Question

我想动态更改按钮颜色。

在编写，测试和研究之后，我发现显示线程应该与代码不同，所以我使用了处理程序。

我试图将按钮的颜色从默认更改为黑色一段时间，然后将其恢复为默认颜色，但它没有发生，它只显示一个默认按钮。

以下是我的代码

import android.content.Intent;
import android.graphics.Color;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

import java.io.IOException;
import java.util.Random;
import android.os.Handler ;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
Button b1;
    Random r = new Random();
    int random_selection;
    int i;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        b1 = (Button) findViewById(R.id.button);

        b1.setOnClickListener(this);



 main();

}
public void main() {
    // Thread t1 = new Thread(new MainActivity());
    // this wi run() function

    Handler handler1 = new Handler();



        handler1.postDelayed(new Runnable() {


            @Override
            public void run() {
                int count = 0;
                try {
                    System.out.println("inside run");
                    for (i=0;i<4 ;i++ )

                      //  android.widget.Toast.makeText(getBaseContext(), count,android.widget.Toast.LENGTH_SHORT).show();
                        Handler handler2 = new Handler();
                        int x = randomgen();
                          //  android.widget.Toast.makeText(getBaseContext(), x,android.widget.Toast.LENGTH_SHORT).show();
                        if (x == 1) {
                            b1.setBackgroundColor(Color.BLACK);
                            handler2.postDelayed(new Runnable() {

                                @Override
                                public void run() {
                                    b1.setBackgroundResource(android.R.drawable.btn_default);
                                }
                            }, 10000);


                        } else if (x == 2) {
                            b2.setBackgroundColor(Color.BLACK);
                            handler2.postDelayed(new Runnable() {

                                @Override
                                public void run() {
                                    b2.setBackgroundResource(android.R.drawable.btn_default);
                                }
                            }, 2000);


                        } else if (x == 3) {
                            b3.setBackgroundColor(Color.BLACK);
                            handler2.postDelayed(new Runnable() {

                                @Override
                                public void run() {
                                    b3.setBackgroundResource(android.R.drawable.btn_default);
                                }
                            }, 2000);


                        } else if (x == 4) {
                            b4.setBackgroundColor(Color.BLACK);
                            handler2.postDelayed(new Runnable() {

                                @Override
                                public void run() {
                                    b4.setBackgroundResource(android.R.drawable.btn_default);
                                }
                            }, 2000);


                        }


                    }
                }catch (Exception e) {
                    System.out.println("inside catch");
                    e.printStackTrace();
                }

            }
        }, 1000 );


}

public int randomgen() {
    random_selection = r.nextInt(4) + 1;
    return random_selection;
}

Answer 1

原因是你的b1.setBackgroundResource(android.R.drawable.btn_default);

在延迟处理程序之外，

将您的功能main更改为：

public void main() {

    int count = 0;
    Handler handler1 = new Handler();

    handler1.postDelayed(new Runnable() {
        Handler handler2 = new Handler();

        @Override
        public void run() {
            try {
                System.out.println("inside run");


                //     android.widget.Toast.makeText(getBaseContext(), x,android.widget.Toast.LENGTH_SHORT).show();

                b1.setBackgroundColor(Color.BLACK);
                handler2.postDelayed(new Runnable() {

                    @Override
                    public void run() {
                        b1.setBackgroundResource(android.R.drawable.btn_default);
                    }
                }, 2000);


            } catch (Exception e) {
                System.out.println("inside catch");
                e.printStackTrace();
            }

        }
    }, 1000);

}

Answer 2

改为使用线程：

b1.setBackgroundColor(Color.BLACK);
new Thread(new Runnable() {
    @Override
    public void run() {
        try { System.sleep(2000) } catch(Exception e) {}
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                b1.setBackgroundResource(android.R.drawable.btn_default);
            }
        });
    }
}).start();

如何动态更改android中的按钮颜色？

2 个答案: