetrics displaymetrics = new DisplayMetrics();
        getWindowManager().getDefaultDisplay().getMetrics(displaymetrics);
        int width = displaymetrics.widthPixels;
        int height = displaymetrics.heightPixels;


        Random r = new Random();

        absParams.x = r.nextInt(width);
        absParams.y = r.nextInt(height);
        mole.setLayoutParams(absParams);

一次又一次。我尝试过这样做

Thread test = new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    //I want to run this multiple times
                    TimeUnit.MILLISECONDS.sleep(500);
                    AbsoluteLayout.LayoutParams absParams =
                            (AbsoluteLayout.LayoutParams) mole.getLayoutParams();

                    DisplayMetrics displaymetrics = new DisplayMetrics();
                    getWindowManager().getDefaultDisplay().getMetrics(displaymetrics);
                    int width = displaymetrics.widthPixels;
                    int height = displaymetrics.heightPixels;


                    Random r = new Random();

                    absParams.x = r.nextInt(width);
                    absParams.y = r.nextInt(height);
                    mole.setLayoutParams(absParams);
                }catch(InterruptedException e){
                    Log.i("Error", "Thread");
                }
            }
        });
        test.start();

但它不断返回以下错误:

com.example.test E/AndroidRuntime: FATAL EXCEPTION: Thread-1057
    Process: com.example.test, PID: 25335
    android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
        at android.view.ViewRootImpl.checkThread(ViewRootImpl.java:7266)
        at android.view.ViewRootImpl.requestLayout(ViewRootImpl.java:1065)
        at android.view.View.requestLayout(View.java:19098)
        at android.view.View.requestLayout(View.java:19098)
        at android.view.View.requestLayout(View.java:19098)
        at android.view.View.requestLayout(View.java:19098)
        at android.view.View.requestLayout(View.java:19098)
        at android.view.View.requestLayout(View.java:19098)
        at android.view.View.requestLayout(View.java:19098)
        at android.view.View.setLayoutParams(View.java:12590)
        at com.example.test.MainActivity$1.run(MainActivity.java:48)
        at java.lang.Thread.run(Thread.java:818)

Answer 1

您可以使用 RxJava 正如 @Mohammad Reza Khahani 提到的那样，这会让生活更轻松，但如果您不想使用它，您有两个选项来运行您的线程并更改 UI。

第一个是创建 Handler 并在线程内部使用它来运行与 UI 相关的代码:

    Handler handler = new Handler(); // create new instance in ui thread eg: @onCreate or @onResume

    handler.post(new Runnable() {
        @Override
        public void run() {
            //UI changes
        }
    });

或者您可以在后台线程内使用 Activity 的 YourActivity.this.runOnUiThread 方法来运行 UI 相关代码。

    runOnUiThread(new Runnable() {
        @Override
        public void run() {
            //UI changes
        }
    });